SFU Department of Biological Sciences

Publications of Tony Williams

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207. King, MD; Elliott, JE; Williams, TD. (2021) Effects of petroleum exposure on birds: A review. Sci. Total Environ. 755 Effects of petroleum exposure on birds: A review Oil; Spill; Feathers; Toxicity; Avian; Unconventional oil Birds are vulnerable to petroleum pollution, and exposure has a range of negative effects resulting from plumage fouling, systemic toxicity, and embryotoxicity. Recent research has not been synthesized since Leighton's 1993 review despite the continued discharge of conventional petroleum, including high-volume oil spills and chronic oil pollution, as well as the emergence of understudied unconventional crude oil types. To address this, we reviewed the individual-level effects of crude oil and refined fuel exposure in avifauna with peer-reviewed articles published 1993-2020 to provide a critical synthesis of the state of the science. We also sought to answer how unconventional crude petroleum effects compare with conventional crude oil. Relevant knowledge gaps and research challenges were identified. The resulting review examines avian exposure to petroleum and synthesizes advances regarding the physical effects of oil hydrocarbons on feather structure and function, as well the toxic effects of inhaled or ingested oil, embryotoxicity, and how exposure affects broader scale endpoints related to behavior, reproduction, and survival. Another outcome of the review was the knowledge gaps and challenges identified. The first finding was a paucity of oil ingestion rate estimates in birds. Characterizing environmentally realistic exposure and ingestion rates is a higher research priority than additional conventional oral dosing experiments. Second, there is an absence of toxicity data for unconventional crude petroleum. Although the effects of air and water contamination in the Canadian oil sands region have received attention, toxicity data for direct exposure to unrefined bitumen produced there in high volumes and other such unconventional oil types are needed. Third, we encountered barriers to the interpretation, replication, broad relevance, and comparability of studies. We therefore propose best practices and promising technological advancements for researchers. This review consolidates our understanding of petroleum's effects on birds and points a way forward for researchers and resource managers. Crown Copyright (C) 2020 Published by Elsevier B.V. DOI

206. Criscuolo, F; Torres, R; Zahn, S; Williams, TD. (2020) Telomere dynamics from hatching to sexual maturity and maternal effects in the 'multivariate egg'. J. Exp. Biol. 223 Telomere dynamics from hatching to sexual maturity and maternal effects in the 'multivariate egg' Maternal effects; Egg; Growth; Maternal antibodies; Testosterone; Telomere; Bird Avian eggs contain a large number of molecules deposited by the mother that provide the embryo with energy but also potentially influence its development via the effects of maternally derived hormones and antibodies: the avian egg is thus 'multivariate'. Multivariate effects on offspring phenotype were evaluated in a study on captive zebra finches, by simultaneously manipulating maternally derived antibodies (MAb) by lipopolysaccharide (LPS) treatment of mothers and injection of testosterone into the egg yolk. LPS treatment had a positive effect on body mass growth at 30 days after hatching and immune response at sexual maturity, while egg testosterone treatment positively influenced immune response at fledging and courtship behaviour in sexually mature male offspring. Maternal effects are known to modulate offspring telomere length (TL). However, the multivariate effects of egg-derived maternal components on offspring telomere dynamics from hatching to sexual maturity are undefined. Here, we tested: (1) the effects of LPS and testosterone treatments on TL from hatching to sexual maturity (day 82); (2) how LPS treatment modulated TL over reproduction in adult females; and (3) the relationship between maternal and offspring TL. We predicted that TL would be shorter in LPS fledglings (as a cost of faster growth) and that TL would be longer in sexually mature adults after yolk testosterone treatment (as a proxy of individual quality). In adult females, there was an overall negative relationship between laying and rearing investments and TL, this relationship was weaker in LPS-treated females. In chicks, there was an overall negative effect of LPS treatment on TL measured at fledging and sexual maturity (day 25-82). In addition, at fledging, there was a SexxLPSxTestosterone interaction, suggesting the existence of antagonistic effects of our treatments. Our data partially support the hypothesis that telomeres are proxies of individual quality and that individual differences in TL are established very early in life. DOI

205. Currier, HA; Fremlin, KM; Elliott, JE; Drouillard, KG; Williams, TD. (2020) Bioaccumulation and biomagnification of PBDEs in a terrestrial food chain at an urban landfill. Chemosphere 238 DOI

204. Injaian, AS; Francis, CD; Ouyang, JQ; Dominoni, DM; Donald, JW; Fuxjager, MJ; Goymann, W; Hau, M; Husak, JF; Johnson, MA; Kircher, BK; Knapp, R; Martin, LB; Miller, ET; Schoenle, L; Williams, T; Vitousek, AN. (2020) Baseline and stress-induced corticosterone levels across birds and reptiles do not reflect urbanization levels. Conserv. Physiol. 8 Baseline and stress-induced corticosterone levels across birds and reptiles do not reflect urbanization levels anthropogenic noise; artificial light at night; glucocorticoid; human footprint; population density; stress Rates of human-induced environmental change continue increasing with human population size, potentially altering animal physiology and negatively affecting wildlife. Researchers often use glucocorticoid concentrations (hormones that can be associated with stressors) to gauge the impact of anthropogenic factors (e.g. urbanization, noise and light pollution). Yet, no general relationships between human-induced environmental change and glucocorticoids have emerged. Given the number of recent studies reporting baseline and stress-induced corticosterone (the primary glucocorticoid in birds and reptiles) concentrations worldwide, it is now possible to conduct large-scale comparative analyses to test for general associations between disturbance and baseline and stress-induced corticosterone across species. Additionally, we can control for factors that may influence context, such as life history stage, environmental conditions and urban adaptability of a species. Here, we take a phylogenetically informed approach and use data from HormoneBase to test if baseline and stress-induced corticosterone are valid indicators of exposure to human footprint index, human population density, anthropogenic noise and artificial light at night in birds and reptiles. Our results showa negative relationship between anthropogenic noise and baseline corticosterone for birds characterized as urban avoiders. While our results potentially indicate that urban avoiders are more sensitive to noise than other species, overall our study suggests that the relationship between human-induced environmental change and corticosterone varies across species and contexts; we found no general relationship between human impacts and baseline and stress-induced corticosterone in birds, nor baseline corticosterone in reptiles. Therefore, it should not be assumed that high or low levels of exposure to human-induced environmental change are associated with high or low corticosterone levels, respectively, or that closely related species, or even individuals, will respond similarly. Moving forward, measuring alternative physiological traits alongside reproductive success, health and survival may provide context to better understand the potential negative effects of human-induced environmental change. DOI

203. Jubinville, I; Williams, TD; Trathan, PN; Crossin, GT. (2020) Trade-off between aerobic performance and egg production in migratory macaroni penguins. Comp. Biochem. Physiol. A-Mol. Integr. Physiol. 247 Trade-off between aerobic performance and egg production in migratory macaroni penguins Migration; Hematocrit; Reticulocyte index; Vitellogenesis When successive stages of an organism's life-history overlap, conflicts and trade-offs can emerge due to competition among physiological pathways. For example, long periods of sustained locomotion in migrating birds are supported by the androgenic up-regulation of aerobic factors, such as new red blood cell production and hematocrit. However, towards the end of migration, many female birds begin up-regulating 17 beta-estradiol (E-2) to support vitellogenesis and egg production, but E-2 secretion is known to have suppressive effects on red blood cell production (anti-erythropoiesis). We explored potential trade-offs between factors related to aerobic performance (hematocrit, reticulocyte index) and the expression of factors related to E-2-mediated vitellogenesis (i.e. yolk precursor production) in female macaroni penguins (Eudyptes chrysolophus), a species in which the physiologies controlling egg production and migratory activity run simultaneously (e.g. females experience a migratory conflict). We collected blood samples from penguins immediately upon their return to the colony, prior to egg laying. Hematocrit was elevated when the penguins returned to the colony (50.05% +/- 3.40 SD), which is similar to pre-laying values observed in other migratory bird species. Furthermore, mean reticulocyte levels were elevated (34.87% +/- 2.34), which is the highest level yet recorded in birds. Similarly, both plasma vitellogenin and yolk-targeted very low density lipoprotein levels were upregulated (2.30 +/- 0.06 mu g Zn ml(-1), and 9.70 +/- 0.19 mmol l(-1), respectively), indicating that penguins were reproductively active and producing eggs during migration and upon arrival on land. As predicted, a negative relationship between hematocrit and plasma vitellogenin was found, but we found no evidence to suggest that birds were experiencing reproductive anemia. Alternatively, we attribute the negative relationship to a hemodilution effect of yolk precursor secretion into circulation. It appears that female macaroni penguins are able to preserve hematocrit levels and new red blood cell production when migratory activity overlaps with reproductive processes. DOI

202. Maury, C; Serota, MW; Williams, TD. (2020) Plasticity in diurnal activity and temporal phenotype during parental care in European starlings, Sturnus vulgaris. Anim. Behav. 159: 37-45 Plasticity in diurnal activity and temporal phenotype during parental care in European starlings, Sturnus vulgaris chronotype; daily activity; life history; parental care; plasticity; telemetry We used an automated radiotelemetry system to determine diurnal patterns of activity and temporal phenotype (onset and cessation of activity) in female European starlings during breeding. Parental care is thought to be the most 'costly' part of reproduction, with high rates of intense activity due to foraging and provisioning for chicks, so we predicted that variation in timing of activity should be closely related to breeding success. Diurnal variation in activity varied systematically with breeding stage in a way consistent with specific demands of each phase of parental care: incubating females were more active late in the day (1600-1800 hours), while chick-rearing females were more active early in the morning (0700-1100 hours). There was marked individual variation in timing of onset, and to a lesser extent cessation, of activity, e.g. chick-rearing females first became active 7-127 min after morning civil twilight, with low to moderate repeatability within and among breeding stages (individual explained 2-62% of total variation). On average, females were active later, and ceased being active earlier, during chick rearing compared with incubation. Chick-rearing birds had a longer active day, but only by 2.3% (36% of the seasonal increase in total available daylength). Thus, chick-rearing females were relatively less active ('lazier'), which is consistent with the idea that parents work more efficiently rather than simply working harder. We found little evidence that chick-rearing activity was associated with variation in measures of current reproduction (provisioning rate, number and quality of chicks), future fecundity (initiating a second brood, cumulative 2-year productivity) or survival (local return rate). Our study demonstrates that time-keeping mechanisms show plasticity in response to reproductive state and can be modulated by 'biotic' (e.g. prey availability) or 'social' time (demands of parental care). (C) 2019 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. DOI

201. Criscuolo, F; Cornell, A; Zahn, S; Williams, TD. (2019) Oxidative status and telomere length are related to somatic and physiological maturation in chicks of European starlings (Stumus vulgaris). J. Exp. Biol. 222 DOI

200. Eng, ML; Karouna-Renier, NK; Henry, PFP; Letcher, RJ; Schultz, SL; Bean, TG; Peters, LE; Palace, VP; Williams, TD; Elliott, JE; Fernie, KJ. (2019) In ovo exposure to brominated flame retardants Part II: Assessment of effects of TBBPA-BDBPE and BTBPE on hatching success, morphometric and physiological endpoints in American kestrels. Ecotox. Environ. Safe. 179: 151-159 In ovo exposure to brominated flame retardants Part II: Assessment of effects of TBBPA-BDBPE and BTBPE on hatching success, morphometric and physiological endpoints in American kestrels Brominated flame retardants; Emerging flame retardants; American kestrels Falco sparverius; Avian toxicity; Developmental toxicity; Deiodinase enzymes Tetrabromobisphenol A bis(2,3-dibromopropyl ether) (TBBPA-BDBPE) and 1,2-bis(2,4,6-tribromophenoxy) ethane (BTPBE) are both brominated flame retardants (BFRs) that have been detected in birds; however, their potential biological effects are largely unknown. We assessed the effects of embryonic exposure to TBBPA-BDBPE and BTBPE in a model avian predator, the American kestrel (Falco sparverius). Fertile eggs from a captive population of kestrels were injected on embryonic day 5 (ED5) with a vehicle control or one of three doses within the range of concentrations that have been detected in biota (nominal concentrations of 0, 10, 50 or 100 ng/g egg; measured concentrations 0, 3.0, 13.7 or 33.5 ng TBBPA-BDBPE/g egg and 0, 5.3, 26.8 or 58.1 ng BTBPE/g egg). Eggs were artificially incubated until hatching (ED28), at which point blood and tissues were collected to measure morphological and physiological endpoints, including organ somatic indices, circulating and glandular thyroid hormone concentrations, thyroid gland histology, hepatic deiodinase activity, and markers of oxidative stress. Neither compound had any effects on embryo survival through 90% of the incubation period or on hatching success, body mass, organ size, or oxidative stress of hatchlings. There was evidence of sex-specific effects in the thyroid system responses to the BTBPE exposures, with type 2 deiodinase (D2) activity decreasing at higher doses in female, but not in male hatchlings, suggesting that females may be more sensitive to BTBPE. However, there were no effects of TBBPA-BDBPE on the thyroid system in kestrels. For the BTPBE study, a subset of high-dose eggs was collected throughout the incubation period to measure changes in BTBPE concentrations. There was no decrease in BTBPE over the incubation period, suggesting that BTBPE is slowly metabolized by kestrel embryos throughout their similar to 28-d development. These two compounds, therefore, do not appear to be particularly toxic to embryos of the American kestrel. DOI

199. Eng, ML; Williams, TD; Fernie, KJ; Renier, NKK; Henry, PFP; Letcher, RJ; Elliott, JE. (2019) In ovo exposure to brominated flame retardants Part I: Assessment of effects of TBBPA-BDBPE on survival, morphometric and physiological endpoints in zebra finches. Ecotox. Environ. Safe. 179: 104-110 In ovo exposure to brominated flame retardants Part I: Assessment of effects of TBBPA-BDBPE on survival, morphometric and physiological endpoints in zebra finches Brominated flame retardants; Emerging flame retardants; Avian; Zebra finch; Developmental toxicity; Tetrabromobisphenol A derivative Tetrabromobisphenol A bis(2,3-dibromopropyl) ether (TBBPA-BDBPE) is an additive flame retardant used in polyolefins and polymers. It has been detected in biota, including in avian eggs, yet little is known of its effects. We assessed the pattern of TBBPA-BDBPE concentrations in songbird eggs over the incubation period, and the effects of embryonic exposure to TBBPA-BDBPE in a model songbird species, the zebra finch (Taeniopygia guttata). To assess concentrations during embryo development, eggs were injected on the day they were laid with the vehicle control (safflower oil) or 100 ng TBBPA-BDBPE/g egg, and whole egg contents were collected throughout embryonic development on day 0 (unincubated), 5, 10 and 13. To evaluate effects of embryonic exposure to TBBPA-BDBPE, eggs were injected at Hamburger-Hamilton stage 18 (similar to 80 h after initiation of incubation) with safflower oil only, 10, 50 or 100 ng TBBPA-BDBPE/g egg (albumin injection volume 1 mu l/g). Eggs were monitored for hatching success, and nestlings were monitored for growth and survival. At 15 days post-hatch, tissues were collected to assess physiological effects. TBBPA-BDBPE was incorporated into the egg as the embryo developed, and concentrations started declining in late incubation, suggesting biotransformation by the embryo. There were no effects on hatching success, nestling survival, growth, organ somatic indices, or thyroid hormone homeostasis; however, there was evidence that body condition declined in a dose-dependent manner towards the end of the rapid nestling growth phase. This decreased body condition could be a delayed effect of early developmental exposure, or it may be the result of increased exposure to biotransformation products of TBBPA-BDBPE produced over the nestling period, which are predicted to be more bioaccumulative and toxic than the parent compound. DOI

198. Laine, VN; Verhagen, I; Mateman, AC; Pijl, A; Williams, TD; Gienapp, P; van Oers, K; Visser, ME. (2019) Exploration of tissue-specific gene expression patterns underlying timing of breeding in contrasting temperature environments in a song bird. BMC Genomics 20 Exploration of tissue-specific gene expression patterns underlying timing of breeding in contrasting temperature environments in a song bird Transcriptomics; Seasonal timing; Aves; Selection line Background Seasonal timing of breeding is a life history trait with major fitness consequences but the genetic basis of the physiological mechanism underlying it, and how gene expression is affected by date and temperature, is not well known. In order to study this, we measured patterns of gene expression over different time points in three different tissues of the hypothalamic-pituitary-gonadal-liver axis, and investigated specifically how temperature affects this axis during breeding. We studied female great tits (Parus major) from lines artificially selected for early and late timing of breeding that were housed in two contrasting temperature environments in climate-controlled aviaries. We collected hypothalamus, liver and ovary samples at three different time points (before and after onset of egg-laying). For each tissue, we sequenced whole transcriptomes of 12 pools (n = 3 females) to analyse gene expression. Results Birds from the selection lines differed in expression especially for one gene with clear reproductive functions, zona pellucida glycoprotein 4 (ZP4), which has also been shown to be under selection in these lines. Genes were differentially expressed at different time points in all tissues and most of the differentially expressed genes between the two temperature treatments were found in the liver. We identified a set of hub genes from all the tissues which showed high association to hormonal functions, suggesting that they have a core function in timing of breeding. We also found ample differentially expressed genes with largely unknown functions in birds. Conclusions We found differentially expressed genes associated with selection line and temperature treatment. Interestingly, the latter mainly in the liver suggesting that temperature effects on egg-laying date may happen down-stream in the physiological pathway. These findings, as well as our datasets, will further the knowledge of the mechanisms of tissue-specific avian seasonality in the future. DOI

197. Serota, MW; Williams, TD. (2019) Adjustment of total activity as a response to handicapping European starlings during parental care. Anim. Behav. 148 Adjustment of total activity as a response to handicapping European starlings during parental care activity; automated telemetry; costs of reproduction; handicapping; parental care Parental care is widely assumed to be costly, and life-history theory predicts that individuals that invest more in parental care should benefit in terms of number of offspring produced but that increased parental care might come at a cost in terms of decreased future fecundity and/or survival. However, the notion that parents that work 'harder', commonly measured by the rate at which parents visit the nestbox to provision their chicks, produce more, fitter chicks is surprisingly poorly supported. One potential reason for this apparent lack of relationship between measured workload during parental care and breeding productivity is that nest visit rate does not provide a good measure of foraging effort. Here, we used an automated radiotelemetry system to measure activity of individual female European starlings, Sturnus vulgaris, during breeding, combined with a handicapping experiment (combination of radiotransmitters and wing clipping) and measures of foraging metrics, current breeding productivity, future fecundity and return rate. Handicapping decreased current breeding success due to higher abandonment and nest failure, but among successful birds (fledging >= 1 chick) there was no effect of handicapping on brood size at fledging for the current breeding attempt. Handicapping decreased future fecundity, the probability of initiating a second brood, and return rate, but there was no evidence for additive costs of reproduction in wing-clipped females. Handicapping had no effect on provisioning rate but automated tracking data showed that, during chick rearing, wing-clipped females had 22% lower activity compared to females with radios only. Our data provide an explanation for the often contradictory effects of handicapping reported on reproductive effort and costs of reproduction: individuals can use behavioural flexibility - decreasing overall activity while maintaining provisioning rate - along with changes in mass and nestling diet to mitigate putative effects of increased workload imposed by handicapping. (C) 2018 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. DOI

196. Torres, R; Chin, E; Rampton, R; Williams, TD. (2019) Are there synergistic or antagonistic effects of multiple maternally derived egg components on offspring phenotype? J. Exp. Biol. 222 DOI

195. Verhagen, I; Laine, VN; Mateman, AC; Pijl, A; de Wit, R; van Lith, B; Kamphuis, W; Viitaniemi, HM; Williams, TD; Caro, SP; Meddle, SL; Gienapp, P; van Oers, K; Visser, ME. (2019) Fine-tuning of seasonal timing of breeding is regulated downstream in the underlying neuro-endocrine system in a small songbird. J. Exp. Biol. 222 DOI

