Digestive organ sizes and enzyme activities of refueling western sandpipers (Calidris mauri): Contrasting effects of season and age
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| Authors: | Stein, RW; Place, AR; Lacourse, T; Guglielmo, CG; Williams, TD |
| Year: | 2005 |
| Journal: | Physiological and Biochemical Zoology 78: 434-446 |
| Title: | Digestive organ sizes and enzyme activities of refueling western sandpipers (Calidris mauri): Contrasting effects of season and age |
| Abstract: | We examined seasonal and age-related variation in digestive organ sizes and enzyme activities in female western sandpipers (Calidris mauri) refueling at a coastal stopover site in southern British Columbia. Adult sandpipers exhibited seasonal variation in pancreatic and intestinal enzyme activities but not in digestive system or organ sizes. Spring migrants had 22% higher total and 67% higher standardized pancreatic lipase activities but 37% lower total pancreatic amylase activity than fall migrants, which suggests that the spring diet was enriched with lipids but low in glycogen. Spring migrants also had 47% higher total intestinal maltase activity as well as 56% higher standardized maltase and 13% higher standardized aminopeptidase-N activities. Spring migrants had higher total enzymic capacity than fall migrants, due primarily to higher total lipase and maltase activities. During fall migration, the juvenile's digestive system was 10% larger than the adult's, and it was composed differently: juveniles had a 16% larger small intestine but a 27% smaller proventriculus. The juvenile's larger digestive system was associated with lower total enzymic capacity than the adult's due to 20% lower total chitinase and 23% lower total lipase activities. These results suggest that juvenile western sandpipers may process food differently from adults and/or have a lower-quality diet. |
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