Climate change is predicted to reduce sympatry among North American wood-warblers

Anthropogenic climate change will dramatically alter species distributions. The rate and magnitude of range shifts, however, will differ among taxa, resulting in altered patterns of co-occurrence and interspecific interactions. We examined potential climate-mediated breeding range shifts among North American wood-warblers (Parulidae), a speciose avian family likely to be especially impacted by such changes due to high levels of interspecific competition and hybridization. We used publicly available species distribution model (SDM) range outputs to compare current ranges and patterns of sympatry among warbler species to future ranges and sympatry under 1.5 degrees C, 2.0 degrees C, and 3.0 degrees C of average global warming. Range overlap among species and number of sympatric species are expected to decrease significantly in future warming scenarios, and unequal range shifts will alter the composition of warbler communities. On average, climate change will result in net decreases in the local species diversity; each warbler species is predicted to gain sympatry with approximately 1 new species and lose sympatry with approximately 2 species. Climate-mediated changes are predicted to differ among warblers in different regions of North America, with greatest impacts on eastern and boreal forest species. Our findings suggest that climate change will alter the diversity of wood-warbler communities during this century. Targeted monitoring of these changing interspecific relationships, especially for antagonistic interactions or hybridization between newly sympatric species, will be crucial for prioritizing particular species and regions in future conservation or management efforts. Lay Summary center dot Different rates and magnitudes of range shifts driven by climate change can lead to new patterns of range overlap among species. center dot Changing patterns of range overlap can, in turn, change species interactions, resulting in altered patterns of competition and hybridization, for example. center dot We compared current patterns of range overlap among North American wood-warblers (Parulidae) to predicted patterns with climate change using publicly available species distribution models. center dot On average, each warbler species is predicted to gain sympatry with approximately one new species, while at the same time experiencing decreases in breeding range area, range overlap among species, and overall number of sympatric species, leading to changes in community composition. center dot These results suggest that climate-induced changes in species interactions, especially among newly sympatric species, will be crucial to consider in future conservation efforts.