Response of waterbirds to number of wetlands in the Prairie Pothole Region of North Dakota, USA

We examined the relationship between number of wetlands and occurrence of five waterbird and one waterfowl species in the Prairie Pothole Region of North Dakota, USA, from 1980-2000. Data from 13 Breeding Bird Survey routes provided an index to regional density and distribution of Pied-billed Grebe (Podilymbus podiceps), Black Tern (Chlidonias niger), American Bittern (Botaurus lentiginosus), Northern Pintail (Anas acuta), Sora (Porzana carolina), and American Coot (Fulica. americana), while 69 segments from annual Waterfowl Breeding Ground Population and Habitat Surveys provided an index to regional wetland availability. Numbers of wetlands and birds varied among years, and density and distribution of all six species showed a strong positive correlation with number of wetlands. Correlations were weaker when the number of wetlands was lagged one year, suggesting that waterbird distributions shift in response to water availability rather than respond locally. Spatial and temporal variation of waterbird habitat and numbers should be considered in monitoring and management of waterbirds in the Prairie Pothole Region.