Mate provisioning, nutritional requirements for egg production, and primary reproductive effort of female Common Terns Sterna hirundo
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| Authors: | Moore, DJ; Williams, TD; Morris, RD |
| Year: | 2000 |
| Journal: | Journal of Avian Biology 31: 183-196 |
| Title: | Mate provisioning, nutritional requirements for egg production, and primary reproductive effort of female Common Terns Sterna hirundo |
| Abstract: | 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. |
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