194. Vitousek, MN; Johnson, MA; Downs, CJ; Miller, ET; Martin, LB; Francis, CD; Donald, JW; Fuxjager, MJ; Goymann, W; Hau, M; Husak, JF; Kircher, BK; Knapp, R; Schoenle, LA; Williams, TD. (2019) Macroevolutionary Patterning in Glucocorticoids Suggests Different Selective Pressures Shape Baseline and Stress-Induced Levels. Am. Nat. 193: 866-880 DOI

193. Williams, TD; Cornell, A; Gillespie, C; Hura, A; Serota, M. (2019) Effects of an introduced, novel prey on diet and reproduction in the diet-specialist European Starling (Sturnus vulgaris). Can. J. Zool. 97 DOI

192. Yap, KN; Tsai, OHI; Williams, TD. (2019) Haematological traits co-vary with migratory status, altitude and energy expenditure: a phylogenetic, comparative analysis. Sci Rep 9 DOI

191. Casagrande, S; Garamszegi, LZ; Goymann, W; Donald, J; Francis, CD; Fuxjager, MJ; Husak, JF; Johnson, MA; Kircher, B; Knapp, R; Martin, LB; Miller, ET; Schoenle, LA; Vitousek, MN; Williams, TD; Hau, M. (2018) Do Seasonal Glucocorticoid Changes Depend on Reproductive Investment? A Comparative Approach in Birds. Integr. Comp. Biol. 58 Do Seasonal Glucocorticoid Changes Depend on Reproductive Investment? A Comparative Approach in Birds Animals go through different life history stages such as reproduction, moult, or migration, of which some are more energy-demanding than others. Baseline concentrations of glucocorticoid hormones increase during moderate, predictable challenges and thus are expected to be higher when seasonal energy demands increase, such as during reproduction. By contrast, stress-induced glucocorticoids prioritize a survival mode that includes reproductive inhibition. Thus, many species down-regulate stress-induced glucocorticoid concentrations during the breeding season. Interspecific variation in glucocorticoid levels during reproduction has been successfully mapped onto reproductive investment, with species investing strongly in current reproduction (fast pace of life) showing higher baseline and lower stress-induced glucocorticoid concentrations than species that prioritize future reproduction over current attempts (slow pace of life). Here we test the "glucocorticoid seasonal plasticity hypothesis", in which we propose that interspecific variation in seasonal changes in glucocorticoid concentrations from the non-breeding to the breeding season will be related to the degree of reproductive investment (and thus pace of life). We extracted population means for baseline (for 54 species) and stress-induced glucocorticoids (for 32 species) for the breeding and the non-breeding seasons from the database "HormoneBase", also calculating seasonal glucocorticoid changes. We focused on birds because this group offered the largest sample size. Using phylogenetic comparative methods, we first showed that species differed consistently in both average glucocorticoid concentrations and their changes between the two seasons, while controlling for sex, latitude, and hemisphere. Second, as predicted seasonal changes in baseline glucocorticoids were explained by clutch size (our proxy for reproductive investment), with species laying larger clutches showing a greater increase during the breeding season-especially in passerine species. In contrast, changes in seasonal stress-induced levels were not explained by clutch size, but sample sizes were more limited. Our findings highlight that seasonal changes in baseline glucocorticoids are associated with a species' reproductive investment, representing an overlooked physiological trait that may underlie the pace of life. DOI

190. Eng, ML; Winter, V; Elliott, JE; MacDougall-Shackleton, SA; Williams, TD. (2018) Embryonic Exposure to Environmentally Relevant Concentrations of a Brominated Flame Retardant Reduces the Size of Song-Control Nuclei in a Songbird. Dev. Neurobiol. 78 DOI

189. Fowler, MA; Paquet, M; Legault, V; Cohen, AA; Williams, TD. (2018) Physiological predictors of reproductive performance in the European Starling (Sturnus vulgaris). Front. Zool. 15 Physiological predictors of reproductive performance in the European Starling (Sturnus vulgaris) Dysregulation; European starling; Physiological complexity; Physiological state; Principal components analysis; Reproductive fitness; Statistical distance; Sturnus vulgaris Background: It is widely assumed that variation in fitness components has a physiological basis that might underlie selection on trade-offs, but the mechanisms driving decreased survival and future fecundity remain elusive. Here, we assessed whether physiological variables are related to workload ability or immediate fitness consequences and if they mediate future survival or reproductive success. We used data on 13 physiological variables measured in 93 female European starlings (Sturnus vulgaris) at two breeding stages (incubation, chick-rearing), for first-and second-broods over two years (152 observations). Results: There was little co-variation among the physiological variables, either in incubating or chick-rearing birds, but some systematic physiological differences between the two stages. Chick-rearing birds had lower hematocrit and plasma creatine kinase but higher hemoglobin, triglyceride and uric acid levels. Only plasma corticosterone was repeatable between incubation and chick-rearing. We assessed relationships between incubation or chick-rearing physiology and measures of workload, current productivity, future fecundity or survival in a univariate manner, and found very few significant relationships. Thus, we next explored the utility of multivariate analysis (principal components analysis, Mahalanobis distance) to account for potentially complex physiological integration, but still found no clear associations. Conclusions: This implies either that a) birds maintained physiological variables within a homeostatic range that did not affect their performance, b) there are relatively few links between physiology and performance, or, more likely, c) that the complexity of these relationships exceeds our ability to measure it. Variability in ecological context may complicate the relationship between physiology and behavior. We thus urge caution regarding the over-interpretation of isolated significant findings, based on single traits in single years, in the literature. DOI

188. Francis, CD; Donald, JW; Fuxjager, MJ; Goymann, W; Hau, M; Husak, JF; Johnson, MA; Kircher, BK; Knapp, R; Martin, LB; Miller, ET; Schoenle, LA; Vitousek, MN; Williams, TD; Downs, CJ. (2018) Metabolic Scaling of Stress Hormones in Vertebrates. Integr. Comp. Biol. 58 Metabolic Scaling of Stress Hormones in Vertebrates Glucocorticoids (GCs) are stress hormones that can strongly influence physiology, behavior, and an organism's ability to cope with environmental change. Despite their importance, and the wealth of studies that have sought to understand how and why GC concentrations vary within species, we do not have a clear understanding of how circulating GC levels vary within and across the major vertebrate clades. New research has proposed that much interspecific variation in GC concentrations can be explained by variation in metabolism and body mass. Specifically, GC concentrations should vary proportionally with mass-specific metabolic rates and, given known scaling relationships between body mass and metabolic rate, GC concentrations should scale to the -1/4 power of body mass and to the power of 1 with mass-specific metabolic rate. Here, we use HormoneBase, the newly compiled database that includes plasma GC concentrations from free-living and unmanipulated vertebrates, to evaluate this hypothesis. Specifically, we explored the relationships between body mass or mass-specific metabolic rate and either baseline or stress-induced GC (cortisol or corticosterone) concentrations in tetrapods. Our phylogenetically-informed models suggest that, whereas the relationship between GC concentrations and body mass across tetrapods and among mammals is close to -1/4 power, this relationship does not exist in amphibians, reptiles, and birds. Moreover, with the exception of a positive association between stress-induced GC concentrations and mass-specific metabolic rate in birds, we found little evidence that GC concentrations are linked to metabolic rate, although the number of species sampled was quite limited for amphibians and somewhat so for reptiles and mammals. Nevertheless, these results stand in contrast to the generally accepted association between the two and suggest that our observed positive association between body mass and GC concentrations may not be due to the well-established link between mass and metabolism. Large-scale comparative approaches can come with drawbacks, such as pooling and pairing observations from separate sources. However, these broad analyses provide an important counterbalance to the majority of studies examining variation in GC concentrations at the population or species level, and can be a powerful approach to testing both long-standing and new questions in biology. DOI

187. Garamszegi, LZ; Donald, J; Francis, CD; Fuxjager, MJ; Goymann, W; Hau, M; Husak, JF; Johnson, MA; Kircher, B; Knapp, R; Martin, LB; Miller, ET; Schoenle, LA; Vitousek, MN; Williams, TD. (2018) Species-Specific Means and Within-Species Variance in Glucocorticoid Hormones and Speciation Rates in Birds. Integr. Comp. Biol. 58 DOI

186. Hennin, HL; Dey, CJ; Bety, J; Gilchrist, HG; Legagneux, P; Williams, TD; Love, OP. (2018) Higher rates of prebreeding condition gain positively impacts clutch size: A mechanistic test of the condition-dependent individual optimization model. Funct. Ecol. 32 Higher rates of prebreeding condition gain positively impacts clutch size: A mechanistic test of the condition-dependent individual optimization model clutch size; common eider; condition gain; fattening rate; individual optimization; laying date; path analysis; triglyceride 1. A combination of timing of and body condition (i.e., mass) at arrival on the breeding grounds interact to influence the optimal combination of the timing of reproduction and clutch size in migratory species. This relationship has been formalized by Rowe et al. in a condition-dependent individual optimization model (American Naturalist, 1994, 143, 689-722), which has been empirically tested and validated in avian species with a capital-based breeding strategy. 2. This model makes a key, but currently untested prediction; that variation in the rate of body condition gain will shift the optimal combination of laying date and clutch size. This prediction is essential because it implies that individuals can compensate for the challenges associated with late timing of arrival or poor body condition at arrival on the breeding grounds through adjustment of their life history investment decisions, in an attempt to maximize fitness. 3. Using an 11-year data set in arctic-nesting common eiders (Somateria mollissima), quantification of fattening rates using plasma triglycerides (an energetic metabolite), and a path analysis approach, we test this prediction of this optimization model; controlling for arrival date and body condition, females that fatten more quickly will adjust the optimal combination of lay date and clutch size, in favour of a larger clutch size. 4. As predicted, females fattening at higher rates initiated clutches earlier and produced larger clutch sizes, indicating that fattening rate is an important factor in addition to arrival date and body condition in predicting individual variation in reproductive investment. However, there was no direct effect of fattening rate on clutch size (i.e., birds laying on the same date had similar clutch sizes, independent of their fattening rate). Instead, fattening rate indirectly affected clutch size via earlier lay dates, thus not supporting the original predictions of the optimization model. 5. Our results demonstrate that variation in the rate of condition gain allows individuals to shift flexibly along the seasonal decline in clutch size to presumably optimize the combination of laying date and clutch size. DOI

185. Martin, LB; Vitousek, M; Donald, JW; Flock, T; Fuxjager, MJ; Goymann, W; Hau, M; Husak, J; Johnson, MA; Kircher, B; Knapp, R; Miller, ET; Schoenle, LA; Williams, T; Francis, CD. (2018) IUCN Conservation Status Does Not Predict Glucocorticoid Concentrations in Reptiles and Birds. Integr. Comp. Biol. 58 DOI

184. Morran, SAM; Elliott, JE; Young, JML; Eng, ML; Basu, N; Williams, TD. (2018) Ecologically-relevant exposure to methylmercury during early development does not affect adult phenotype in zebra finches (Taeniopygia guttata). Ecotoxicology 27 DOI

183. Vitousek, MN; Johnson, MA; Donald, JW; Francis, CD; Fuxjager, MJ; Goymann, W; Hau, M; Husak, JF; Kircher, BK; Knapp, R; Martin, LB; Miller, ET; Schoenle, LA; Uehling, JJ; Williams, TD. (2018) Data Descriptor: HormoneBase, a population-level database of steroid hormone levels across vertebrates. Sci. Data 5 DOI

182. Williams, TD. (2018) Physiology, activity and costs of parental care in birds. J. Exp. Biol. 221 DOI

181. Yap, KN; Dick, MF; Guglielmo, CG; Williams, TD. (2018) Effects of experimental manipulation of hematocrit on avian flight performance in high- and low-altitude conditions. J. Exp. Biol. 221 DOI

180. Cornell, A; Gibson, KF; Williams, TD. (2017) Physiological maturity at a critical life-history transition and flight ability at fledging. Functional Ecology 31: 662-670 Physiological maturity at a critical life-history transition and flight ability at fledging developmental maturity; fledging; flight ability; haemoglobin; life-history transition; physiology <ol start="1" class=""> <li>Developmental maturity (e.g. body condition, body mass) at major life-history transitions is known to affect fitness across a wide range of taxa.</li> <li>Fledging (leaving the nest), a major life-history transition in birds, is associated with high post-fledging mortality and is widely assumed to be related to poor initial flight ability of fledglings, which, in turn, might be related to developmental maturity at fledging.</li> <li>We investigated individual variation in developmental maturity of both somatic and physiological traits at this critical life-history transition in different ecological contexts (year, first or second broods) to determine the importance of physiological traits related to oxygen-carrying capacity (haematocrit, haemoglobin) for individual variation in initial flight ability at fledging.</li> <li>Haemoglobin concentration and haematocrit at fledging had much higher variance than somatic traits and were more variable across ecological contexts. Furthermore, fledgling haemoglobin concentration was the least developmentally mature of all traits (on average, only 78% of adult concentration).</li> <li>Fledglings from second broods, which are known to have lower post-fledging survival, were less developmentally mature than fledglings from first broods for all traits (except tarsus), with haematocrit and haemoglobin concentration being the most developmentally immature traits (in first vs. second broods, haematocrit: 47·1% vs. 40·9%; haemoglobin: 13·3 vs. 11·6 g dL<sup>−1</sup>).</li> <li>Models predicting individual variation in two aspects of initial flight ability (total energy gain, take-off angle) were significantly improved when physiological traits (in particular haemoglobin) were incorporated into models based on somatic traits.</li> </ol> DOI

179. Cornell, A; Hou, JJ; Williams, TD. (2017) Experimentally increased prebreeding male social behaviour has no effect on female breeding phenology and performance. Animal Behaviour 126: 243-251 DOI

178. Cornell, A; Williams, TD. (2017) Variation in developmental trajectories of physiological and somatic traits in a common songbird approaching fledging. Journal of Experimental Biology 220: 4060-4067 DOI

177. Crossin, GT; Phillips, RA; Lattin, CR; Romero, LM; Bordeleau, X; Harris, CM; Love, OP; Williams, TD. (2017) Costs of reproduction and carry-over effects in breeding albatrosses. Antarctic Science 29: 155-164 DOI

176. Davis, ML; Elliott, JE; Williams, TD. (2017) The Glaucous-Winged Gull (Larus glaucescens) as an Indicator of Chemical Contaminants in the Canadian Pacific Marine Environment: Evidence from Stable Isotopes. Arch. Environ. Contam. Toxicol. 73: 247-255 DOI

175. Eng, ML; Bishop, CA; Crump, D; Jones, SP; Williams, TD; Drouillard, KG; Elliott, JE. (2017) Catbirds are the New Chickens: High Sensitivity to a Dioxin-like Compound in a Wildlife Species. Environ. Sci. Technol. 51: 5252-5258 DOI

174. Eng, ML; Letcher, RJ; Williams, TD; Elliott, JE. (2017) In ovo tris(2-butoxyethyl) phosphate concentrations significantly decrease in late incubation after a single exposure via injection, with no evidence of effects on hatching success or latent effects on growth or reproduction in zebra finches. Environmental Toxicology and Chemistry 36: 83-88 DOI

173. Fowler, MA; Williams, TD. (2017) A Physiological Signature of the Cost of Reproduction Associated with Parental Care. Am. Nat. 190: 762-773 DOI

172. Gibson, KF; Williams, TD. (2017) Intraclutch egg size variation is independent of ecological context among years in the European Starling Sturnus vulgaris. J. Ornithol. 158: 1099-1110 Intraclutch egg size variation is independent of ecological context among years in the European Starling Sturnus vulgaris Individual variation; Early brood loss; Hatching asynchrony; Offspring quality; Adaptive strategy Female birds can potentially utilise various mechanisms, such as intraclutch egg size variation (ICESV), to modulate offspring quality. If this represents an 'adaptive' strategy allowing females to adjust reproductive effort after laying of the first egg, as information on resources becomes more predictable later in the laying sequence, then we would predict that ICESV would vary with ecological context, e.g. in 'good' versus 'bad' years. Here, in European Starlings (Sturnus vulgaris), we tested specific predictions that (1) females would lay relatively small last laid eggs in 'poor' years (with early laying and below-average breeding productivity); and (2) that ICESV would be lower in good years (late laying, above-average productivity) so that late-hatched chicks would not be disadvantaged. At the individual level we predicted (3) that repeatability of ICESV would be low if females adjusted this in relation to the environment in different years; and (4) that within-individual variation in ICESV should correlate with the number, and timing, of loss of chicks. Mean ICESV averaged -1.9% (measured as last egg mass relative to mean egg mass), typical of other hole-nesting passerines. However, our results did not support any of our hypotheses: (1) although there was annual variation in ICESV, in all years egg mass decreased through the laying sequence; (2) annual variation in ICESV was not consistent with variation in phenology or breeding productivity among years; (3) marked individual variation in ICESV (last laid egg varied from -20 to +10% relative to mean egg mass within clutches) was repeatable, i.e. individual females did not adjust ICESV in subsequent breeding attempts; and (4) variation in the magnitude of ICESV, alone and combined with hatching asynchrony, did not predict early brood loss. Our study suggests that ICESV is a relatively inflexible component of an individual female's phenotype that might contribute to variation in individual quality. DOI

171. Gorman, KB; Talbot, SL; Sonsthagen, SA; Sage, GK; Gravely, MC; Fraser, WR; Williams, TD. (2017) Population genetic structure and gene flow of Adelie penguins (Pygoscelis adeliae) breeding throughout the western Antarctic Peninsula. Antarctic Science 29: 499-510 DOI

170. Griffith, SC; Crino, OL; Andrew, SC; Nomano, FY; Adkins-Regan, E; Alonso-Alvarez, C; Bailey, IE; Bittner, SS; Bolton, PE; Boner, W; Boogert, N; Boucaud, ICA; Briga, M; Buchanan, KL; Caspers, BA; Cichon, M; Clayton, DF; Deregnaucourt, S; Forstmeier, W; Guillette, LM; Hartley, IR; Healy, SD; Hill, DL; Holveck, MJ; Hurley, LL; Ihle, M; Krause, ET; Mainwaring, MC; Marasco, V; Mariette, MM; Martin-Wintle, MS; McCowan, LSC; McMahon, M; Monaghan, P; Nager, RG; Naguib, M; Nord, A; Potvin, DA; Prior, NH; Riebel, K; Romero-Haro, AA; Royle, NJ; Rutkowska, J; Schuett, W; Swaddle, JP; Tobler, M; Trompf, L; Varian-Ramos, CW; Vignal, C; Villain, AS; Williams, TD. (2017) Variation in Reproductive Success Across Captive Populations: Methodological Differences, Potential Biases and Opportunities. Ethology 123: 1-29 DOI

169. Killen, SS; Calsbeek, R; Williams, TD. (2017) The Ecology of Exercise: Mechanisms Underlying Individual Variation in Behavior, Activity, and Performance: An Introduction to Symposium. Integr. Comp. Biol. 57: 185-194 The Ecology of Exercise: Mechanisms Underlying Individual Variation in Behavior, Activity, and Performance: An Introduction to Symposium Wild animals often engage in intense physical activity while performing tasks vital for their survival and reproduction associated with foraging, avoiding predators, fighting, providing parental care, and migrating. In this theme issue we consider how viewing these tasks as "exercise"-analogous to that performed by human athletes-may help provide insight into the mechanisms underlying individual variation in these types of behaviors and the importance of physical activity in an ecological context. In this article and throughout this issue, we focus on four key questions relevant to the study of behavioral ecology that may be addressed by studying wild animal behavior from the perspective of exercise physiology: (1) How hard do individual animals work in response to ecological (or evolutionary) demands?; (2) Do lab-based studies of activity provide good models for understanding activity in free-living animals and individual variation in traits?; (3) Can animals work too hard during "routine" activities?; and (4) Can paradigms of "exercise" and "training" be applied to free-living animals? Attempts to address these issues are currently being facilitated by rapid technological developments associated with physiological measurements and the remote tracking of wild animals, to provide mechanistic insights into the behavior of free-ranging animals at spatial and temporal scales that were previously impossible. We further suggest that viewing the behaviors of non-human animals in terms of the physical exercise performed will allow us to fully take advantage of these technological advances, draw from knowledge and conceptual frameworks already in use by human exercise physiologists, and identify key traits that constrain performance and generate variation in performance among individuals. It is our hope that, by highlighting mechanisms of behavior and performance, the articles in this issue will spur on further synergies between physiologists and ecologists, to take advantage of emerging cross-disciplinary perspectives and technologies. DOI

