Behavior of Migrating Shorebirds at North Dakota Prairie Potholes

Abstract

We examined diurnal time-activity budgets of American Avocets (Recurvirostra americana). Long-billed Dowitchers (Limnodromus scolopaceus), Stilt Sandpipers (Calidris himantopus). Semipalmated Sandpipers (C. pusilla), and Least Sandpipers (C. minutilla) in the Prairie Pothole Region of northwestern North Dakota during spring and fall 1994 and 1995 to evaluate the importance of prairie pothole wetlands to a variety of shorebird guilds. Long-billed Dowitchers, and Stilt, Semipalmated, and Least Sandpipers spent most of their time feeding in spring and fall. American Avocets also used prairie potholes for feeding, but other activities like locomotion, body maintenance, and sleep consumed large proportions of time. Time spent in various behaviors was similar among three diurnal (early, midday, and late) time periods during spring and fall. Avocets and dowitchers slept more during midday than early or late periods. Flock size was smaller during spring than fall in both years for American Avocets, Long-billed Dowitchers, Semipalmated Sandpipers, and Least Sandpipers and in 1994 for Stilt Sandpipers. More than half of all aggressive encounters by American Avocets, Stilt Sandpipers, Semipalmated Sandpipers, and Least Sandpipers were intraspecific during feeding. Smaller flock sizes in spring may be related to avoidance of costly aggression in spring and/or the numbers of birds migrating through the region. The Prairie Pothole Region serves as a stopover for most shorebirds to acquire energy reserves during migration, and conservation efforts should focus on preserving and enhancing prairie potholes for foraging shorebirds.