Climate Change and Birds of the Acadia National Park Region: Projected Changes in Habitat Suitability for 130 Breeding Bird Species
Climate change is affecting species and resources across national parks. Stewarding resources for continuous change is a challenge for park managers; however, understanding projected rates and directions of change should facilitate monitoring, management, and visitor education on park lands. To support such efforts for Acadia National Park, we analyzed projected changes in bird habitat suitability for 130 North American breeding bird species (primarily terrestrial [landbird] and some freshwater species) for three future periods (2040, 2070, and 2100). We present model output from two climate scenarios, the ‘least change’ and ‘major change’ scenarios that represent plausible lower and upper bounds of future climatic conditions. Looking out to 2100, general trends in the data indicate decreasing habitat suitability under both climate scenarios for 30 species (23% of species analyzed), no change under both scenarios for 15 species (12%), increases or new habitat for 48 species (37%), and mixed results (i.e., different change classes among climate scenarios) for 37 species (28%). Projected changes in habitat suitability varied by habitat preference and migratory status. For example, extant Neotropical migrants, such as the magnolia and black-throated green warblers, generally show decreases in potential habitat and many previously rare or absent Neotropical migrants gain substantial potential habitat in the future, suggesting a possible large turnover in long-distance migrants found in the park during summer months. Similarly, extant forest birds have relatively low suitability projections, but forest is also the habitat type with the greatest number of new bird species (n = 12). Under the ‘major change’ climate scenario, several species previously absent or rare in the Acadia region, such as the summer tanager, worm-eating warbler, and hooded warbler, are likely to have suitable habitat gains by the end of the 21st century. Resident birds, such as the northern cardinal and white-breasted nuthatch, generally maintain or have increases in potential habitat over the next several decades. Birds, as highly mobile species able to track a shifting climate and as resources of keen interest to many park visitors, are ideal bellwethers of change within parks and useful examples for educating the public on how ongoing climate change is affecting park resources.