168. Yap, KN; Kim, OR; Harris, KC; Williams, TD. (2017) Physiological effects of increased foraging effort in a small passerine. Journal of Experimental Biology 220: 4282-4291 Physiological effects of increased foraging effort in a small passerine Exercise physiology; Workload; Oxidative stress; Energetics; Body composition; Taeniopygia guttata Foraging to obtain food, either for self-maintenance or at presumably elevated rates to provide for offspring, is thought to be an energetically demanding activity but one that is essential for fitness (higher reproductive success and survival). Nevertheless, the physiological mechanisms that allow some individuals to support higher foraging performance, and the mechanisms underlying costs of high workload, remain poorly understood. We experimentally manipulated foraging behaviour in zebra finches (Taeniopygia guttata) using the technique described by Koetsier and Verhulst (2011). Birds in the 'high foraging effort' (HF) group had to obtain food either while flying/hovering or by making repeated hops or jumps from the ground up to the feeder, behaviour typical of the extremely energetically expensive foraging mode observed in many free-living small passerines. HF birds made significantly more trips to the feeder per 10 min, whereas control birds spent more time (perched) at the feeder. Despite this marked change in foraging behaviour, we documented few short- or long-term effects of 'training' (3 days and 90 days of 'training', respectively) and some of these effects were sex specific. There were no effects of treatment on basal metabolic rate, haematocrit, haemoglobin or plasma glycerol, triglyceride and glucose levels, and masses of kidney, crop, large intestine, small intestine, gizzard and liver. HF females had higher masses of flight muscle, leg muscle, heart and lung compared with controls. In contrast, HF males had lower heart mass than controls and there were no differences for other organs. When both sexes were pooled, there were no effects of treatment on body composition. Finally, birds in the HF treatment group had higher levels of reactive oxygen metabolites (dROMs) and, consequently, although treatment did not affect total anti-oxidant capacity, birds in the HF treatment group had higher oxidative stress. DOI

167. Yap, KN; Serota, MW; Williams, TD. (2017) The Physiology of Exercise in Free-Living Vertebrates: What Can We Learn from Current Model Systems? Integr. Comp. Biol. 57: 195-206 DOI

166. Yu, MS; Eng, ML; Williams, TD; Guigueno, MF; Elliott, JE. (2017) Assessment of neuroanatomical and behavioural effects of in ovo methylmercury exposure in zebra finches (Taeniopygia guttata). Neurotoxicology 59: 33-39 DOI

165. Cornell, A; Williams, TD. (2016) Individual quality and double-brooding in a highly synchronous songbird population. Auk 133: 251-260 DOI

164. Crossin, GT; Love, OP; Cooke, SJ; Williams, TD. (2016) Glucocorticoid manipulations in free-living animals: considerations of dose delivery, life-history context and reproductive state. Functional Ecology 30: 116-125 Glucocorticoid manipulations in free-living animals: considerations of dose delivery, life-history context and reproductive state baseline levels; corticosterone; cortisol; fitness; glucocorticoids; implants 1. Experimental glucocorticoid (GC) manipulations can be useful for identifying the mechanisms that drive life-history and fitness variation in free-living animals, but predicting the effects of GC treatment can be complicated. Much of the uncertainty stems from the multifaceted role of GCs in organismal metabolism, and their variable influence with respect to life-history stage, ecological context, age, sex and individual variation. 2. Glucocorticoid hormones have been implicated in the regulation of parental care in many vertebrate taxa but in two seemingly contradictory ways, which sets up a potential GC-induced 'reproductive conflict'. Circulating GCs mediate adaptive physiological and behavioural responses to stressful events, and elevated levels can lead to trade offs between reproductive effort and survival (e.g. the current reproduction vs. survival hypothesis). The majority of studies examining the fitness effects of GC manipulations extend from this hypothesis. However, when animals are not stressed (likely most of the time) baseline GCs act as key metabolic regulators of daily energy balance, homoeostasis, osmoregulation and food acquisition, with pleiotropic effects on locomotor activity or foraging behaviour. Slight increases in circulating baseline levels can then have positive effects on reproductive effort (e.g. the 'cort' fitness/adaptation hypotheses), but comparatively few GC manipulation studies have targeted these small, non-stress induced increases. 3. We review studies of GC manipulations and examine the specific hypotheses used to predict the effects of manipulations in wild, breeding vertebrates. We argue that given the dichotomous function of GCs the current 'reproduction vs. survival' paradigm is unnecessarily restrictive and predicts only deleterious GC effects on fitness. Therefore, a broader set of hypotheses should be considered when testing the fitness effects of GC manipulations. 4. When framing experimental manipulation studies, we urge researchers to consider three key points: life-history context (e.g. long vs. short lived, semelparous vs. iteroparous, etc.), ecological context and dose delivery. DOI

163. Fronstin, RB; Christians, JK; Williams, TD. (2016) Experimental reduction of haematocrit affects reproductive performance in European starlings. Functional Ecology 30: 398-409 Experimental reduction of haematocrit affects reproductive performance in European starlings cost of reproduction; haemoglobin; interindividual variation; reproductive anaemia; reproductive success 1. Given the function of haemoglobin and observed increases in haematocrit during periods of increased energetic demands, haematocrit and haemoglobin are assumed to be related to aerobic capacity. Reductions in haematocrit and haemoglobin during reproduction are similar in magnitude to increases associated with aerobically demanding activities, and therefore, we sought to investigate whether these reductions in haematology have consequences for reproductive performance. 2. We analysed associations between natural variation in haematology in free-living European starlings (Sturnus vulgaris) and reproductive performance. To test whether transient reductions in haematology during different stages of reproduction (egg production and late incubation/early chick rearing) affected measures of reproductive performance, we also manipulated haematology using phenylhydrazine (PHZ), which lyses red blood cells. 3. To investigate effects of reductions of haematology during egg-laying, we treated females with PHZ or saline (control) upon completion of their unmanipulated first clutch and removed eggs to induce the production and rearing of a replacement clutch. To investigate effects of reductions of haematology during chick rearing, we treated females during incubation of the unmanipulated first clutch and then monitored the subsequent hatching and rearing of the clutch. 4. Individuals with higher haematocrit and haemoglobin initiated nesting earlier. Furthermore, higher haemoglobin levels during incubation were associated with a greater number of chicks fledged. 5. PHZ treatment prior to egg production resulted in a significant delay in the laying of replacement clutches, but had no effect on provisioning rate or the size or number of chicks fledged. PHZ treatment during incubation and early chick rearing resulted in decreased hatchling mass in all years and a decrease in the size and number of fledglings in one of 2years. The year that the effect of PHZ was observed appeared to be a particularly difficult year, as hatchling mass, brood size at hatching and at fledging were low among control females compared to other years. 6. Our results suggest that a reduction in haematology during reproduction can be functionally significant, but that these costs are context-dependent. DOI

162. Hennin, HL; Bety, J; Legagneux, P; Gilchrist, HG; Williams, TD; Love, OP. (2016) Energetic Physiology Mediates Individual Optimization of Breeding Phenology in a Migratory Arctic Seabird. American Naturalist 188: 434-445 DOI

161. Legagneux, P; Hennin, HL; Gilchrist, HG; Williams, TD; Love, OP; Bety, J. (2016) Unpredictable perturbation reduces breeding propensity regardless of pre-laying reproductive readiness in a partial capital breeder. Journal of Avian Biology 47: 880-886 Unpredictable perturbation reduces breeding propensity regardless of pre-laying reproductive readiness in a partial capital breeder Theoretically, individuals of migratory species should optimize reproductive investment based on a combination of timing of and body condition at arrival on the breeding grounds. A minimum threshold body mass is required to initiate reproduction, and the timing of reaching this threshold is critical because of the trade-off between delaying breeding to gain in condition against the declining value of offspring with later reproductive timing. Long-lived species have the flexibility within their life history to skip reproduction in a given year if they are unable to achieve this theoretical mass threshold. Although the decision to breed or not is an important parameter influencing population dynamics, the mechanisms underlying this decision are poorly understood. Here, we mimicked an unpredictable environmental perturbation that induced a reduction in body mass of Arctic pre-breeding (before the laying period) female common eiders Somateria mollissima; a long-lived migratory seaduck, while controlling for individual variation in the pre-laying physiological reproductive readiness via vitellogenin (VTG) - a yolk-targeted lipoprotein. Our aim was to causally determine the interaction between body condition and pre-laying reproductive readiness (VTG) on breeding propensity by experimentally reducing body mass in treatment females. We first demonstrated that arrival body condition was a key driver of breeding propensity. Secondly, we found that treatment and VTG levels interacted to influence breeding propensity, indicating that our experimental manipulation, mimicking an unpredictable food shortage, reduced breeding propensity, regardless of the degree of pre-laying physiological reproductive readiness (i.e. timing of ovarian follicles recruitment). Our experiment demonstrates that momentary environmental perturbations during the pre-breeding period can strongly affect the decision to breed, a key parameter driving population dynamics. DOI

160. Reers, AR; Eng, ML; Williams, TD; Elliott, JE; Cox, ME; Beischlag, TV. (2016) The Flame-Retardant Tris(1,3-dichloro-2-propyl) Phosphate Represses Androgen Signaling in Human Prostate Cancer Cell Lines. Journal of Biochemical and Molecular Toxicology 30: 249-257 DOI

159. Wong, LIL; Reers, AR; Currier, HA; Williams, TD; Cox, ME; Elliott, JE; Beischlag, TV. (2016) The Effects of the Organic Flame-Retardant 1,2-Dibromo-4-(1,2-dibromoethyl) Cyclohexane (TBECH) on Androgen Signaling in Human Prostate Cancer Cell Lines. Journal of Biochemical and Molecular Toxicology 30: 239-242 DOI

158. Yu, MS; Eng, ML; Williams, TD; Basu, N; Elliottz, JE. (2016) ACUTE EMBRYOTOXIC EFFECTS BUT NO LONG-TERM REPRODUCTIVE EFFECTS OF IN OVO METHYLMERCURY EXPOSURE IN ZEBRA FINCHES (TAENIOPYGIA GUTTATA). Environmental Toxicology and Chemistry 35: 1534-1540 DOI

157. Crossin, GT; Takahashi, A; Sakamoto, KQ; Trathan, PN; Williams, TD. (2015) Habitat selection by foraging macaroni penguins correlates with hematocrit, an index of aerobic condition. Marine Ecology Progress Series 530: 163-176 Habitat selection by foraging macaroni penguins correlates with hematocrit, an index of aerobic condition Biologging; Time-depth recorders; GPS; Telemetry; Parental care; Eudyptes; Ocean temperature Reproductive investment during the chick-rearing period is an important contributor to lifetime fitness. Key to chick-rearing is the success of parental foraging, as food deliveries affect chick growth and survival up until fledging. For seabirds, oceanographic conditions including factors such as sea surface temperature are known to influence foraging decisions, but few studies have examined the physiological variables that might affect those decisions. We used global positioning systems (GPS), time-depth recorders (TDR), and physiological sampling techniques to explore links between ocean temperature, diving behavior, and foraging success in chick-rearing female macaroni penguins Eudyptes chrysolophus. We then explored correlations between these foraging variables and measures of individual physiological condition, specifically aerobic capacity (hematocrit) and metabolic state (corticosterone). In GPS-tracked penguins, 2 principal for aging tactics were observed: penguins made deep dives in cool, near-shore areas surrounding the breeding colony at Bird Island, South Georgia, or they traveled farther to dive shallower in warmer shelf-break areas. TDR-equipped penguins showed similar patterns. Blood sampling of TDR penguins at the onset of trips revealed strong positive correlations between hematocrit and the mean duration of foraging trips, the ocean temperature experienced during these trips, and the relative efficiency of foraging activity in terms of the number of foraging behaviors recorded per dive. These results suggest that aerobic capacity might be an important determinant of for aging trip range, as well as workload. Corticosterone was unrelated to diving behavior, which counters previous studies examining the effects of experimental increases of this hormone on foraging behavior, and we discuss reasons for this disparity. DOI

156. Currier, HA; Letcher, RJ; Williams, TD; Elliott, JE. (2015) Effects of the Bioaccumulative Polybrominated Diphenyl Ether Flame Retardant Congener BDE-47 on Growth, Development, and Reproductive Success in Zebra Finches. Bulletin of Environmental Contamination and Toxicology 94: 140-145 DOI

155. Fowler, MA; Williams, TD. (2015) Individual variation in parental workload and breeding productivity in female European starlings: is the effort worth it? Ecology and Evolution 5: 3585-3599 Individual variation in parental workload and breeding productivity in female European starlings: is the effort worth it? Female parental care; individual variation; provisioning; reproductive success; workload We analyzed individual variation in work load (nest visit rate) during chick-rearing, and the consequences of this variation in terms of breeding productivity, in a highly synchronous breeder, the European starling (Sturnus vulgaris) focusing on female birds. There was marked (10- to 16-fold) variation in total, female and male nest visit rates, among individuals, but individual variation in female nest visit rate was independent of environment (rainfall, temperature) and metrics of individual quality (laying date, clutch size, amount of male provisioning help), and was only weakly associated with chick demand (i.e., day 6 brood size). Female nest visit rate was independent of date and experimentally delayed birds provisioned at the same rate as peak-nesting birds; supporting a lack of effect of date per se. Brood size at fledging was positively but weakly related to total nest visit rate (male+female), with >fivefold variation in nest visit rate for any given brood size, and in females brood size at fledging and chick mass at fledging were independent of female nest visit rate, that is, individual variation in workload was not associated with higher productivity. Nevertheless, nest visit rate in females was repeatable among consecutive days (6-8 posthatching), and between peak (first) and second broods, but not among years. Our data suggest that individual females behave as if committed to a certain level of parental care at the outset of their annual breeding attempt, but this varies among years, that is, behavior is not fixed throughout an individual's life but represents an annually variable decision. We suggest females are making predictable decisions about their workload during provisioning that maximizes their overall fitness based on an integration of information on their current environment (although these cues currently remain unidentified). DOI

154. Perfito, N; Guardado, D; Williams, TD; Bentley, GE. (2015) Social Cues Regulate Reciprocal Switching of Hypothalamic Dio2/Dio3 and the Transition Into Final Follicle Maturation in European Starlings (Sturnus vulgaris). Endocrinology 156: 694-706 DOI

153. Ryan, CP; Dawson, A; Sharp, PJ; Williams, TD. (2015) Uncoupling clutch size, prolactin, and luteinizing hormone using experimental egg removal. General and Comparative Endocrinology 213: 1-8 DOI

152. Steenweg, RJ; Hennin, HL; Bety, J; Gilchrist, HG; Williams, TD; Crossin, GT; Love, OP. (2015) Sources of diel variation in energetic physiology in an Arctic-breeding, diving seaduck. General and Comparative Endocrinology 216: 39-45 DOI

151. Webster, KH; Harr, KE; Bennett, DC; Williams, TD; Cheng, KM; Maisonneuve, F; Elliott, JE. (2015) Assessment of toxicity and coagulopathy of brodifacoum in Japanese quail and testing in wild owls. Ecotoxicology 24: 1087-1101 Assessment of toxicity and coagulopathy of brodifacoum in Japanese quail and testing in wild owls Brodifacoum; Rodenticide; Prothrombin time; Japanese quail; Biomarker; Barn owl Based on detection of hepatic residues, scavenging and predatory non-target raptors are widely exposed to second generation anticoagulant rodenticides (SGARs). A small proportion, generally < 10 %, of tested birds are diagnosed as acutely poisoned. Little is known, however, of sub-lethal effects of SGARs, such as interaction of clotting capacity with traumatic injury. Assessment of coagulation function of birds submitted live to wildlife rehabilitators or veterinarians may provide a means of establishing the proportion of animals suffering sub-lethal coagulopathies, as well as identifying individuals requiring treatment. As a first step in exploring the potential of this approach, we dosed Japanese quail (Coturnix japonica) with the SGAR, brodifacoum, at 0, 0.8, 1.4, 1.9, and 2.5 mg/kg and sampled birds at 1, 3, 5 and 7 days post-dosing. Prothrombin time (PT), which measures the extrinsic coagulation pathway, was significantly prolonged in 98 % of brodifacoum-exposed quail in a dose- and time-dependent manner. 50-fold prolongation of PT occurred at higher brodifacoum dosages and correlated to hemorrhage found at necropsy. Activated clotting time (ACT), a measure of the intrinsic pathway also increased with dose and time. Hemoglobin (Hb) and hematocrit (Hct) decreased dose- and time-dependently at doses a parts per thousand yen1.4 mg/kg with no significant change at 0.8 mg/kg. Reference intervals for PT (10.0-16.2 s), ACT (30-180 s), Hb (9.6-18.4 g/dl), and Hct (34-55 %) were established in Japanese quail. Species-specific reference intervals are required as barn owl PT (17-29 s) and quail PT were different. The proportion of brodifacoum-exposed quail with hemorrhage was not correlated with liver residues, but was correlated with PT, suggesting that this assay is a useful indicator of avian anticoagulant rodenticide exposure. PTs measured in free-living barn owls sampled between April 2009 and August 2010 in the lower Fraser Valley of BC do not suggest significant exposure to SGARs. DOI

150. Williams, TD; Bourgeon, S; Cornell, A; Ferguson, L; Fowler, M; Fronstin, RB; Love, OP. (2015) Mid-winter temperatures, not spring temperatures, predict breeding phenology in the European starling Sturnus vulgaris. Royal Society Open Science 2 DOI

149. Williams, TD; Fowler, MA. (2015) Individual variation in workload during parental care: can we detect a physiological signature of quality or cost of reproduction? Journal of Ornithology 156: S441-S451 Individual variation in workload during parental care: can we detect a physiological signature of quality or cost of reproduction? Parental care; Exercise physiology; Workload; Sturnus vulgaris; Cost of reproduction; Physiological costs How hard do birds work during parental care, chick rearing, or provisioning of their nestlings? And if birds do work hard, can we detect a physiological signature of individual variation in workload ability (perhaps related to 'quality') or costs associated with high workload? Here, we provide a broad conceptual perspective on these questions. Life-history theory predicts (or requires) that (1) parental care is hard work, (2) individuals that invest more in parental care benefit in terms of rearing more, larger, fitter offspring, but that (3) increased investment in parental care comes at a cost: decreased future fecundity and/or survival. However, we start by highlighting studies that are inconsistent with this conventional view, e.g., (1) females often do not pay a survival cost of increased workload (though males do), (2) some (high quality?) individuals appear to maximise numerous life-history traits, and (3) workload during parental care often does not predict productivity. We suggest that an "exercise physiology" perspective on parental care might be informative, but highlight the fact that existing models of exercise often involve conditions very different from that free-living animals experience while foraging (e.g., using forced exercise) and are often divorced from the critical relationship in free-living animals between exercise and acquisition of resources. We briefly review studies looking at physiological effects of workload during parental care in freeliving birds, but again highlight our surprising lack of knowledge in this area especially where experimental manipulation of workload is coupled with comprehensive, physiological analysis. Finally, we make three recommendations for how can we advance the study of physiology of parental care in chick-rearing birds: (1) experimental manipulation of workload, (2) obtaining better measures of workload, for large numbers of known-individuals, and (3) better assessment of physiology of individual quality, and identification of specific metrics of workload-induced 'wear and tear'. DOI

148. Eng, ML; Elliott, JE; Jones, SP; Williams, TD; Drouillard, KG; Kennedy, SW. (2014) AMINO ACID SEQUENCE OF THE AHR1 LIGAND-BINDING DOMAIN PREDICTS AVIAN SENSITIVITY TO DIOXIN LIKE COMPOUNDS: IN VIVO VERIFICATION IN EUROPEAN STARLINGS. Environmental Toxicology and Chemistry 33: 2753-2758 DOI

147. Eng, ML; Elliott, JE; Williams, TD. (2014) An assessment of the developmental toxicity of BDE-99 in the European starling using an integrated laboratory and field approach. Ecotoxicology 23: 1505-1516 DOI

