Changes in nutrient dynamics of midcontinent greater white‐fronted geese during spring migration

Abstract

AbstractWaterfowl and other migratory birds commonly store nutrients at traditional staging areas during spring for later use during migration and reproduction. We investigated nutrient‐storage dynamics in the midcontinent population of greater white‐fronted geese (Anser albifrons; hereafter white‐fronted geese) at spring staging sites in the Rainwater Basin of Nebraska during February–April and in southern Saskatchewan during April–May, 1998 and 1999. In Nebraska, lipid content of white‐fronted geese did not increase, and protein content changed little over time for most age and sex categories. In Saskatchewan, lipids increased 11.4 g/day (SE = 1.7) and protein content increased 1.6 g/day (SE = 0.6) in the sample of adult geese collected over a 3‐week period. A study conducted during 1979–1980 in the Rainwater Basin reported that white‐fronted geese gained 8.8–17.7 g of lipids per day during spring, differing greatly from our results 2 decades later. In addition, lipid levels were less in the 1990s compared to spring 1980 for adult geese nearing departure from staging sites in Saskatchewan. This shift in where geese acquired nutrient stores from Nebraska to more northern staging sites coincided with a decrease in availability of waste corn in Nebraska, their primary food source while staging at that stopover site, and an increase in cultivation of high‐energy pulse crops in Saskatchewan. White‐fronted geese exhibited flexibility in nutrient dynamics during spring migration, likely in response to landscape‐level variation in food availability caused by changes in agricultural trends and practices. Maintaining a wide distribution of wetlands in the Great Plains may allow spring‐staging waterfowl to disperse across the region and facilitate access to high‐energy foods over a larger cropland base. © 2011 The Wildlife Society.