Plasma metabolites and creatine kinase levels of shorebirds during fall migration in the prairie pothole region

Abstract

Abstract.-Wetland habitats in the Prairie Pothole Region of North America have been greatly reduced since European settlement, but the availability of managed wetlands has increased. The relative efficacy of these two habitats for meeting energetic demands of migrating shorebirds is unknown. To assess the relative suitability of stopover sites, we measured plasma metabolites and creatine kinase in Least Sandpipers (Calidris minutilla), Semipalmated Sandpipers (C. pusilla), and Pectoral Sandpipers (C. melanotos) at natural and managed wetland sites during fall migration in northeastern South Dakota and westcentral Minnesota. We used stepwise multiple regression to identify significant effectors of plasma metabolite levels, followed by analysis of covariance to compare metabolite values between birds in the two habitat types. Plasma metabolite levels generally did not differ significantly between birds in the two habitat types, with two exceptions. Plasma triglycerides of Pectoral Sandpipers were 2.6× higher at managed than at natural wetlands, suggesting higher rates of fattening at managed sites, but this was not supported by plasma glycerol levels, which did not differ significantly between birds in the two habitat types, or by body mass, which was greater for adult males in natural wetlands. Plasma creatine kinase levels of Least Sandpipers were 75% higher at managed than at natural wetlands, which suggests that repair of flight-induced muscle damage may be slower for this species at managed wetlands. The general absence of significant differences in plasma metabolites among shorebirds in the two wetland types suggests that natural and managed wetlands serve as similarly effective stopover habitat for fall-migrating shorebirds in the Prairie Pothole Region.© 2013 by The American Ornithologists' Union. All rights reserved.