146. Eng, ML; Williams, TD; Letcher, RJ; Elliott, JE. (2014) Assessment of concentrations and effects of organohalogen contaminants in a terrestrial passerine, the European starling. Science of the Total Environment 473: 589-596 Assessment of concentrations and effects of organohalogen contaminants in a terrestrial passerine, the European starling Polybrominated diphenyl ethers; Polychlorinated biphenyls; Organochlorine pesticides; Passerine eggs; Reproductive success; Physiology European starlings (Sturnus vulgar(s) are a valuable model species for the assessment of concentrations and effects of environmental contaminants in terrestrial birds. Polybrominated diphenyl ethers (PBDEs) are found in birds throughout the world, but relatively little is known of their concentrations or effects in free-living terrestrial passerines. We used a nest box population of European starlings to 1) measure the variation in egg concentrations of persistent organohalogen contaminants at an agricultural site, and 2) assess whether individual variation in PBDE concentrations in eggs was related to reproductive parameters, as well as maternal or nestling characteristics including body condition, thyroid hormones, oxidative stress, and hematocrit. As PBDEs were the main contaminant class of interest, we only assessed a subset of eggs for other organohalogen contaminants to establish background concentrations. Exposure to organohalogen contaminants was extremely variable over this relatively small study area. Geometric mean wet weight concentrations (range in brackets) of the major contaminants were 36.5 (12-174) ng/g Sigma DDT (n = 6 eggs) and 10.9 (2-307) ng/g Sigma PBDEs (n = 14). Sigma PCBs at 3.58 (1.5-6.4) ng/g (n = 6) were lower and less variable. There were low levels of other organochlorine (0C) pesticides such as dieldrin (2.02 ng/g), chlordanes (1.11 ng/g) and chlorobenzenes (0.23 ng/g). The only form of DDT detected was p,p'-DDE. The congener profiles of PBDEs and PCBs reflect those of industrial mixtures (i.e. DE-71, Aroclors 1254, 1260 and 1262). For all of the contaminant classes, concentrations detected in eggs at our study site were below levels previously reported to cause effects. Due to small sample sizes, we did not assess the relationship between Sigma PCBs or Sigma OCs and adult or chick condition. We observed no correlative relationships between individual variation in PBDE concentrations in starling eggs and reproductive success, maternal condition, or nestling condition in the corresponding nests. (C) 2014 Elsevier B.V. All rights reserved. DOI

145. Gorman, KB; Williams, TD; Fraser, WR. (2014) Ecological Sexual Dimorphism and Environmental Variability within a Community of Antarctic Penguins (Genus Pygoscelis). PLOS One 9 Ecological Sexual Dimorphism and Environmental Variability within a Community of Antarctic Penguins (Genus Pygoscelis) Background: Sexual segregation in vertebrate foraging niche is often associated with sexual size dimorphism (SSD), i.e., ecological sexual dimorphism. Although foraging behavior of male and female seabirds can vary markedly, differences in isotopic (carbon, delta C-13 and nitrogen, delta N-15) foraging niche are generally more pronounced within sexually dimorphic species and during phases when competition for food is greater. We examined ecological sexual dimorphism among sympatric nesting Pygoscelis penguins asking whether environmental variability is associated with differences in male and female pre-breeding foraging niche. We predicted that all Pygoscelis species would forage sex-specifically, and that higher quality winter habitat, i.e., higher or lower sea ice coverage for a given species, would be associated with a more similar foraging niche among the sexes. Results: P2/P8 primers reliably amplified DNA of all species. On average, male Pygoscelis penguins are structurally larger than female conspecifics. However, chinstrap penguins were more sexually dimorphic in culmen and flipper features than Adelie and gentoo penguins. Adelies and gentoos were more sexually dimorphic in body mass than chinstraps. Only male and female chinstraps and gentoos occupied separate delta N-15 foraging niches. Strong year effects in delta N-15 signatures were documented for all three species, however, only for Adelies, did yearly variation in delta N-15 signatures tightly correlate with winter sea ice conditions. There was no evidence that variation in sex-specific foraging niche interacted with yearly winter habitat quality. Conclusion: Chinstraps were most sexually size dimorphic followed by gentoos and Adelies. Pre-breeding sex-specific foraging niche was associated with overall SSD indices across species; male chinstrap and gentoo penguins were enriched in delta N-15 relative to females. Our results highlight previously unknown trophic pathways that link Pygoscelis penguins with variation in Southern Ocean sea ice suggesting that each sex within a species should respond similarly in pre-breeding trophic foraging to changes in future winter habitat. DOI

144. Love, OP; Madliger, CL; Bourgeon, S; Semeniuk, CAD; Williams, TD. (2014) Evidence for baseline glucocorticoids as mediators of reproductive investment in a wild bird. General and Comparative Endocrinology 199: 65-69 Evidence for baseline glucocorticoids as mediators of reproductive investment in a wild bird Corticosterone; Reproductive investment; Phenotypic flexibility; Reaction norm; Fitness; European starling (Sturnus vulgaris) Determining the mechanisms that mediate investment decisions between current and future reproductive attempts is still a key goal of life-history studies. Since baseline levels of stress hormones (glucocorticoids - GCs) act as predictive and labile regulators of daily energetic balance in vertebrates they remain excellent candidates for mediating investment decisions both within and across reproductive attempts. Using free-living female European starlings (Sturnus vulgaris) we experimentally reduced investment in current reproduction (number of offspring raised in the first brood) to examine whether baseline corticosterone (CORT) acted as a hormonal mediator preparing individuals for a predictable increase in future investment (number of offspring raised in the second brood). Although treatment and control birds raised the same total amount of offspring across two broods, the experimental birds increased reproductive investment in second broods to compensate for the reduced investment in the first brood. Data on both mean and intra-individual changes in baseline CORT support the idea that an increase in baseline CORT between the incubation stages in treatment birds strongly predicted this increase in investment. Importantly, we measured the increase in baseline CORT during late incubation prior to the increase in energetic demand associated with increased reproductive investment in offspring, indicating that flexible within-individual changes in baseline GCs can act as a labile mechanism preparing individuals for predictable increases in reproductive investment. As such, our experimental results indicate that elevated baseline GCs can prepare individuals for investment in energetically expensive life-history stages, rather than simply being elevated as a consequence of increased effort or demand. This suggests that short-term preparative increases in baseline GCs benefit individuals by successfully allowing them to maximize fitness under varying environmental conditions. (C) 2014 Elsevier Inc. All rights reserved. DOI

143. Ryan, CP; Dawson, A; Sharp, PJ; Meddle, SL; Williams, TD. (2014) Circulating breeding and pre-breeding prolactin and LH are not associated with clutch size in the zebra finch (Taeniopygia guttata). General and Comparative Endocrinology 202: 26-34 DOI

142. Tissier, ML; Williams, TD; Criscuolo, F. (2014) Maternal Effects Underlie Ageing Costs of Growth in the Zebra Finch (Taeniopygia guttata). PLOS One 9 DOI

141. Wagner, DN; Green, DJ; Cooper, JM; Love, OP; Williams, TD. (2014) Variation in Plasma Corticosterone in Migratory Songbirds: A Test of the Migration-Modulation Hypothesis. Physiological and Biochemical Zoology 87: 695-703 DOI

140. Crespi, EJ; Williams, TD; Jessop, TS; Delehanty, B. (2013) Life history and the ecology of stress: how do glucocorticoid hormones influence life-history variation in animals? Functional Ecology 27: 93-106 Life history and the ecology of stress: how do glucocorticoid hormones influence life-history variation in animals? PREDICT SURVIVAL PROBABILITIES; MARSUPIAL ANTECHINUS-STUARTII; PHASCOGALE-CALURA MARSUPIALIA; TROUT ONCORHYNCHUS-MYKISS; GALAPAGOS MARINE IGUANAS; RED-TAILED PHASCOGALE; LONG-LIVED SEABIRD; CORTICOSTERONE LEVELS; STEROID-HORMONES; PHYSIOLOGICAL STRESS Glucocorticoids hormones (GCs) are intuitively important for mediation of age-dependent vertebrate life-history transitions through their effects on ontogeny alongside underpinning variation in life-history traits and trade-offs in vertebrates. These concepts largely derive from the ability of GCs to alter energy allocation, physiology and behaviour that influences key life-history traits involving age-specific life-history transitions, reproduction and survival. Studies across vertebrates have shown that the neuroendocrine stress axis plays a role in the developmental processes that lead up to age-specific early life-history transitions. While environmental sensitivity of the stress axis allows for it to modulate the timing of these transitions within species, little is known as to how variation in stress axis function has been adapted to produce interspecific variation in the timing of life-history transitions. Our assessment of the literature confirms that of previous reviews that there is only equivocal evidence for correlative or direct functional relationships between GCs and variation in reproduction and survival. We conclude that the relationships between GCs and life-history traits are complex and general patterns cannot be easily discerned with current research approaches and experimental designs. We identify several future research directions including: (i) integration of proximate and ultimate measures, including longitudinal studies that measure effects of GCs on more than one life-history trait or in multiple environmental contexts, to test explicit hypotheses about how GCs and life-history variation are related and (ii) the measurement of additional factors that modulate the effects of GCs on life-history traits (e.g. GC receptors and binding protein levels) to better infer neurendocrine stress axis actions. Conceptual models of HPA/I axis actions, such as allostatic load and reactive scope, to some extent explicitly predict the role of GCs in a life-history context, but are descriptive in nature. We propose that GC effects on life-history transitions, survival probabilities and fecundity can be modelled in existing quantitative demographic frameworks to improve our understanding of how GC variation influences life-history evolution and GC-mediated effects on population dynamics DOI

139. Crossin, GT; Phillips, RA; Lattin, CR; Romero, LM; Williams, TD. (2013) Corticosterone mediated costs of reproduction link current to future breeding. General and Comparative Endocrinology 193: 112-120 DOI

138. Currier, HA; Letcher, RJ; Williams, TD; Elliott, JE. (2013) An Assessment of In Ovo Toxicity of the Flame Retardant 1,2-Dibromo-4-(1,2-Dibromoethyl) Cyclohexane (TBECH) in the Zebra Finch. Bulletin of Environmental Contamination and Toxicology 91: 455-459 DOI

137. Eens, M; Jaspers, VLB; Van den Steen, E; Bateson, M; Carere, C; Clergeau, P; Costantini, D; Dolenec, Z; Elliott, JE; Flux, J; Gwinner, H; Halbrook, RS; Heeb, P; Mazgajski, TD; Moksnes, A; Polo, V; Soler, JJ; Sinclair, R; Veiga, JP; Williams, TD; Covaci, A; Pinxten, R. (2013) Can starling eggs be useful as a biomonitoring tool to study organohalogenated contaminants on a worldwide scale? Environment International 51: 141-149 Can starling eggs be useful as a biomonitoring tool to study organohalogenated contaminants on a worldwide scale? BROMINATED FLAME RETARDANTS; POLYBROMINATED DIPHENYL ETHERS; PERSISTENT ORGANIC POLLUTANTS; ENDOCRINE-DISRUPTING CHEMICALS; STURNUS-VULGARIS; EUROPEAN STARLINGS; GREAT-LAKES; PARUS-MAJOR; ORGANOCHLORINE PESTICIDES; GLOBAL DISTRIBUTION Large-scale international monitoring studies are important to assess emission patterns and environmental distributions of organohalogenated contaminants (OHCs) on a worldwide scale. In this study, the presence of OHCs was investigated on three continents (Europe, North America and Australasia), using eggs of starlings (Sturnus vulgaris and Sturnus unicolor) to assess their suitability for large-scale monitoring studies. To the best of our knowledge, this is the first study using bird eggs of the same species as a biomonitor for OHCs on an intercontinental scale. We found significant differences in OHC concentrations of the eggs among sampling locations, except for hexachlorocyclohexanes (HCHs). Mean concentrations of sum polychlorinated biphenyls (PCBs) in eggs ranged from 78 26 ng/g lipid weight (lw) in Australia to 2900 +/- 1300 ng/g lw in the United States. The PCB profile was dominated by CB 153 and CB 138 in all locations, except for New Zealand, where the contribution of CB 95, CB 101 and CB 149 was also high. The highest mean sum polybrominated diphenyl ether (PBDE) concentrations were found in Canada (4400 +/- 830 ng/g lw), while the lowest mean PBDE concentrations were measured in Spain (3.7 +/- 0.1 ng/g lw). The PBDE profile in starling eggs was dominated by BDE 47 and BDE 99 in all countries, but in Belgium, the higher brominated PBDEs had a higher contribution compared to other countries. For the organochlorine pesticides (OCPs), dichlorodiphenyltrichloroethanes (DDTs) ranged from 110 +/- 16 ng/g lw in France to 17,000 +/- 3400 ng/g lw in New Zealand, while HCHs and hexachlorobenzene were generally in low concentrations in all sampling locations. Chlordanes were remarkably high in eggs from the United States (2500 +/- 1300 ng/g lw). The OCP profile in all countries was largely dominated by p,p'-DDE. In general, the worldwide trends we observed in starling eggs were in accordance with the literature on human and environmental OHC data, which suggests that there is potential for using starling eggs as a biomonitoring tool on a large geographical scale. (C) 2012 Elsevier Ltd. All rights reserved. DOI

136. Eng, ML; Elliott, JE; Letcher, RJ; Williams, TD. (2013) Individual variation in body burden, lipid status, and reproductive investment is related to maternal transfer of a brominated diphenyl ether (BDE-99) to eggs in the zebra finch. Environmental Toxicology and Chemistry 32: 345-352 DOI

135. Eng, ML; Williams, TD; Elliott, JE. (2013) Developmental exposure to a brominated flame retardant: An assessment of effects on physiology, growth, and reproduction in a songbird, the zebra finch. Environmental Pollution 178: 343-349 DOI

134. Ogden, LJE; Martin, K; Williams, TD. (2013) ELEVATIONAL DIFFERENCES IN ESTIMATED FATTENING RATES SUGGEST THAT HIGH-ELEVATION SITES ARE HIGH-QUALITY HABITATS FOR FALL MIGRANTS. Auk 130: 98-106 ELEVATIONAL DIFFERENCES IN ESTIMATED FATTENING RATES SUGGEST THAT HIGH-ELEVATION SITES ARE HIGH-QUALITY HABITATS FOR FALL MIGRANTS SANDPIPERS CALIDRIS-MAURI; PLASMA-LIPID METABOLITES; WESTERN SANDPIPERS; POSTFLEDGING DISPERSAL; AUTUMN MIGRATION; REFUELING RATES; MASS CHANGES; LAND BIRDS; NEW-WORLD; STOPOVER Many migrant songbird species use high-elevation habitats for stopovers in fall throughout North America, but whether these are good migration habitats as indicated by high fueling rates or other measures has not been previously quantified. At high-quality stopover sites, birds can refuel while maintaining their optimal or preferred migration schedules. We used plasma metabolite analysis to estimate fueling rates of four songbird species during the fall migration period over 3 years at two high-elevation (1,200 m above sea level) and two low-elevation (<25 m above sea level) sites in southwestern British Columbia. For three species with more frugivorous diets during fall the Fox Sparrow (Passerella iliaca), Golden-crowned Sparrow (Zonotrichia atricapilla), and Hermit Thrush (Catharus guttatus)-estimated fattening rates (defined as residual plasma triglyceride levels) were 37-65% higher at high-elevation sites than at low-elevation sites. By contrast, the largely insectivorous and smaller-bodied Orange-crowned Warbler (Oreothlypis celata) had higher estimated fattening rates at low-elevation sites. We found no elevational differences in plasma beta-hydroxybutyrate or glycerol levels except in Hermit Thrushes, which had lower glycerol levels at high elevation. Estimated fattening rates did not differ among the two sparrows and the Hermit Thrush at high-elevation sites, and all three had higher fattening rates than Orange-crowned Warblers. Our data showing strong elevational differences in residual plasma triglyceride levels support the hypothesis that high elevations can be high-quality stopover habitats and, thus, should be considered for protection in songbird management and conservation plans. Received 7 October 2011, accepted 30 August 2012. DOI

133. Palm, EC; Esler, D; Anderson, EM; Williams, TD; Love, OP; Wilson, MT. (2013) Baseline Corticosterone in Wintering Marine Birds: Methodological Considerations and Ecological Patterns. Physiological and Biochemical Zoology 86: 346-353 DOI

132. Stein, RW; Williams, TD. (2013) Extreme Intraclutch Egg-Size Dimorphism in Eudyptes Penguins, an Evolutionary Response to Clutch-Size Maladaptation. American Naturalist 182: 260-270 DOI

131. Winter, V; Elliott, JE; Letcher, RJ; Williams, TD. (2013) Validation of an egg-injection method for embryotoxicity studies in a small, model songbird, the zebra finch (Taeniopygia guttata). Chemosphere 90: 125-131 Validation of an egg-injection method for embryotoxicity studies in a small, model songbird, the zebra finch (Taeniopygia guttata) In ova exposure; Embryotoxicity; Developmental effects; Zebra finch; Flame retardant; PBDE-99 Female birds deposit or 'excrete' lipophilic contaminants to their eggs during egg formation. Concentrations of xenobiotics in bird eggs can therefore accurately indicate levels of contamination in the environment and sampling of bird eggs is commonly used as a bio-monitoring tool. It is widely assumed that maternally transferred contaminants cause adverse effects on embryos but there has been relatively little experimental work confirming direct developmental effects (cf. behaviorally-mediated effects). We validated the use of egg injection for studies of in ovo exposure to xenobiotics for a small songbird model species, the zebra finch (Taeniopygia guttata), where egg weight averages only 1 g. We investigated a) the effect of puncturing eggs with or without vehicle (DMSO) injection on egg fate (embryo development), chick hatching success and subsequent growth to 90 days (sexual maturity), and b) effects of two vehicle solutions (DMSO and safflower oil) on embryo and chick growth. PBDE-99 and -47 were measured in in ovo PBDE-treated eggs, chicks and adults to investigate relationships between putative injection amounts and the time course of metabolism (debromination) of PBDE-99 during early development. We successfully injected a small volume (5 mu L) of vehicle into eggs, at incubation day 0, with no effects on egg or embryo fate and with hatchability similar to that for non-manipulated eggs in our captive-breeding colony (43% vs. 48%). We did find some evidence for an inhibitory effect of DMSO vehicle on post-hatching chick growth, in male chicks only. This method can be used to treat eggs in a dose-dependent, and ecologically-relevant, manner with PBDE-99, based on chemical analysis of eggs, hatchling and adults. (C) 2012 Elsevier Ltd. All rights reserved. DOI

130. Winter, V; Williams, TD; Elliott, JE. (2013) A three-generational study of In ovo exposure to PBDE-99 in the zebra finch. Environmental Toxicology and Chemistry 32: 562-568 DOI

129. Zanette, LY; Hobson, KA; Clinchy, M; Travers, M; Williams, TD. (2013) Food use is affected by the experience of nest predation: implications for indirect predator effects on clutch size. Oecologia 172: 1031-1039 DOI

128. Crossin GT, Poisbleau M, Demongin L, Chastel O, Williams TD, Eens M, Quillfeldt P. (2012) Migratory constraints on yolk precursors limit yolk androgen deposition and underlie a brood reduction strategy in rockhopper penguins. Biol Lett. 2012 Dec 23;8(6):1055-8. Epub 2012 Jul 18. 8: 1055-1058 DOI

127. Crossin, GT; Dawson, A; Phillips, RA; Trathan, PN; Gorman, KB; Adlard, S; Williams, TD. (2012) Seasonal patterns of prolactin and corticosterone secretion in an Antarctic seabird that moults during reproduction. General and Comparative Endocrinology 175: 74-81 DOI

126. Crossin, GT; Phillips, RA; Trathan, PN; Fox, DS; Dawson, A; Wynne-Edwards, KE; Williams, TD. (2012) Migratory carryover effects and endocrinological correlates of reproductive decisions and reproductive success in female albatrosses. General and Comparative Endocrinology 176: 151-157 DOI

