title: The pace of past climate change vs. potential bird distributions and land use in the United States.
abstract: Climate change may drastically alter patterns of species distributions and richness, but predicting future species patterns in occurrence is challenging. Significant shifts in distributions have already been observed, and understanding these recent changes can improve our understanding of potential future changes. We assessed how past climate change affected potential breeding distributions for landbird species in the conterminous United States. We quantified the bioclimatic velocity of potential breeding distributions, that is, the pace and direction of change for each species' suitable climate space over the past 60 years. We found that potential breeding distributions for landbirds have shifted substantially with an average velocity of 1.27 km yr(-1) , about double the pace of prior distribution shift estimates across terrestrial systems globally (0.61 km yr(-1) ). The direction of shifts was not uniform. The majority of species' distributions shifted west, northwest, and north. Multidirectional shifts suggest that changes in climate conditions beyond mean temperature were influencing distributional changes. Indeed, precipitation variables that were proxies for extreme conditions were important variables across all models. There were winners and losers in terms of the area of distributions; many species experienced contractions along west and east distribution edges, and expansions along northern distribution edges. Changes were also reflected in the potential species richness, with some regions potentially gaining species (Midwest, East) and other areas potentially losing species (Southwest). However, the degree to which changes in potential breeding distributions are manifested in actual species richness depends on landcover. Areas that have become increasingly suitable for breeding birds due to changing climate are often those attractive to humans for agriculture and development. This suggests that many areas might have supported more breeding bird species had the landscape not been altered. Our study illustrates that climate change is not only a future threat, but something birds are already experiencing.
authors.affiliation: SILVIS Lab, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Brooke L
authors.initials: BL
authors.lastname: Bateman
authors.affiliation: SILVIS Lab, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Pidgeon
authors.affiliation: SILVIS Lab, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Volker C
authors.initials: VC
authors.lastname: Radeloff
authors.affiliation: Centre for Tropical Biodiversity and Climate Change Research, School of Marine and Tropical Biology, James Cook University, Townsville, Qld, 4811, Australia.|Division of Research and Innovation, James Cook University, Townsville, Qld, 4811, Australia.
authors.forename: Jeremy
authors.initials: J
authors.lastname: VanDerWal
authors.affiliation: U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WI, 54603, USA.
authors.forename: Wayne E
authors.initials: WE
authors.lastname: Thogmartin
authors.affiliation: Center for Climate Research, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Vavrus
authors.affiliation: U.S. Fish and Wildlife Service, La Crosse, WI, 54603, USA.
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Heglund
mesh_terms: D063147:Animal Distribution; D000818:Animals; D044822:Biodiversity; D001717:Birds / Q000502:physiology*; D057231:Climate Change; D008954:Models, Biological; D013045:Species Specificity; D013997:Time Factors; D014481:United States
keywords: Maxent; North American breeding landbirds; anthropogenic land use; climate change; distribution shifts; species distribution model; species richness