Date of this Version
Journal of Biogeography (J. Biogeogr.) (2011) 38, 1694–1707;
Aim We examined the influences of regional climate and land-use variables on mallard (Anas platyrhynchos), blue-winged teal (Anas discors), ruddy duck (Oxyura jamaicensis) and pied-billed grebe (Podilymbus podiceps) abundances to inform conservation planning in the Prairie Pothole Region of the United States.
Location The US portion of Bird Conservation Region 11 (US-BCR11, the Prairie Potholes), which encompasses six states within the United States: Montana, North Dakota, South Dakota, Nebraska, Minnesota and Iowa.
Methods We used data from the North American Breeding Bird Survey (NABBS), the National Land Cover Data Set, and the National Climatic Data Center to model the effects of environmental variables on waterbird abundance. We evaluated land-use covariates at three logarithmically related spatial scales (1000, 10,000 and 100,000 ha), and constructed hierarchical spatial count models a priori using information from published habitat associations. Model fitting was performed using a hierarchical modelling approach within a Bayesian framework.
Results Models with the same variables expressed at different scales were often in the best model subset, indicating that the influence of spatial scale was small. Both land-use and climate variables contributed strongly to predicting waterbird abundance in US-BCR11. The strongest positive influences on waterbird abundance were the percentage of wetland area across all three spatial scales, herbaceous vegetation and precipitation variables. Other variables that we included in our models did not appear to influence waterbirds in this study.
Main conclusions Understanding the relationships of waterbird abundance to climate and land use may allow us to make predictions of future distribution and abundance as environmental factors change. Additionally, results from this study can suggest locations where conservation and management efforts should be focused.