125. Crossin, GT; Trathan, PN; Phillips, RA; Gorman, KB; Dawson, A; Sakamoto, KQ; Williams, TD. (2012) Corticosterone Predicts Foraging Behavior and Parental Care in Macaroni Penguins. American Naturalist 180: E31-E41 DOI

124. Crossin, GT; Trathan, PN; Williams, TD. (2012) Potential mode of clutch size determination and follicle development in Eudyptes penguins. Polar Biology 35: 313-317 DOI

123. Eng, ML; Elliott, JE; MacDougall-Shackleton, SA; Letcher, RJ; Williams, TD. (2012) Early Exposure to 2,2 ',4,4 ',5-Pentabromodiphenyl Ether (BDE-99) Affects Mating Behavior of Zebra Finches. Toxicological Sciences 127: 269-276 DOI

122. Vezina, F; Williams, TD; Piersma, T; Morrison, RIG. (2012) Phenotypic compromises in a long-distance migrant during the transition from migration to reproduction in the High Arctic. Functional Ecology 26: 500-512 Phenotypic compromises in a long-distance migrant during the transition from migration to reproduction in the High Arctic arrival biology; basal metabolic rate; breeding; energetics; life-history stages; phenotypic flexibility; physiological conflicts; polar environment; reproduction; thermoregulation 1. Seasonal carry-over effects may be important structuring components of avian life-history cycles. However, little is known on physiological transitions between stages and on phenotypic compromises that may be made at such time to improve fitness. 2. We studied postmigratory body remodelling in red knots (Calidris canutus islandica) arriving on the Arctic breeding grounds. Our objectives were to determine the effects of body reconstruction and preparation for breeding on maintenance energy costs and to determine whether weather conditions can force compromises between functions required for postmigration recovery of body composition, thermoregulation and breeding. 3. During two consecutive springs at the northernmost land on Earth (Alert, Ellesmere Island, Canada, 82 degrees 30' N), we monitored changes in knots post- arrival body stores. Using ultrasonography, we also tracked changes in gizzard size, an indicator of gut size, and pectoral muscle thickness, not only an endogenous protein source but also a thermogenic organ. We measured basal metabolic rate (BMR) throughout reconstruction and compared it with BMR of nonbreeding red knots wintering in the Dutch Wadden Sea. 4. Arriving knots faced temperatures up to 13 degrees C lower than during midwinter. Birds arrived with large body stores and pectoral muscles, which declined in size while they grew their gizzard and prepared for breeding. BMR at arrival was indistinguishable from winter BMR and increased linearly throughout reconstruction. BMR increased up to 69% faster in females than males, likely due to the development of their reproductive organs. 5. Birds had lower body stores but larger muscles in the colder year, and muscle loss was correlated with the warming of spring temperatures. Therefore, muscles would not only serve as a nutrient source, but their thermogenic function could also provide the flexibility to cope with high thermostatic costs in the spring. However, retaining muscles for shivering may limit protein recirculation and delay the onset of breeding. 6. Postmigratory recovery therefore involves significant energy costs and arriving birds likely have to make physiological compromises, depending on spring conditions, which may impact on fitness. Although this period is clearly critical in the life cycle of red knots, it is one of the least understood life- history stages in Arctic- breeding shorebirds. DOI

121. Williams, TD. (2012) Hormones, life-history, and phenotypic variation: Opportunities in evolutionary avian endocrinology. General and Comparative Endocrinology 176: 286-295 Hormones, life-history, and phenotypic variation: Opportunities in evolutionary avian endocrinology Phenotypic variation; Breeding; Clutch size; Hormonal pleiotropy; Hormonal conflict Life-histories provide a powerful, conceptual framework for integration of endocrinology, evolutionary biology and ecology. This has been a commonly articulated statement but here I show, in the context of avian reproduction, that true integration of ultimate and proximate approaches has been slow. We have only a rudimentary understanding of the physiological and hormonal basis of phenotypic variation in (a) reproductive traits that contribute most to individual variation in lifetime fitness in birds (e.g. laying date, clutch size, parental effort) and (b) trade-offs that link these traits or that link reproduction to other life stages (e.g. migration, molt). I suggest that some reasons for this relative lack of progress include (a) an increasingly reductionist and centralist (upstream) focus which is more and more removed from ecological/evolutionary context, and from peripheral (downstream) mechanisms that actually determine how phenotypes work (b) a long-standing male-bias in experimental studies, even though the key reproductive traits which contribute most to variation in fitness are female-specific traits (e.g. onset of vitellogenesis, egg size or number). Endocrine systems provide strong candidate mechanisms for regulation of phenotypic variation in single traits, and two endocrine concepts capture the essence of life-history trade-offs: (a) hormonal 'pleiotropy', when single hormones have both positive and negative effects on multiple physiological systems and (b) hormonal conflict between regulatory systems required for different but over-lapping or linked life-history stages. I illustrate these ideas with examples of reproductive anemia, migration-reproduction overlap, and molt-breeding overlap, to highlight some of the tremendous opportunities that exist for comparative endocrinologists to contribute to mechanistic studies of avian reproduction in an evolutionary context. (C) 2011 Elsevier Inc. All rights reserved. DOI

120. Williams, TD; Fronstin, RB; Otomo, A; Wagner, E. (2012) Validation of the use of phenylhydrazine hydrochloride (PHZ) for experimental manipulation of haematocrit and plasma haemoglobin in birds. Ibis 154: 21-29 DOI

119. Bourgeon, S; Guindre-Parker, S; Williams, TD. (2011) Effects of Sibling Competition on Growth, Oxidative Stress, and Humoral Immunity: A Two-Year Brood-Size Manipulation. Physiological and Biochemical Zoology 84: 429-437 DOI

118. Love, OP; Williams, TD. (2011) Manipulating developmental stress reveals sex-specific effects of egg size on offspring phenotype. Journal of Evolutionary Biology 24: 1497-1504 Manipulating developmental stress reveals sex-specific effects of egg size on offspring phenotype STARLING STURNUS-VULGARIS; FLUCTUATING ASYMMETRY; FLIGHT PERFORMANCE; REARING CONDITIONS; REPRODUCTIVE INVESTMENT; HAEMATOPUS-OSTRALEGUS; COMPENSATORY GROWTH; IMMUNE-RESPONSE; TIT NESTLINGS; SURVIVAL The general lack of experimental evidence for strong, positive effects of egg size on offspring phenotype has led to suggestions that avian egg size is a neutral trait. To better understand the functional significance of intra-specific variation in egg size as a determinant of offspring fitness within a life-history (sex-specific life-history strategies) and an environmental (poor rearing conditions) context, we experimentally increased developmental stress (via maternal feather-clipping) in the sexually size-dimorphic European starling (Sturnus vulgaris) and measured phenotypic traits in offspring across multiple biological scales. As predicted by life-history theory, sons and daughters had different responses when faced with developmental stress and variation in egg size. In response to developmental stress, small egg size in normally faster-growing sons was associated with catch-up growth prior to attaining larger adult size, resulting in a reduction in developmental stability. Daughters apparently avoided this developmental instability by reducing growth rate and eventual adult body mass and size. Interestingly, large egg size provided offspring with greater developmental flexibility under poor growth conditions. Large-egg sons and daughters avoided the reduction in developmental stability, and daughters also showed enhanced escape performance during flight trials. Furthermore, large egg size resulted in elevated immune responses for both sexes under developmental stress. These findings show that there can be significant, but complex, context-specific effects of egg size on offspring phenotype at least up to fledging, but these can only be demonstrated by appreciating variation in the quality of the offspring environment and life histories. Results are therefore consistent with egg size playing a significant role in shaping the phenotypic outcome of offspring in species that show even greater intra-specific variation in egg size than starlings. DOI

117. BLIGHT, L.K., BERTRAM, D.F., WILLIAMS, T.D. & COWEN, L. (2010) Interannual variation in egg neglect and incubation routine of Rhinoceros Auklets Cerorhinca monocerata during the 1998-1999 El Niño / La Niña events. Marine Ornithology 38: 11-15 Link

116. Cesh, LS; Elliott, KH; Quade, S; McKinney, MA; Maisoneuve, F; Garcelon, DK; Sandau, CD; Letcher, RJ; Williams, TD; Elliott, JE. (2010) POLYHALOGENATED AROMATIC HYDROCARBONS AND METABOLITES: RELATION TO CIRCULATING THYROID HORMONE AND RETINOL IN NESTLING BALD EAGLES (HALIAEETUS LEUCOCEPHALUS). Environmental Toxicology and Chemistry 29: 1301-1310 POLYHALOGENATED AROMATIC HYDROCARBONS AND METABOLITES: RELATION TO CIRCULATING THYROID HORMONE AND RETINOL IN NESTLING BALD EAGLES (HALIAEETUS LEUCOCEPHALUS) Contaminants; Thyroid hormone; Retinol; Bald eagle; PCBs Polyhalogenated aromatic hydrocarbons are global contaminants that are often considered to be endocrine disruptors and include 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (p,p'-DDE), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). The present study examined these compounds and their hydroxylated metabolites or analogues and relationships with circulating thyroid hormones and retinols in plasma from nestling and adult bald eagles in British Columbia, Canada. and California, USA. We also compared our results with published data. Thyroxine (T4) decreased with Sigma PCB and CB153 in nestling bald eagles. which was congruent with results from nine of 14 other published avian laboratory and field studies. Free thyroid hormone levels also decreased with CB-153 and hydroxylated PCBs (OH-PCBs). Retinol increased with CBI 18 and CB180 in nestling eagles, decreased with OH-PCBs in a subset of nestlings, and decreased in 7 of 12 PCB published studies. Thyroxine decreased with p,p'-DDE for nestlings and with data reported in one of five other published studies. In our samples, plasma retinol, triiodothyronine (T3), and T4 were independent of Sigma PBDEs, whereas Sigma OH-PBDEs were weakly but significantly correlated with increases in T3 and retinol. Adult bald eagles showed no relationship between contaminants and thyroid hormones, which is consistent with other studies of long-lived birds, perhaps because adult birds have time to adjust to contaminant levels. Measurement of circulating thyroid hormones appears to be a more useful biomarker than retinols, given the more consistent response of T4 to PCBs here and reported in the literature. We conclude that current environmental exposures to PCBs in British Columbia and in southern California are associated with significant decreases in T4, suggesting a potential negative effect on the endocrine system of nestling bald eagles. Environ. Toxicol. Chem. 2010;29:1301 1310. (C) 2010 SETAC DOI

115. Crossin, GT; Trathan, PN; Phillips, RA; Dawson, A; Le Bouard, F; Williams, TD. (2010) A Carryover Effect of Migration Underlies Individual Variation in Reproductive Readiness and Extreme Egg Size Dimorphism in Macaroni Penguins. American Naturalist 176: 357-366 DOI

114. Crossin, GT; Trathan, PN; Phillips, RA; Williams, TD. (2010) Trade-off between migration and reproduction, and the physiological basis of egg size dimorphism in Macaroni penguins. Integrative and Comparative Biology 50: E36-E36

113. Eng, ML; Letcher, RJ; Macdougall-Shackleton, SA; Elliott, JE; Williams, TD. (2010) Effects of early exposure to a brominated flame retardant (PBDE-99) on physiology and behaviour in zebra finches. Integrative and Comparative Biology 50: E51-E51

112. Kordonowy, LL; McMurtry, JP; Williams, TD. (2010) Variation in plasma leptin-like immunoreactivity in free-living European starlings (Sturnus vulgaris). General and Comparative Endocrinology 166: 47-53 DOI

111. Salvante, KG; Vezina, F; Williams, TD. (2010) Evidence for within-individual energy reallocation in cold-challenged, egg-producing birds. Journal of Experimental Biology 213: 1991-2000 DOI

110. Travers, M; Clinchy, M; Zanette, L; Boonstra, R; Williams, TD. (2010) Indirect predator effects on clutch size and the cost of egg production. Ecology Letters 13: 980-988 DOI

109. Wagner, DN; Green, D; Cooper, JM; Beauchesne, S; Williams, TD. (2010) Impact of water level management on the condition of migratory songbirds. Integrative and Comparative Biology 50: E309-E309

108. Willie, J; Travers, M; Williams, TD. (2010) Female Zebra Finches (Taeniopygia guttata) Are Chronically but Not Cumulatively "Anemic" during Repeated Egg Laying in Response to Experimental Nest Predation. Physiological and Biochemical Zoology 83: 119-126 Female Zebra Finches (Taeniopygia guttata) Are Chronically but Not Cumulatively "Anemic" during Repeated Egg Laying in Response to Experimental Nest Predation STARLING STURNUS-VULGARIS; HEMATOCRIT VALUES; BODY CONDITION; CLUTCH SIZE; DYNAMICS; SPARROWS; COSTS; MANIPULATIONS; REPEATABILITY; REPRODUCTION Recently it has been recognized that reproduction itself, or the regulatory processes controlling reproduction, might contribute to physiological costs of reproduction. Reproductive anemia, a decrease in hematocrit and hemoglobin concentration, might provide one such mechanism underlying the costs of egg production in birds. In this study, we investigated the effect of repeated cycles of egg production in response to experimental nest predation (egg removal) on hematological traits in female zebra finches (Taeniopygia guttata). We predicted that if the negative effect of egg production on hematocrit and hemoglobin concentration was cumulative, with anemia being proportional to reproductive effort, then females laying more clutches, or laying successive clutches without recovery during incubation, would show greater reproductive anemia. In contrast, if females maintain hematocrit and hemoglobin concentration at some minimum functional level independent of reproductive effort, then there should be no difference in hematological traits among females laying two or more successive clutches. Our results supported the second of these hypotheses: egg-laying females had reduced hematocrit (-7.5%) and hemoglobin concentrations (-10%), but the extent of reproductive anemia did not differ among females laying either two or three successive clutches, with or without recovery during incubation, or in females laying 7-21 eggs. Females maintained low hematocrit and hemoglobin for 20-35 d, and we suggest that prolonged periods of anemia might be common and functionally important in free-living birds, for example, where females produce multiple successive clutches in response to high levels of nest predation or where they initiate a second clutch while still rearing first brood chicks. DOI

107. Caro, SP; Charmantier, A; Lambrechts, MM; Blondel, J; Balthazart, J; Williams, TD. (2009) Local adaptation of timing of reproduction: females are in the driver's seat. Functional Ecology 23: 172-179 DOI

106. Chin, EH; Love, OP; Verspoor, JJ; Williams, TD; Rowley, K; Burness, G. (2009) Juveniles exposed to embryonic corticosterone have enhanced flight performance. Proceedings of the Royal Society B-Biological Sciences 276: 499-505 DOI

105. Gorman, KB; Esler, D; Walzem, RL; Williams, TD. (2009) Plasma Yolk Precursor Dynamics during Egg Production by Female Greater Scaup (Aythya marila): Characterization and Indices of Reproductive State. Physiological and Biochemical Zoology 82: 372-381 DOI

104. Han, D; Haunerland, NH; Williams, TD. (2009) Variation in yolk precursor receptor mRNA expression is a key determinant of reproductive phenotype in the zebra finch (Taeniopygia guttata). Journal of Experimental Biology 212: 1277-1283 DOI

103. JANSSEN, M.H., ARCESE, P., KYSER, T.K., BERTRAM, D.F., MCFARLANE TRANQUILLA, L., WILLIAMS, T.D. & NORRIS, R.D. (2009) Pre-breeding diet, condition, and timing of breeding in a threatened seabird, the Marbled Murrelet Brachyramphus marmoratus. Marine Ornithology 37: 33-40. Pre-breeding diet, condition, and timing of breeding in a threatened seabird, the Marbled Murrelet Brachyramphus marmoratus. Murrelets; Marbled Murrelets; Marbled Murrelets Brachyramphus marmoratus are small, threatened seabirds that nest in old growth coniferous forests along the west coast of North America and spend most of their lives in nearshore waters. Recent evidence suggests that long term declines in pre-breeding trophic feeding level may be associated with reduced reproductive success. To test the hypothesis that pre-breeding trophic feeding level positively influences breeding success, we investigated relationships between timing of breeding, female body condition, and pre-breeding trophic feeding level. We predicted that females feeding on higher trophic level prey prior to breeding would be in better condition, and initiate egg production earlier, than females feeding on lower trophic level prey. Egg producing females were identified based on elevated yolk precursor (vitellogenin) levels, and diet composition was inferred using stable-carbon (δ13C) and -nitrogen (δ15N) analysis of murrelet and prey tissues during the pre-breeding seasons of 1999, 2000, 2006, and 2007 in Desolation Sound, British Columbia. Contrary to our predictions, females feeding on a higher proportion of low trophic level prey in 2007 were in better condition and more likely to produce an egg early in the breeding season. However, differences in pre-breeding diet between egg-producing females and non-egg producers were not consistent among years. Although our results suggest that low trophic level prey in pre-breeding diet promoted egg production and breeding success in 2007, this was likely not the case in others years studied. To reconcile results presented here and previous work on diet composition and breeding success in the Marbled Murrelet, we propose an alternative hypothesis of diet quality incorporating optimal foraging theory, whereby the net energy gain from feeding on a prey type is a function of its relative availability. Link

102. Love, OP; Gilchrist, HG; Bety, J; Wynne-Edwards, KE; Berzins, L; Williams, TD. (2009) Using life-histories to predict and interpret variability in yolk hormones. General and Comparative Endocrinology 163: 169-174 Using life-histories to predict and interpret variability in yolk hormones CORTICOSTERONE LEVELS; MATERNAL ANDROGENS; STRESS HORMONES; PASSERINE BIRDS; EVOLUTION; BENEFITS; EGGS; TESTOSTERONE; REPRODUCTION; INVESTMENT Variation in yolk hormones is assumed to provide the plasticity necessary for mothers to individually optimize reproductive decisions via changes in offspring phenotype, the benefit being to maximise fitness. However, rather than routinely expecting adaptive variation within all species, the pattern and magnitude of yolk hormone deposition should theoretically relate to variation in life-histories. Here we present data on intra-clutch variation in yolk corticosterone in three species along a developmental continuum (European starling (Sturnus vulgaris): fully altricial; black guillemot (Cepphus grylle): semi-precocial; common eider (Somateria mollissima): fully precocial) to examine how and why variation in life-histories might relate to the evolution of variation in yolk steroids. Starlings and guillemots showed a significant increase in yolk corticosterone across the laying sequence; however, we found no pattern within eider clutches. Moreover, starlings showed the largest difference (94.6%) in yolk corticosterone between first- and last-laid eggs, whereas guillemots showed a moderate difference (58.9%). Despite these general species-specific patterns, individuals showed marked variation in the intra-clutch patterns of yolk corticosterone within each species indicating potential differences in intra-clutch flexibility among females. It is well documented that exposure to elevated yolk glucocorticoids reduces offspring quality at birth/hatching in many taxa and it has therefore been proposed that elevated yolk levels may modulate offspring competition and/or facilitate brood reduction under harsh conditions in birds. Our data suggests that intra-clutch variation in yolk corticosterone has the potential to act as an adaptive maternal effect in species where modulation of competition between nest-bound offspring would benefit mothers (starlings and guillemots). However, in precocial species where mothers would not benefit from a modulation of offspring quality, intra-clutch variation in yolk hormones may play little or no adaptive role. While future phylogenetically-controlled studies will be helpful in examining questions of adaptive mechanisms once more data on yolk corticosterone becomes available, our results nonetheless suggest that research on the evolutionary role of yolk hormones can benefit by a prior! incorporating species-specific life-history-driven hypotheses. (C) 2008 Elsevier Inc. All rights reserved. DOI

101. Vezina, F; Love, OP; Lessard, M; Williams, TD. (2009) Shifts in Metabolic Demands in Growing Altricial Nestlings Illustrate Context-Specific Relationships between Basal Metabolic Rate and Body Composition. Physiological and Biochemical Zoology 82: 248-257 DOI

100. Wada, H; Salvante, KG; Wagner, E; Williams, TD; Breuner, CW. (2009) Ontogeny and Individual Variation in the Adrenocortical Response of Zebra Finch (Taeniopygia guttata) Nestlings. Physiological and Biochemical Zoology 82: 325-331 DOI

99. Williams, TD; Vezina, F; Speakman, JR. (2009) Individually variable energy management during egg production is repeatable across breeding attempts. Journal of Experimental Biology 212: 1101-1105 DOI

98. Albert, C; Williams, TD; Morrissey, CA; Lai, VWM; Cullen, WR; Elliott, JE. (2008) Tissue uptake, mortality, and sublethal effects of monomethylarsonic acid (MMA(V)) in nestling zebra finches (Taeniopygia guttata). Journal of Toxicology and Environmental Health-Part A-Current Issues 71: 353-360 DOI

97. Albert, C.A., T.D. Williams, V. Lai, W.R. Cullen, C.A. Morrissey and J.E. Elliott. (2008) Dose dependant uptake, elimination and toxicity of monosodium methanearsonate (MSMA) in adult Zebra Finches (Taeniopygia guttata). Environmental Toxicology and Chemistry 27: 605-611.

