Using citizen science data to predict distributional responses of birds to climate and landcover

Changes in land-use and its associated effects on species distributions have been well studied, resulting in strong conservation action. Climate change has also demonstrated the potential to significantly alter species distributions across broad spatial scales. Thus, quantifying the impacts of climate change relative to landcover will be important to anticipate changes in species distributions and implement effective regional conservation strategies. Here we combine two analyses (both using randomForest methodologies) to link the contemporary directional changes in bird distributions with projected future change in forest bird habitat. We modeled distributions for 103 bird species using citizen science data collected from two discrete breeding bird atlas projects in Ohio (1982-1987 and 2006-2011) with climate and landcover data. To assess performance, models were back-projected with environmental data from the first atlas to quantify actual change. Then, to explore changes across broader spatial and temporal scales, we modeled 88 forest bird distributions based on North American Breeding Bird Survey data with predictors of climate, elevation, and tree species composition. These models were projected into the future to assess potential trajectories of habitat changes and bird distributions for each decade until 2070, when temperature increases in the eastern United States will likely reach or exceed ~2ºC. Each modeling approach illustrates the importance of both landcover and climate in describing changes in avian distributions and demonstrates the utility of citizen science data for conservation planning in the face of increased environmental pressures.