Modeling Wetland Blackbird Populationsas a Function of Waterfowl Abundance in the PrairiePothole Region of the United States and Canada

摘要

Blackbirds share wetland habitat with many waterfowl species in Bird ConservationRegion 11 (BCR 11), the prairie potholes. Because of similar habitat preferences,there may be associations between blackbird populations and populations of one ormore species of waterfowl in BCR11. This study models populations of red-wingedblackbirds and yellow-headed blackbirds as a function of multiple waterfowl speciesusing data from the North American Breeding Bird Survey within BCR I I. For eachblackbird species, we created a global model with blackbird abundance modeled as afunction of 11 waterfowl species; nuisance effects (year, route, and observer) alsowere included in the model. Hierarchical Poisson regression models were fit usingMarkov chain Monte Carlo methods in WinBUGS 1.4.1. Waterfowl abundances wereweakly associated with blackbird numbers, and no single waterfowl species showed astrong correlation with any blackbird species. These findings suggest waterfowlabundance from a single species is not likely a good bioindicator of blackbird abun-dance; however, a global model provided good fit for predicting red-winged blackbirdabundance. Increased model complexity may be required for accurate predictions ofblackbird abundance; the amount of data required to construct appropriate modelsmay limit this approach for predicting blackbird abundance in the prairie potholes.