96. Bentzen, RL; Powell, AN; Williams, TD; Kitaysky, AS. (2008) Characterizing the nutritional strategy of incubating king eiders Somateria spectabilis in northern Alaska. Journal of Avian Biology 39: 683-690 DOI

95. Bond, JC; Esler, D; Williams, TD. (2008) Breeding propensity of female harlequin ducks. Journal of Wildlife Management 72: 1388-1393 DOI

94. Cesh, LS; Williams, TD; Garcelon, DK; Elliott, JE. (2008) Patterns and trends of chlorinated hydrocarbons in nestling bald eagle (Haliaeetus leucocephalus) plasma in British Columbia and southern California. Archives of Environmental Contamination and Toxicology 55: 496-502 DOI

93. Gorman, K.B., D. Esler, P.L. Flint and T.D. Williams. (2008) Nutrient-reserve dynamics during egg production by female Greater Scaup (Aythya marila): relationships with timing of reproduction. Auk 125: 384-394. Link

92. Love, OP; Salvante, KG; Dale, J; Williams, TD. (2008) Specific variability in the immune system across life-history stages. American Naturalist 172: E99-E112 Specific variability in the immune system across life-history stages cell-mediated immunity; life-history theory; sex-specific differences; individual variation; repeatability; zebra finch (Taeniopygia guttata) Organisms theoretically manage their immune systems optimally across their life spans to maximize fitness. However, we lack information on ( 1) how the immune system is managed across life-history stages, ( 2) whether the sexes manage immunity differentially, and ( 3) whether immunity is repeatable within an individual. We present a within-individual, repeated-measures experiment examining life-history stage variation in the inflammatory immune response in the zebra finch (Taeniopygia guttata). In juveniles, age-dependent variation in immune response differed in a sex-and context-specific manner, resulting in no repeatability across stages. In adults, females displayed little stage-dependent variation in immune response when laying while receiving a high-quality ( HQ) diet; however, laying while receiving a low-quality (LQ) diet significantly reduced both immune responses and reproductive outputs in amanner consistent with a facultative (resource-driven) effect of reproduction on immunity. Moreover, a reduced immune response in females who were raising offspring while receiving an HQ diet suggests a residual effect of the energetic costs of reproduction. Conversely, adult males displayed no variation in immune responses across stages, with high repeatability from the nonbreeding stage to the egg-laying stage, regardless of diet quality ( HQ diet,; LQ diet,). r = 0.51 r = 0.42 Females displayed high repeatability when laying while receiving the HQ diet (r = 0.53); however, repeatability disappeared when individuals received the LQ diet. High-response females receiving the HQ diet had greater immune flexibility than did low-response females who were laying while receiving the LQ diet. Data are consistent with immunity being a highly plastic trait that is sex-specifically modulated in a context-dependent manner and suggest that immunity at one stage may provide limited information about immunity at future stages. DOI

91. Love, OP; Williams, TD. (2008) The adaptive value of stress-induced phenotypes: Effects of maternally derived corticosterone on sex-biased investment, cost of reproduction, and maternal fitness. American Naturalist 172: E135-E149 The adaptive value of stress-induced phenotypes: Effects of maternally derived corticosterone on sex-biased investment, cost of reproduction, and maternal fitness yolk corticosterone; maternal effects; sex allocation; cost of reproduction; plasticity; maternal fitness The question of why maternal stress influences offspring phenotype is of significant interest to evolutionary physiologists. Although embryonic exposure to maternally derived glucocorticoids (i.e., corticosterone) generally reduces offspring quality, effects may adaptively match maternal quality with offspring demand. We present results from an interannual field experiment in European starlings (Sturnus vulgaris) designed explicitly to examine the fitness consequences of exposing offspring to maternally derived stress hormones. We combined a manipulation of yolk corticosterone (yolk injections) with a manipulation of maternal chick-rearing ability (feather clipping of mothers) to quantify the adaptive value of corticosterone-induced offspring phenotypes in relation to maternal quality. We then examined how corticosterone-induced "matching" within this current reproductive attempt affected future fecundity and maternal survival. First, our results provide support that low-quality mothers transferring elevated corticosterone to eggs invest in daughters as predicted by sex allocation theory. Second, corticosterone-mediated sex-biased investment resulted in rapid male-biased mortality resulting in brood reduction, which provided a better match between maternal quality and brood demand. Third, corticosterone-mediated matching reduced investment in current reproduction for low-quality mothers, resulting in fitness gains through increased survival and future fecundity. Results indicate that the transfer of stress hormones to eggs by low-quality mothers can be adaptive since corticosterone-mediated sex-biased investment matches the quality of a mother to offspring demand, ultimately increasing maternal fitness. Our results also indicate that the branding of the proximate effects of maternal glucocorticoids on offspring as negative ignores the possibility that short-term phenotypic changes may actually increase maternal fitness. DOI

90. Love, OP; Williams, TD. (2008) Plasticity in the adrenocortical response of a free-living vertebrate: The role of pre- and post-natal developmental stress. Hormones and Behavior 54: 496-505 Plasticity in the adrenocortical response of a free-living vertebrate: The role of pre- and post-natal developmental stress corticosterone; stress response; maternal effects; yolk hormones; body condition; predictive adaptive responses; developmental plasticity Optimal functioning of the hypothalamo-pituitary-adrenal (HPA) axis is paramount to maximizing fitness in vertebrates. Research in laboratory mammals has suggested that maternally-induced stress can cause significant variation in the responsiveness of an offspring's HPA axis involving both pre- and post-natal developmental mechanisms. However, very little is known regarding effects of maternal stress on the variability of offspring adrenocortical functioning in free-living vertebrates. Here we use an experimental approach that independently lowers the quality of both the pre- and post-natal developmental environment to examine programming and plasticity in the responsiveness of the HPA axis in fledglings of a free-living passerine, the European starling (Sturnus vulgaris). We found that mimicking a hormonal signal of poor maternal condition via an experimental prenatal increase in yolk corticosterone decreased the subsequent responsiveness of the HPA axis in fledglings. Conversely, decreasing the quality of the post-natal developmental environment (by decreasing maternal provisioning capability via a maternal feather-clipping manipulation) increased subsequent responsiveness of the HPA axis in fledglings, apparently through direct effects on nestling body condition. The plasticity of these responses was sex-specific with smaller female offspring showing the largest increase in HPA reactivity. We suggest that pre-natal, corticosterone-induced, plasticity in the HPA axis may be a 'predictive adaptive response' (PAR): a form of adaptive developmental plasticity where the advantage of the induced phenotype is manifested in a future life-history stage. Further, we introduce a new term to define the condition-driven post-natal plasticity of the HPA axis to an unpredictable post-natal environment, namely a 'reactive adaptive response' (RAR). This study confirms that the quality of both the pre- and post-natal developmental environment can be a significant source of variation in the responsiveness of the HPA axis, and provides a frame-work for examining ecologically-relevant sources of stress-induced programming and plasticity in this endocrine system in a free-living vertebrate, respectively. (C) 2008 Elsevier Inc. All rights reserved. DOI

89. Love, OP; Wynne-Edwards, KE; Bond, L; Williams, TD. (2008) Determinants of within- and among-clutch variation in yolk corticosterone in the European starling. Hormones and Behavior 53: 104-111 Determinants of within- and among-clutch variation in yolk corticosterone in the European starling corticosterone; yolk hormones; maternal effects; nesting density; maternal condition; laying order; European starling (Sturnus vulgaris) Maternal glucocorticoids are known to affect offspring phenotype in numerous vertebrate taxa. In birds, the maternal transfer of corticosterone to eggs was recently proposed as a hormonal mechanism by which offspring phenotype is matched to the relative quality of the maternal environment. However, current hypotheses lack supporting information on both intra- and inter-clutch variation in yolk corticosterone for wild birds. As such, we examined variation in yolk corticosterone levels in a wild population of European starlings (Sturnus vulgaris). Maternal condition, clutch size and nesting density were all negatively related to yolk conicosterone deposition, females with high condition indices, those laying larger clutches and those nesting in high-density associations deposited lower amounts of the lion-none into eggs than those with low condition indices, laying small clutches and nesting in isolation. Alternatively, we found no effects of maternal age or human disturbance on yolk corticosterone deposition. Intra-clutch variation of yolk corticosterone was significant, with levels increasing across the laying sequence in all clutch sizes examined, with the difference between first and last-laid eggs being greater in large versus small clutches. Given the reported effects of yolk corticosterone on offspring size and growth, intra-clutch variation in yolk corticosterone has the potential to alter the competitive environment within a brood. Furthermore, our results indicate that variation in yolk corticosterone can originate from variation in both the mother's quality as well as the quality of her breeding environment. The presence of inter-female variation in particular is an important pre-requisite in testing whether the exposure of offspring to maternally-derived corticosterone is a mechanistic link between offspring phenotypic plasticity and maternal quality. (c) 2007 Elsevier Inc. All rights reserved. DOI

88. Pomeroy, A.C., D.A. Acevedo Seaman, R.W. Butler, R.W. Elner, T.D. Williams and R.C. Ydenberg. (2008) Feeding-danger tradeoffs underlie stopover site selection by migrants. Avian Conservation and Ecology - Écologie et Conservation des Oiseaux 3(1): 7 Link

87. Pomeroy, AC; Seaman, DAA; Butler, RW; Elner, RW; Williams, TD; Ydenberg, RC. (2008) Feeding-Danger Trade-Offs Underlie Stopover Site Selection by Migrants. Avian Conserv. Ecol. 3

86. Wada, H; Salvante, KG; Stables, C; Wagner, E; Williams, TD; Breuner, CW. (2008) Adrenocortical responses in zebra finches (Taeniopygia guttata): Individual variation, repeatability, and relationship to phenotypic quality. Hormones and Behavior 53: 472-480 Adrenocortical responses in zebra finches (Taeniopygia guttata): Individual variation, repeatability, and relationship to phenotypic quality adrenocortical response; individual variation; phenotypic quality; Theniopygia guttata Although individual variation is a key requirement for natural selection, little is known about the magnitude and patterns of individual variation in endocrine systems or the functional significance of that variation. Here we describe (1) the extent and repeatability of inter-individual variation in adrenocortical responses and (2) its relationship to sex-specific phenotypic quality, such as song duration and frequency and timing of egg laying. We measured adrenocortical responses to a standardized stressor in zebra finches (Taeniopygia guttata) at two life history stages: similar to day 16 (nestlings) and 3 months of age (sexually mature adults). Subsequently, we assessed phenotypic (reproductive) quality of all individuals as adults. Marked inter-individual variation in the adrenocortical response was seen in both sexes and ages, e.g., stress-induced corticosterone ranged from 2.2 to 62.5 ng/mL in nestlings and 5.0-64.0 ng/mL in adults. We found sex differences in (a) inter-individual variation in the adrenocortical response, (b) repeatability, and (c) relationships between corticosterone levels and phenotypic quality. In males, variation in nestling corticosterone was weakly but positively correlated with brood size and negatively correlated with nestling mass (though this relationship was dependent on one individual). There was no significant correlation of adrenocortical responses between two stages in males and adult phenotypic quality was significantly correlated only with adult corticosterone levels. In contrast, in females there was no relationship between nestling corticosterone and brood size or mass but adrenocortical response was repeatable between two stages (r(2) =0.413). Phenotypic quality of adult females was correlated with nestling baseline and adrenocortical response. (c) 2008 Elsevier Inc. All rights reserved. DOI

85. Wagner, EC; Prevolsek, JS; Wynne-Edwards, KE; Williams, TD. (2008) Hematological changes associated with egg production: estrogen dependence and repeatability. Journal of Experimental Biology 211: 400-408 DOI

84. Wagner, EC; Stables, CA; Williams, TD. (2008) Hematological changes associated with egg production: direct evidence for changes in erythropoiesis but a lack of resource dependence? Journal of Experimental Biology 211: 2960-2968 Hematological changes associated with egg production: direct evidence for changes in erythropoiesis but a lack of resource dependence? anemia; cost of reproduction; egg production; erythropoiesis; estrogen; zebra finch Reductions in hematological parameters among laying birds are well reported, but the cause of this anemia is not known. We tested specific predictions generated from several, non-mutually exclusive hypotheses for mechanisms underlying reproductive anemia associated with egg production (hemodilution, transient suppression of erythropoiesis, resource dependence) in relation to (1) the time-course of development and recovery from anemia, (2) changes in specific hematological traits, and (3) the effect of diet quality, in female zebra finches (Taeniopygia guttata). Female zebra finches showed marked decreases in hematocrit (similar to 6%), red blood cell counts (similar to 8%), and plasma hemoglobin concentration (similar to 9%) during egg production, even on a high-quality ad libitum diet, consistent with an effect of hemodilution associated with yolk precursor production. However, our results provide strong support for the hypothesis that erythropoiesis is transiently suppressed during egg-laying and that the recovery from anemia is relatively long-lasting, extending through incubation and hatching periods. Decreased hematocrit, red blood cell counts, and hemoglobin concentration did not recover at clutch completion, but showed evidence of recovery to baseline pre-breeding levels at hatching. More importantly, there was significant time-dependent variation in the proportion of reticulocytes, which increased at clutch completion but peaked at hatching 10-12 days after clutch completion, and in mean red blood cell volume, which showed a significant increase at clutch completion; consistent with enhanced production and release of larger immature cells into the circulation following suppression of erythropoiesis. Finally, we found no evidence for resource dependence of anemia associated with egg production in relation to diet quality, i.e. exogenous lipid and protein resources available to the laying female. This study demonstrates that transient suppression of erythropoiesis and, subsequently, increased reticulocytosis, are key components of reproductive anemia in egg-laying females. DOI

83. Williams, TD. (2008) Individual variation in endocrine systems: moving beyond the 'tyranny of the Golden Mean'. Philosophical Transactions of the Royal Society B-Biological Sciences 363: 1687-1698 DOI

82. Wingfield, JC; Visser, ME; Williams, TD. (2008) Introduction. Integration of ecology and endocrinology in avian reproduction: a new synthesis. Philosophical Transactions of the Royal Society B-Biological Sciences 363: 1581-1588 Introduction. Integration of ecology and endocrinology in avian reproduction: a new synthesis ecology; endocrinology; evolution; global warming; climate change; maternal effects Birds are some of the most familiar organisms of global ecosystems. Changes in the visibility and abundance of birds are therefore excellent indicators of population and physiological responses to habitat changes and are a major focus for public concern about detrimental environmental changes. In order to understand how birds respond to these challenges, it is essential to determine how the environment affects reproduction under natural conditions. The continuum from environmental variables (cues) to reproductive life-history traits depends upon a cascade of neural and physiological processes that determine the extent and rate at which birds will be able to adapt to changes in their environment. For a full understanding of this ability to adapt, ecologists and endocrinologists need to collaborate and build a common framework. The objective of this theme issue is to bring together a series of papers addressing how evolutionary ecologists and endocrinologists can collaborate directly using avian reproduction as a model system. First, we address the need to integrate ecology and endocrinology and what benefits to biological knowledge will be gained. The papers collected in this issue represent a new synthesis of ecology and endocrinology as discussed in three E-BIRD workshops. The three main foci are trade-offs and constraints, maternal effects and individual variation. Authors within each group present ecological and endocrinological aspects of their topics and many go on to outline testable hypotheses. Finally, we discuss where the major problems remain and how this issue points out where these need collaborative efforts of ecologists and endocrinologists. Specific challenges are raised to future researchers to break through intellectual barriers and explore new frontiers. This framework of topics will ultimately apply to all taxa because the principles involved are universal and hopefully will have direct application to programmes integrating organisms and genes throughout biological sciences. DOI

81. Gorman, KB; Flint, PL; Esler, D; Williams, TD. (2007) Ovarian follicle dynamics of female Greater Scaup during egg production. Journal of Field Ornithology 78: 64-73

80. Morgan, T.C., C.A. Bishop and T.D. Williams. (2007) Yellow-breasted Chat and Gray Catbird productivity in a fragmented western riparian system. Wilson Journal of Ornithology. Wilson Journal of Ornithology 119: 494-498.

79. Rowland, E; Love, OP; Verspoor, JJ; Sheldon, L; Williams, TD. (2007) Manipulating rearing conditions reveals developmental sensitivity in the smaller sex of a passerine bird, the European starling Sturnus vulgaris. Journal of Avian Biology 38: 612-618 Manipulating rearing conditions reveals developmental sensitivity in the smaller sex of a passerine bird, the European starling Sturnus vulgaris Traditionally, studies of sexually size-dimorphic birds and mammals report that the larger sex is more sensitive to adverse environmental conditions during ontogeny. However, recent studies in avian species that exhibit moderate size-dimorphism indicate that the smaller sex may be more sensitive to poor rearing conditions. To better understand sex-specific sensitivity in a passerine exhibiting moderate size-dimorphism, we examined growth, cell-mediated immunity (CMI) and survival of European starling Sturnus vulgaris nestlings following an experimental reduction of maternal rearing ability (via a feather-clipping manipulation). Contrary to conventional theory, daughters showed reduced growth in both body mass and measures of structural size in response to the maternal treatment. In contrast, sons showed no reductions in any of these traits in relation to the treatment. No sex-specific differences in nestling CMI were found for either group, although CMI of nestlings raised by manipulated mothers were higher than those of control nestlings. Finally, fledging sex ratios did not change from those at hatching indicating that neither sex appeared differentially sensitive to the maternal treatment in terms of mortality. These results reveal that variation in the quality of the rearing environment can have significant effects on the smaller sex of a passerine exhibiting moderate dimorphism and as such support recent studies of species with small-moderate sexual size-dimorphism. Combined results suggest that sex-specific effects of environmental variation on nestling development may be both context- (i.e., brood size, resource level, hatching order) and temporally- (when during development they occur) specific. Furthermore, more studies are needed that examine multiple traits at several developmental stages and then follow the sexes over the longer-term to examine potential effects on fitness. DOI

78. Salvante, KG; Lin, G; Walzem, RL; Williams, TD. (2007) Characterization of very-low density lipoprotein particle diameter dynamics in relation to egg production in a passerine bird. Journal of Experimental Biology 210: 1064-1074 Characterization of very-low density lipoprotein particle diameter dynamics in relation to egg production in a passerine bird VLDL; yolk-targeted VLDL; reproduction; VLDL particle diameter; zebra finch During avian egg production, oestrogen mediates marked increases in hepatic lipid production and changes in the diameter of assembled very-low density lipoprotein (VLDL). A nearly complete shift from generic VLDL (similar to 70 nm in diameter), which transports lipids to peripheral tissues, to yolk-targeted VLDL (VLDLy) (similar to 30 nm), which supplies the yolk with energy-rich lipid, has been observed in the plasma of laying domestic fowl. We validated an established dynamic laser scattering technique for a passerine songbird Taeniopygia guttata, the zebra finch, to characterize the dynamics of VLDL particle diameter distribution in relation to egg production. We predicted that non-gallinaceous avian species that have not been selected for maximum egg production would exhibit less dramatic shifts in lipid metabolism during egg production. As predicted, there was considerable overlap between the VLDL particle diameter distributions of laying and nonlaying zebra finches. But unexpectedly, non-laying zebra finches had VLDL diameter distributions that peaked at small particles and had relatively few large VLDL particles. As a result, laying zebra finches, in comparison, had diameter distributions that were shifted towards larger VLDL particles. Nevertheless, laying zebra finches, like laying chickens, had larger proportions of particles within proposed VLDLy particle diameter ranges than non-laying zebra finches (e.g. sVLDLy: 50% vs 37%). Furthermore, zebra finches and chickens had similar modal (29.7 nm in both species) and median (32.7 nm vs 29.6 nm) VLDL particle diameters during egg production. Therefore, although zebra finches and chickens exhibited opposing directional shifts in VLDL particle diameter distribution during egg production, the modifications to VLDL particle structure in both species resulted in the realization of a common goal, i.e. to produce and maintain a large proportion of small VLDL particles of specific diameters that are capable of being incorporated into newly forming egg yolks. DOI

