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.
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada. rwstein@sfu.ca
authors.forename: R Will
authors.initials: RW
authors.lastname: Stein
authors.forename: Allen R
authors.initials: AR
authors.lastname: Place
authors.forename: Terri
authors.initials: T
authors.lastname: Lacourse
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Guglielmo
authors.forename: Tony D
authors.initials: TD
authors.lastname: Williams
mesh_terms: D000367:Age Factors; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D001646:Bile / Q000378:metabolism; D001955:British Columbia; D018826:CD13 Antigens / Q000378:metabolism; D046091:Charadriiformes / Q000033:anatomy & histology / Q000378:metabolism*; D002688:Chitinases / Q000378:metabolism; D004064:Digestive System / Q000033:anatomy & histology* / Q000201:enzymology*; D005243:Feces / Q000737:chemistry; D005260:Female; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000378:metabolism; D009929:Organ Size; D025341:Principal Component Analysis; D012621:Seasons; D014781:Viscera / Q000033:anatomy & histology*; D000520:alpha-Glucosidases / Q000378:metabolism
chemical_list: D008049:Lipase; D002688:Chitinases; D000520:alpha-Glucosidases; D018826:CD13 Antigens