77. Salvante, KG; Walzem, RL; Williams, TD. (2007) What comes first, the zebra finch or the egg: temperature-dependent reproductive, physiological and behavioural plasticity in egg-laying zebra finches. Journal of Experimental Biology 210: 1325-1334 What comes first, the zebra finch or the egg: temperature-dependent reproductive, physiological and behavioural plasticity in egg-laying zebra finches temperature; egg production; lipid allocation; very low density lipoprotein (VLDL); food intake; zebrafinch; chicken Avian reproduction is generally timed to synchronize chick-rearing with periods of increased food abundance. Consequently, the energetically demanding period of egg production may coincide with periods of lower food availability, fluctuating temperature and more unstable weather. Little is known about the physiological mechanisms underlying temperature-induced variation in egg production. We therefore examined the influence of low ambient temperature (7 degrees C vs 21 degrees C) on reproductive output (e.g. egg mass, clutch size, laying interval, laying rate), daily food consumption and lipid variables in zebra finches Taeniopygia guttata. When faced with egg production at 7 degrees C, laying zebra finches increased energy intake by 12.67 kJ day(-1), and were thus able to maintain body condition (e.g. body mass, fat and muscle score) and circulating triacylglyceride at levels comparable to those at 21 degrees C. However, when producing eggs at 7 degrees C, females took longer to initiate egg laying (6.5 vs 6.1 days at 21 degrees C), and ultimately laid fewer eggs (5.5 vs 6.0 eggs) at a slower rate (0.90 eggs day(-1) vs 0.95 eggs day(-1)). These temperature-related declines in reproductive output were accompanied by decreases in modal (from 36.6 at 21 degrees C to 24.3 nm at 7 degrees C) and median very low density lipoprotein (VLDL) particle diameter (from 29.6 to 26.4 nm) and in the proportion of VLDL particles that were capable of passing through the pores in the ovary to access the developing ovarian follicles (i.e. particles with diameters between 25 and 44 nm; from 45.90% to 32.55%). However, variation in reproductive output was not related to any static concentration or structural measure of VLDL. Therefore, other temperature-dependent mechanisms must be involved in the physiological processes that regulate reproductive output of passerine birds at low ambient temperatures. DOI

76. Verspoor, JJ; Love, OP; Rowland, E; Chin, EH; Williams, TD. (2007) Sex-specific development of avian flight performance under experimentally altered rearing conditions. Behavioral Ecology 18: 967-973 DOI

75. Wagner, EC; Williams, TD. (2007) Experimental (antiestrogen-mediated) reduction in egg size negatively affects offspring growth and survival. Physiological and Biochemical Zoology 80: 293-305

74. Williams, TD; Warnock, N; Takekawa, JY; Bishop, MA. (2007) Flyway-scale variation in plasma triglyceride levels as an index of refueling rate in spring-migrating Western Sandpipers (Calidris mauri). Auk 124: 886-897

73. Zera, A.J., L.G. Harshman and T.D. Williams. (2007) Evolutionary endocrinology: the developing synthesis between endocrinology and evolutionary genetics. Annual Review of Ecology Evolution and Systematics

72. McKinney, MA; Cesh, LS; Elliott, JE; Williams, TD; Garcelon, DK; Letcher, RJ. (2006) Brominated flame retardants and halogenated phenolic compounds in North American west coast bald eaglet (Haliaeetus leucocephalus) plasma. Environ Sci Technol 40: 6275-6281

71. Seaman, DAA; Guglielmo, CG; Elner, RW; Williams, TD. (2006) Landscape-scale physiology: Site differences in refueling rates indicated by plasma metabolite analysis in free-living migratory sandpipers. Auk 123: 563-574

70. Stein, RW; Williams, TD. (2006) Causes and consequences of post-growth age-dependent differences in small intestine size in a migratory sandpiper (Calidris mauri, Western Sandpiper). Funct Ecol 20: 142-150

69. Vezina, F; Speakman, JR; Williams, TD. (2006) Individually variable energy management strategies in relation to energetic costs of egg production. Ecology 87: 2447-2458 Individually variable energy management strategies in relation to energetic costs of egg production basal metabolic rate (BMR); daily energy expenditure (DEE); egg production costs; energy reallocation; reproduction; resting metabolic rate (RMR); Taeniopygia guttata; Zebra Finch Marked interindividual variation in metabolic rate suggests considerable complexity in energy management strategies, but attempts to further our understanding of the relationship between resting metabolic rate (RMR), daily energy expenditure (DEE), and reproductive effort have been hampered by the complexity of studying this system in the field. Here, we describe energy management strategies in a captive-breeding system, using Zebra Finches (Taeniopygia guttata), to demonstrate the high-level of complexity and interindividual variability in energy expenditure, food intake, locomotor activity, and reproductive effort. In particular, we investigated whether the increase in RMR associated with egg production is additive, resulting in higher DEE and a need for elevated food intake, or whether this cost is compensated by reduced expenditure in nonreproductive components of the energy budget. We found high levels of intra-individual variation in energy expenditure associated with egg production in female Zebra Finches, e.g., comparing nonbreeding stage with the one-egg stage, change in RMR varied from 4.0% and 41.3%, and change in DEE varied from -33.3% to +46.4%. This variation was systematically related to aspects of locomotor activity and reproductive effort. Females with the largest increase in RMR during egg production decreased locomotor activity the most but still had increased DEE at the one-egg stage, and females with high DEE at the one-egg stage produced larger clutches. Our study suggests that females minimize increases in DEE during egg production through behavioral energy reallocation (reduced locomotor activity) but that individuals differ in their use of this strategy, which, in turn, is related to the absolute level of reproductive investment. This suggests a very complex, individually variable system of energy management to meet the demands of egg production.

68. Warnock, N; Bishop, MA; Takekawa, J; Williams, TD. (2006) Connecting the spots - Influences on site use by migratory Pacific Flyway shorebirds. J Ornithol 147: 53-53

67. Chin, EH; Love, OP; Clark, AM; Williams, TD. (2005) Brood size and environmental conditions sex-specifically affect nestling immune response in the European starling Sturnus vulgaris. J Avian Biol 36: 549-554

66. Dods, PL; Birmingham, EM; Williams, TD; Ikonomou, MG; Bennie, DT; Elliott, JE. (2005) Reproductive success and contaminants in tree swallows (Tachycineta bicolor) breeding at a wastewater treatment plant. Environmental Toxicology and Chemistry 24: 3106-3112

65. Gill, H; Williams, TD; Bishop, CA; Cheng, KM; Elliott, JE. (2005) Effects of azinphos-methyl on cholinergic responses and general health in zebra finches (Taeniopygia guttata) after previous treatment with p,p '-DDE. Archives of Environmental Contamination and Toxicology 48: 118-126

64. Gorman, KB; Williams, TD. (2005) Correlated evolution of maternally derived yolk testosterone and early developmental traits in passerine birds. Biology Letters 1: 461-464

63. Gurney, KE; Williams, TD; Smits, JE; Wayland, M; Trudeau, S; Bendell-Young, LI. (2005) Impact of oil-sands based wetlands on the growth of mallard (Anas platyrhynchos) ducklings. Environmental Toxicology and Chemistry 24: 457-463

62. Love, OP; Chin, EH; Wynne-Edwards, KE; Williams, TD. (2005) Stress hormones: A link between maternal condition and sex-biased reproductive investment. American Naturalist 166: 751-766 Stress hormones: A link between maternal condition and sex-biased reproductive investment corticosterone; sex ratio theory; sex allocation theory; maternal condition; maternal effects; yolk hormones In species where offspring fitness is sex-specifically influenced by maternal reproductive condition, sex allocation theory predicts that poor-quality mothers should invest in the evolutionarily less expensive sex. Despite an accumulation of evidence that mothers can sex-specifically modulate investment in offspring in relation to maternal quality, few mechanisms have been proposed as to how this is achieved. We explored a hormonal mechanism for sex-biased maternal investment by measuring and experimentally manipulating baseline levels of the stress hormone corticosterone in laying wild female European starlings (Sturnus vulgaris) and examining effects on sex ratio and sex-specific offspring phenotype adjustment. Here we show that baseline plasma corticosterone is negatively correlated with energetic body condition in laying starlings, and subsequent experimental elevation of maternal baseline plasma corticosterone increased yolk corticosterone without altering maternal condition or egg quality per se. Hormonal elevation resulted in the following: female-biased hatching sex ratios (caused by elevated male embryonic mortality), lighter male offspring at hatching (which subsequently grew more slowly during postnatal development), and lower cell-mediated immune (phytohemagglutinin) responses in males compared with control-born males; female offspring were unaffected by the manipulation in both years of the study. Elevated maternal corticosterone therefore resulted in a sex-biased adjustment of offspring quality favorable to female offspring via both a sex ratio bias and a modulation of male phenotype at hatching. In birds, deposition of yolk corticosterone may benefit mothers by acting as a bet-hedging strategy in stochastic environments where the correlation between environmental cues at laying (and therefore potentially maternal condition) and conditions during chick-rearing might be low and unpredictable. Together with recent studies in other vertebrate taxa, these results suggest that maternal stress hormones provide a mechanistic link between maternal quality and sex-biased maternal investment in offspring.

61. Seaman, DA; Guglielm, CG; Williams, TD. (2005) Effects of physiological state, mass change and diet on plasma metabolite profiles in the western sandpiper Calidris mauri. Journal of Experimental Biology 208: 761-769

60. Stein, RW; Place, AR; Lacourse, T; Guglielmo, CG; Williams, TD. (2005) Digestive organ sizes and enzyme activities of refueling western sandpipers (Calidris mauri): Contrasting effects of season and age. Physiological and Biochemical Zoology 78: 434-446

59. Vezina, F; Williams, TD. (2005) The metabolic cost of egg production is repeatable. Journal of Experimental Biology 208: 2533-2538

58. Vezina, F; Williams, TD. (2005) Interaction between organ mass and citrate synthase activity as an indicator of tissue maximal oxidative capacity in breeding European Starlings: implications for metabolic rate and organ mass relationships. Functional Ecology 19: 119-128

57. Williams, TD. (2005) Mechanisms underlying the costs of egg production. Bioscience 55: 39-48

56. Williams, TD; Ames, CE; Kiparissis, Y; Wynne-Edwards, KE. (2005) Laying-sequence-specific variation in yolk oestrogen levels, and relationship to plasma oestrogen in female zebra finches (Taeniopygia guttata). Proceedings of the Royal Society B-Biological Sciences 272: 173-177

55. Love, OP; Breuner, CW; Vezina, F; Williams, TD. (2004) Mediation of a corticosterone-induced reproductive conflict. Hormones and Behavior 46: 59-65

54. Peery, AZ; Beissinger, SR; Newman, SH; Becker, BH; Burkett, E; Williams, TD. (2004) Individual and temporal variation in inland flight behavior of Marbled Murrelets: Implications for population monitoring. Condor 106: 344-353

53. Peery, MZ; Beissinger, SR; Newman, SH; Burkett, EB; Williams, TD. (2004) Applying the declining population paradigm: Diagnosing causes of poor reproduction in the marbled murrelet. Conservation Biology 18: 1088-1098

52. Sockman, KW; Williams, TD; Dawson, A; Ball, GF. (2004) Prior experience with photostimulation enhances photo-induced reproductive development in female European starlings: A possible basis for the age-related increase in avian reproductive performance. Biology of Reproduction 71: 979-986

51. Williams, TD; Ames, CE. (2004) Top-down regression of the avian oviduct during late oviposition in a small passerine bird. Journal of Experimental Biology 207: 263-268

50. Williams, TD; Challenger, WO; Christians, JK; Evanson, M; Love, O; Vezina, F. (2004) What causes the decrease in haematocrit during egg production? Functional Ecology 18: 330-336

49. Williams, TD; Kitaysky, AS; Vezina, F. (2004) Individual variation in plasma estradiol-17 beta and androgen levels during egg formation in the European starling Sturnus vulgaris: implications for regulation of yolk steroids. General and Comparative Endocrinology 136: 346-352 Individual variation in plasma estradiol-17 beta and androgen levels during egg formation in the European starling Sturnus vulgaris: implications for regulation of yolk steroids Sturnus vulgaris; estradiol-17 beta; androgens; egg formation; maternal effects While it is clear that maternal transfer of steroids to egg yolk can have significant effects on offspring phenotype, an unresolved question is whether females can facultatively adjust yolk hormone levels independently of their own plasma levels or whether yolk steroid levels are simply a direct consequence of temporal variation in the female's hormonal status. In part, this is because we lack detailed information about the day-to-day pattern of changes in plasma hormone levels during the laying cycle for non-domesticated birds. Here, we describe changes in plasma estradiol-17beta (E2) and androgens, throughout laying in relation to specific stages of ovarian follicular development in the European starling (Sturnus vulgaris). Plasma E2 levels increased rapidly from the onset of rapid yolk development (RYD) to reach maximum levels in birds with a complete follicle hierarchy ( greater than or equal to 4 yolky follicles). However, levels decreased linearly throughout the later stages of follicle development returning to pre-breeding values before the final yolky follicle was ovulated. In females with greater than or equal to 4 yolky follicles there was 10-fold variation in plasma E2 levels among individual females, but this was not related to plasma levels of the main yolk precursor vitellogenin or to the total mass of yolky follicles developing at the time of blood sampling. In contrast to E2, plasma androgen levels showed only a very gradual linear decline throughout the laying cycle from pre-RYD to clutch completion. Furthermore, androgen levels showed less individual variability: 4-fold variation among females with greater than or equal to 4 yolky follicles, although this was also independent of our measures of reproductive function. Data on inter- and intra-individual variation in female hormone levels are important to set-up a priori predictions for, and interpretation of, studies of yolk hormone levels. (C) 2004 Elsevier Inc. All rights reserved.

48. Egeler, O; Seaman, D; Williams, TD. (2003) Influence of diet on fatty-acid composition of depot fat in Western sandpipers (Calidris mauri). Auk 120: 337-345

47. Guglielmo, CG; Williams, TD. (2003) Phenotypic flexibility of body composition in relation to migratory state, age, and sex in the western sandpiper (Calidris mauri). Physiological and Biochemical Zoology 76: 84-98

46. Salvante, KG; Williams, TD. (2003) Effects of corticosterone on the proportion of breeding females, reproductive output and yolk precursor levels. General and Comparative Endocrinology 130: 205-214

45. Stein, RW; Williams, TD. (2003) Tissue damage precludes the use of the everted sleeve technique to measure nutrient uptake in a small migratory shorebird, the western sandpiper (Calidris mauri). Physiological and Biochemical Zoology 76: 762-770

44. Tranquilla, LAM; Bradley, RW; Lank, DB; Williams, TD; Lougheed, LW; Cooke, F. (2003) The reliability of brood patches in assessing reproductive status in the Marbled Murrelet: Words of caution. Waterbirds 26: 108-118 The reliability of brood patches in assessing reproductive status in the Marbled Murrelet: Words of caution brood patch; reproductive status; incubation; Marbled Murrelet; Brachyramplens marmoratus; radio telemetry; vitellogenin; Marbled Murrelet; Marbled Murrelets; The assumption that brood patches identify incubating birds is a pervasive one in avian literature, and its a result, brood patches are often used to infer breeding status. Although the developmental stages of the brood patch with specific: reproductive stages in passerines have been described, this information for seabirds is not often reported. Thus, for birds whose breeding activities are not easily observed, it is difficult to confirm (1) that it is valid to assume that a bird which has some stage of brood patch is a nester or putative nester, and (2) whether specific stages of brood patch development reflect specific stages of the breeding cycle. We tested the utility oh brood patch scores to infer breeding status in a non-colonial seabird, the Marbled Murrelet (Brachyramphus marmoratus), a species always captured away from the nest site. We confirmed the breeding status of murrelets with brood patches, and assessed the specific stages of brood patch development to the timing of egg-production (using a physiological analysis) and the onset of incubation (rising radio telemetry). Murrelets with brood patches were not always nesters or putative nesters (58% of birds with brood patches were producing eggs, and 56% of radio-tagged birds with brood patches began incubation), and brood patch score did not predict which birds were more likely to become egg-producers or incubators. Specific brood patch stages did not always correlate with specific breeding stages (e.g., the brood patch of egg-producers ranged from absent to fully-developed). Birds with fully developed brood patches took from 3-30 days to start incubation. Brood patch development accurately depicted the average population incubation time, but we caution against rising brood patches to predict the timing of an individual breeding attempt, and suggest that when possible, researchers should try to confirm breeding activities using other methods.

43. Tranquilla, LAM; Yen, PPW; Bradley, RW; Vanderkist, BA; Lank, DB; Parker, NR; Drever, M; Lougheed, LW; Kaiser, GW; Williams, TD. (2003) Do two murrelets make a pair? Breeding status and behavior of marbled murrelet pairs captured at sea. Wilson Bulletin 115: 374-381

42. Tranquilla, LM; Williams, T; Cooke, F. (2003) Using vitellogenin to identify interannual variation in breeding chronology of marbled murrelets (Brachyramphus marmoratus). Auk 120: 512-521

41. Vezina, F; Salvante, KG; Williams, TD. (2003) The metabolic cost of avian egg formation: possible impact of yolk precursor production? Journal of Experimental Biology 206: 4443-4451

40. Vezina, F; Williams, TD. (2003) Plasticity in body composition in breeding birds: What drives the metabolic costs of egg production? Physiological and Biochemical Zoology 76: 716-730 Plasticity in body composition in breeding birds: What drives the metabolic costs of egg production? Body composition in vertebrates is known to show phenotypic plasticity, and changes in organ masses are usually rapid and reversible. One of the most rapid and reversible changes is the transformation of the female avian reproductive organs before breeding. This provides an excellent system to investigate the effects of plasticity in organ size on basal metabolic rate (BMR) through relationships between organ masses and BMR. We compared body composition of female European starlings (Sturnus vulgaris) during various reproductive stages over 3 yr and investigated the pattern of changes in reproductive and nonreproductive organ mass during follicular development and ovulation. Furthermore, we analyzed the relationship between organ mass and resting metabolic rate (RMR) in nonbreeding, laying, and chick-rearing females. Our analysis revealed marked variation in organ masses between breeding stages but no consistent pattern among years except for kidney and pectoralis muscle. Furthermore, changes in nonreproductive organs did not parallel the cycle of growth and regression of the reproductive organs. The oviduct gained 62% of its 22-fold increase in mass in only 3 d, and oviduct regression was just as rapid and began even before the final egg of the clutch was laid, with 42% of the oviduct mass lost before laying of the final egg. In laying females, 18% of variation in mass-corrected RMR was explained by the mass of the oviduct (r(2) = 0.18, n = 80, P < 0.0005), while pectoralis muscle mass in nonbreeding individuals and liver and gizzard mass in chick-rearing females were the only organs significantly related to RMR (r(2) = 0.31-0.44). We suggest that the nonreproductive organs are affected more by changes in local ecological conditions than the reproductive state itself and that the activity and maintenance cost of the oviduct is high enough that selection has led to a very tight size-function relationship for this organ.

39. Williams, TD; Christians, JK. (2003) Experimental dissociation of the effects of diet, age and breeding experience on primary reproductive effort in zebra finches Taeniopygia guttata. Journal of Avian Biology 34: 379-386

38. Williams, TD; Miller, M. (2003) Individual and resource-dependent variation in ability to lay supranormal clutches in response to egg removal. Auk 120: 481-489 Individual and resource-dependent variation in ability to lay supranormal clutches in response to egg removal We investigated individual and resource-dependent variation in ability of female Zebra Finches (Taeniopygia guttata) to lay supranormal clutches in response to egg removal, and effect of continuous laying on (1) egg composition and (2) plasma yolk precursor levels. Egg removal significantly increased the number of eggs that individual females laid, but that response was diet-dependent: on a high-quality (egg-supplemented) diet, females laid 12.4 +/- 1.0 more eggs compared with their pretreatment clutch size; whereas on the low-quality (seed-only) diet, females laid only 4.9 +/- 1.2 more eggs. Removal clutch size (i.e. total number of eggs laid in response to egg removal) was positively correlated with pretreatment mean egg mass and clutch size on the low-quality diet, but not on the high-quality diet. That suggests that there is interindividual variation in egg-laying ability ("large-egg" females had a greater capacity to respond to egg removal than "small-egg" females), but that higher resource levels can overcome individual differences. Egg mass did not vary with laying sequence in supranormal clutches (up to 22 eggs); however, there was a significant decrease (6%) in yolk protein content of additional eggs that was apparent by the tenth egg laid (i.e. only 4-5 more than the normal clutch size). Plasma levels of the two yolk precursors, vitellogenin and very-low-density lipoprotein (VLDL), were independent of diet and did not differ in individual birds at the 1 egg stage versus the 14 egg stage. However, there was a systematic change in relationship between yolk lipid content and plasma VLDL levels, from nonsignificant for third-laid eggs to significant and positive for sixteenth-laid eggs. We propose a possible mechanism linking female condition and egg-laying ability: good quality females, capable of laying extended clutches, are able to maintain production of generic VLDL for their own metabolic needs, as well as producing yolk-targeted VLDL, whereas poor quality females are not.

37. Christians, JK; Williams, TD. (2002) Effects of porcine follicle-stimulating hormone on the reproductive performance of female zebra finches (Taeniopygia guttata). General and Comparative Endocrinology 125: 121-131

36. Guglielmo, CG; Haunerland, NH; Hochachka, PW; Williams, TD. (2002) Seasonal dynamics of flight muscle fatty acid binding protein and catabolic enzymes in a migratory shorebird. American Journal of Physiology-Regulatory Integrative and Comparative Physiology 282: R1405-R1413

35. Guglielmo, CG; O'Hara, PD; Williams, TD. (2002) Extrinsic and intrinsic sources of variation in plasma lipid metabolites of free-living western sandpipers (Calidris mauri). Auk 119: 437-445

34. Guglielmo, CG; Williams, TD; Zwingelstein, G; Brichon, G; Weber, JM. (2002) Plasma and muscle phospholipids are involved in the metabolic response to long-distance migration in a shorebird. Journal of Comparative Physiology B-Biochemical Systemic and Environmental Physiology 172: 409-417

33. McFarland, CN; Bendell-Young, LI; Guglielmo, C; Williams, TD. (2002) Kidney, liver and bone cadmium content in the western sandpiper in relation to migration. Journal of Environmental Monitoring 4: 791-795

32. Salvante, KG; Williams, TD. (2002) Vitellogenin dynamics during egg-laying: daily variation, repeatability and relationship with egg size. Journal of Avian Biology 33: 391-398

31. Vezina, F; Williams, TD. (2002) Metabolic costs of egg production in the European starling (Sturnus vulgaris). Physiological and Biochemical Zoology 75: 377-385

30. Challenger, WO; Williams, TD; Christians, JK; Vezina, F. (2001) Follicular development and plasma yolk precursor dynamics through the laying cycle in the European starling (Sturnus vulgaris). Physiological and Biochemical Zoology 74: 356-365 Follicular development and plasma yolk precursor dynamics through the laying cycle in the European starling (Sturnus vulgaris) We investigated the quantitative matching of plasma yolk precursor supply (the plasma pool) to follicle demand during yolk formation in European starlings (Sturnus vulgaris). Plasma concentrations of the two yolk precursors, vitellogenin (VTG) and very low density lipoprotein (VLDL), were only elevated coincident with rapid yolk development (RYD) and matched variation in total yolky follicle mass. VTG and VLDL were low (<0.4 <mu>g/mL and <4.2 mg/mL, respectively) in nonbreeders and prebreeders with no yolky follicles, and at clutch completion. They increased to 4.02 <mu>g/mL and 19.4 mg/mL in birds with a full follicle hierarchy (F-1-F-4), and concentrations then remained high and actually increased up to the point where only a single, yolky (F-1) follicle remained. However, there was some evidence for mismatching of supply and demand: (a) precursor concentrations increased throughout the laying cycle even though the number of developing follicles decreased. We suggest that this is because of a requirement to maintain a large precursor pool to maintain high uptake rates; and (b) in birds with a full follicle hierarchy, precursor concentrations were negatively correlated with total follicle mass. This suggests that high uptake rates in large follicles can actually deplete circulating precursor concentrations. Plasma concentrations of both yolk precursors increased rapidly in the early morning with (predicted) time after ovulation, consistent with a lack of fine control of precursor concentrations. However, mean plasma VTG concentrations did not differ between morning or evening samples. In contrast, plasma VLDL concentrations were lower in the morning (16.8 mg/mL) than in the evening (22.9 mg/mL). Although there is marked individual variation in plasma VTG and VLDL (four- to eightfold), both precursors were repeatable in the short term (24 h), and plasma VTG was repeatable over a 14-d interval between successive breeding attempts.

29. Christians, JK; Williams, TD. (2001) Interindividual variation in yolk mass and the rate of growth of ovarian follicles in the zebra finch (Taeniopygia guttata). Journal of Comparative Physiology B-Biochemical Systemic and Environmental Physiology 171: 255-261

28. Christians, JK; Williams, TD. (2001) Intraspecific variation in reproductive physiology and egg quality in the European Starling Sturnus vulgaris. Journal of Avian Biology 32: 31-37

27. Clair, CCS; Clair, RCS; Williams, TD. (2001) Does kleptoparasitism by glaucous-winged gulls limit the reproductive success of Tufted Puffins? Auk 118: 934-943

26. Guglielmo, C; Piersma, T; Williams, TD. (2001) A sport-physiological perspective on bird migration: Evidence for flight-induced muscle damage. Journal of Experimental Biology 204: 2683-2690

25. Shepherd, PCF; Lank, DB; Smith, BD; Warnock, N; Kaiser, GW; Williams, TD. (2001) Sex ratios of Dunlin wintering at two latitudes on the Pacific coast. Condor 103: 352-360

24. Williams, TD. (2001) Experimental manipulation of female reproduction reveals an intraspecific egg size-clutch size trade-off. Proceedings of the Royal Society of London Series B-Biological Sciences 268: 423-428

23. Egeler, O; Williams, TD. (2000) Seasonal, age, and sex-related variation in fatty-acid composition of depot fat in relation to migration in Western Sandpipers. Auk 117: 110-119 Seasonal, age, and sex-related variation in fatty-acid composition of depot fat in relation to migration in Western Sandpipers The composition of depot fat in Western Sandpipers (Calidris mauri) was dominated by C-16 and C-18 fatty acids (palmitate, 16:0; palmitoleate, 16:1; stearate, 18:0; oleate, 18:1), which together comprised 80 to 90% of all fatty acids analyzed. Significant seasonal variation occurred in the relative proportion of specific fatty acids and the ratio of saturated to unsaturated fatty acids in relation to the migratory cycle of the sandpipers. In adults of both sexes, the proportion of 16:0 and 18:0 fatty acids decreased from winter (December) to premigration (March) to spring migration (May), whereas the proportion of 16:1 and 18:1 fatty acids increased over these same periods. Consequently, total unsaturated fatty acids increased by 34% between the winter and premigratory phase, and by a further 22% between premigration and spring migration. Therefore, biochemical modification of adipose tissue in Western Sandpipers begins during the premigratory period in preparation for long-distance flight but continues as migration progresses, perhaps reflecting a training component of physiological modulation for migration. Juveniles showed similar changes to adults in the composition of their depot fat during the "premigratory" period, even though most juveniles do not undergo hyperphagia or rapid fattening at this wintering site. Potential prey species collected from a wintering site in Panama had a higher proportion of saturated fatty acids, less 16:1 and 18:1, and more 18:0 fatty acid compared with those from a migratory stopover site in British Columbia, paralleling the seasonal changes in depot fatty-acid composition observed in Western Sandpipers. However, the fact that Western Sandpipers show an increase in level of unsaturation and in the amounts of 16:1 and 18:1 fatty acids in their fat stores on the wintering ground prior to migration suggests that seasonal variation in fatty-acid composition is not entirely diet dependent.

22. Egeler, O; Williams, TD; Guglielmo, CG. (2000) Modulation of lipogenic enzymes, fatty acid synthase and Delta(9)-desaturase, in relation to migration in the western sandpiper (Calidris mauri). Journal of Comparative Physiology B-Biochemical Systemic and Environmental Physiology 170: 169-174

21. Moore, DJ; Williams, TD; Morris, RD. (2000) Mate provisioning, nutritional requirements for egg production, and primary reproductive effort of female Common Terns Sterna hirundo. Journal of Avian Biology 31: 183-196 Mate provisioning, nutritional requirements for egg production, and primary reproductive effort of female Common Terns Sterna hirundo We assessed the nutritional importance of male provisioning to females during egg production and its effects on clutch parameters (egg size, length of the laying period) in Common Terns Sterna hirundo: (1) we estimated the costs of egg production by modeling the daily protein, lipid, and energy requirements of laying females, and (2) compared these costs to both the amount, and the timing, of the male's contribution via mate provisioning. Net lipid, net protein, and gross energy requirements for a three-egg clutch were estimated to be 5.4 g, 8.6 g, and 569 kJ respectively. Peak protein and lipid requirements occurred one (day - 1) and two (day - 2) days before laying, respectively. peal; energy requirement occurred on day - 1; a cost of 127% to 157% above maintenance. Variation in male provisioning effort (in terms of energy and nutrients delivered) paralleled variation in predicted female requirements For egg production at the level of individual pairs. Males delivered protein in excess of the female's requirements on all days investigated. Male lipid delivery accounted for 45% of female net requirement on the day when demand was greatest (day - 2), but exceeded requirements on all other days. However, the proportion of the female's total energy budget (egg production, maintenance, and activity costs) that was supplied by her mate rose from an average of 29% on day - 2 to 76% during the interval between second and third eggs. Paradoxically, females that were fed at higher rates during the interval between first and second eggs produced clutches with lower total volumes, smaller last-laid eggs, and clutches with a greater egg-size hierarchy than conspecifics receiving less food from their mates. Also, females fed at higher rates during the interval between second and third eggs took longer to produce their clutch. These negative relationships between mate provisioning and clutch parameters contrast with previous studies in this and other species.

20. Vanderkist, BA; Williams, TD; Bertram, DF; Lougheed, LW; Ryder, JL. (2000) Indirect, physiological assessment of reproductive state and breeding chronology in free-living birds: an example in the Marbled Murrelet (Brachyramphus marmoratus). Functional Ecology 14: 758-765

19. Williams, TD. (2000) Experimental (Tamoxifen-Induced) manipulation of female reproduction in zebra finches (Taeniopygia guttata). Physiological and Biochemical Zoology 73: 566-573

18. Williams, TD; Martyniuk, CJ. (2000) Tissue mass dynamics during egg-production in female Zebra Finches Taeniopygia guttata: dietary and hormonal manipulations. Journal of Avian Biology 31: 87-95

17. Butler, RW; Williams, TD; Bishop, MA; Warncock, N. (1999) Gone with the wind? Reply. Auk 116: 563-564

16. Christians, JK; Williams, TD. (1999) Organ mass dynamics in relation to yolk precursor production and egg formation in European starlings Sturnus vulgaris. Physiological and Biochemical Zoology 72: 455-461

15. Christians, JK; Williams, TD. (1999) Effects of exogenous 17 beta-estradiol on tee reproductive physiology and reproductive performance of European starlings (Sturnus vulgaris). Journal of Experimental Biology 202: 2679-2685

14. Smits, JE; Williams, TD. (1999) Validation of immunotoxicology techniques in passerine chicks exposed to oil sands tailings water. Ecotoxicology and Environmental Safety 44: 105-112

13. Vanderkist, BA; Xue, XH; Griffiths, R; Martin, K; Beauchamp, W; Williams, TD. (1999) Evidence of in male-bias in capture samples of Marbled Murrelets from genetic studies in British Columbia. Condor 101: 398-402

12. Williams, TD. (1999) Parental and first generation effects of exogenous 17 beta-estradiol on reproductive performance of female zebra finches (Taeniopygia guttata). Hormones and Behavior 35: 135-143 Parental and first generation effects of exogenous 17 beta-estradiol on reproductive performance of female zebra finches (Taeniopygia guttata) 17 beta-estradiol; female reproductive effort; intergenerational effects Steroids hormones have numerous "activational" effects in adult birds, regulating sexual behavior, and more recently maternal androgens have been shown to have potentially important "organizational" effects in ovo, influencing offspring growth, development, and behavior. In this study I investigated parental and first-generation effects of exogenous estrogens on female reproduction in zebra finches (Taeniopygia guttata). 17 beta-Estradiol (E-2; 1.2 mu g/g, 4 daily injections i.m.) elevated plasma levels of the yolk precursors, vitellogenin (VTG) and very low-density lipoprotein (VLDL), in nonbreeding females to levels similar to those of breeding females. However, E-2-treatment of breeding females caused no significant change in plasma VTG or VLDL levels compared to control birds (measured at the 1-egg stage), and there was no difference in reproductive performance between groups (egg size, clutch size, timing of laying). E-2-treated females produced significantly more daughters than sons (21F:8M) at fledging, compared to control females (18F:19M). Nestling mortality was significantly higher in broods of E-2-treated females, suggesting that the skewed sex ratio may have resulted from differential mortality of male chicks. The pattern of chick mortality in E-2-broods was not consistent with this being caused by estrogen-mediated changes in parental behavior (e.g., provisoning). Mean egg mass of daughters of E-2-treated females was typical of experienced, adult breeders, and larger than normal, first-time breeders or control offspring (0.947 vs 0.850 g). There was no treatment effect on offspring clutch size or laying interval. These results suggest that early exposure to maternal estrogens in ovo might be involved in establishing intraindividual variation in female-specific phenotypic traits, as has previously been demonstrated for androgens and mate behavioral traits (e.g., aggression). (C) 1999 Academic Press.

11. Williams, TD; Christians, JK; Aiken, JJ; Evanson, M. (1999) Enhanced immune function does not depress reproductive output. Proceedings of the Royal Society of London Series B-Biological Sciences 266: 753-757

10. Williams, TD; Guglielmo, CG; Egeler, O; Martyniuk, CJ. (1999) Plasma lipid metabolites provide information on mass change over several days in captive western sandpipers. Auk 116: 994-1000

9. Williams, TD; Ternan, SP. (1999) Food intake, locomotor activity, and egg laying in zebra finches: Contributions to reproductive energy demand? Physiological and Biochemical Zoology 72: 19-27

8. Balzer, AL; Williams, TD. (1998) Do female zebra finches vary primary reproductive effort in relation to mate attractiveness? Behaviour 135: 297-309

7. Guglielmo, CG; Haunerland, NH; Williams, TD. (1998) Fatty acid binding protein, a major protein in the flight muscle of migrating Western Sandpipers. Comparative Biochemistry and Physiology B-Biochemistry & Molecular Biology 119: 549-555

6. Butler, RW; Williams, TD; Warnock, N; Bishop, MA. (1997) Wind assistance: A requirement for migration of shorebirds? Auk 114: 456-466 Wind assistance: A requirement for migration of shorebirds? We investigated the importance of wind-assisted night for northward (spring) migration by Western Sandpipers (Calidris mauri) along the Pacific Coast of North America. Using current models of energy costs of flight and recent data on the phenology of migration, we estimated the energy (fat) requirements for migration in calm winds and with wind-assisted flight for different rates of fat deposition: (1) a variable rate, assuming that birds deposit the minimum amount of fat required to reach the next stopover site; (2) a constant maximum rate of 1.0 g/day; and (3) a lower constant rate of 0.4 g/day. We tested these models by comparing conservative estimates of predicted body mass along the migration route with empirical data on body mass of Western Sandpipers at different stopover sites and upon arrival at the breeding grounds. In calm conditions, birds would have to deposit unrealistically high amounts of fat (up to 330% of observed values) to maintain body mass above absolute lean mass values. Fat-deposition rates of 1.0 g/day and 0.4 g/day, in calm conditions, resulted in a steady decline in body mass along the migration route with predicted body masses on arrival in Alaska of only 60% (13.6 g) and 26% (5.9 g) of average lean mass (22.7 g). Conversely, birds migrating with wind assistance would be able to complete migration with fat-deposition rates as low as 0.4 g/day, similar to values reported for this size bird from field studies. Our results extend the conclusion of the importance of winds for large, long-distance migrants to a small, short-distance migrant. We suggest that the migratory decisions of birds are more strongly influenced by the frequency and duration of winds aloft, i.e. by events during the flight phase, than by events during the stopover phase of migration, such as fat-deposition rate, that have been the focus of much recent migration theory. Received 3 September 1996, accepted 14 February 1997.

5. Williams, TD; Monaghan, P; Mitchell, PI; Scott, I; Houston, DG; Ramsey, S; Ensor, K. (1997) Evaluation of a non-destructive method for determining egg composition using total body electrical conductivity (TOBEC) measurements. Journal of Zoology 243: 611-622

4. Williams, TD. (1996) Variation in reproductive effort in female zebra finches (Taeniopygia guttata) in relation to nutrient-specific dietary supplements during egg laying. Physiological Zoology 69: 1255-1275

3. Williams, TD. (1996) Intra- and inter-individual variation in reproductive effort in captive breeding zebra finches (Taeniopygia guttata). Canadian Journal of Zoology-Revue Canadienne de Zoologie 74: 85-91

2. Williams, TD; Cooch, EG. (1996) Egg size, temperature and laying sequence: Why do Snow Geese lay big eggs when it's cold? Functional Ecology 10: 112-118 Egg size, temperature and laying sequence: Why do Snow Geese lay big eggs when it's cold? physiological trade-offs; rapid yolk development; reproduction; thermoregulation 1. Several studies of altricial passerines ('income breeders') have shown that females lay smaller eggs when they experience low temperatures during egg formation, This is usually explained in terms of a 'physiological trade-off': birds having to divert more of their finite resources to maintenance and away from reproduction in cold weather, although little is known about the proximate mechanism(s) underlying this phenomenon. 2. We investigated the relationship between egg size and ambient temperature during egg formation period in the Lesser Snow Goose (Anser caerulescens caerulescens), a precocial, 'capital-breeding' species, using 10 years of data derived from a long-term. population study of this species at La Perouse Bay, Man., Canada. 3. Egg size was negatively correlated with ambient temperature in the Snow Goose, i.e. females laid larger eggs when temperatures were lower during egg formation, contrasting markedly with the positive correlation reported in altricial, income-breeders. 4. The effect of temperature on egg size was most marked for last-laid eggs within a clutch (b = 0.675 g degrees C-1), and for temperatures during the last half of the rapid yolk development (RYD) period (rather than for the whole or the middle of the RYD period), as predicted by an exponential growth curve for yolk development. 5. The relationship between egg mass and temperature was time- and laying-sequence specific: for first and middle eggs the correlation was positive early in the period of RYD and negative closer to ovulation. For last-laid eggs the correlation between egg mass and temperature was negative throughout the 10 day RYD period. 6. We suggest that the different relationship between egg size and temperature in the Snow Goose, compared to passerine species, may reflect different contributions of exogenous vs endogenous reserves, and different opportunities to increase energy availability through dietary intake. 7. Although statistically significant, temperature has only a small effect on egg size in the Lesser Snow Goose: the average range of temperatures encountered would only lead to a 3-5% difference in mean egg mass, This is consistent with high heritability of egg size.

1. Williams, TD; Jeffs, C; Murray, KA; Choudhury, S. (1996) Intraclutch egg-size variation in the barnacle goose Branta leucopsis: An egg-removal experiment. Ibis 138: 499-505

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