The ecological impacts of modern global climate change are detectable in a wide variety of phenomena ranging from shifts in species ranges to changes in community composition and human disease dynamics. Thus far, however, little attention has been given to temporal changes in spatial synchrony—the coincident change in abundance or value across the landscape—despite the importance of environmental synchrony as a driver of population trends and the central role of environmental variability in population rescue and extinction. We examined temporal changes in spatial synchrony among North American wintering bird species using Christmas Bird Count data and tested whether patterns were potentially due to coincident changes in mean temperatures or rainfall.
Results/Conclusions
We found that spatial synchrony of a significant proportion of 49 widespread North American wintering bird species has increased over the past 50 years and that these patterns were mirrored by significant increases in spatial synchrony of mean maximum air temperature, primarily during the summer, across North America. These findings suggest the potential for increased spatial synchrony in environmental factors to be affecting a wide range of ecological phenomena. These affects are likely to vary, but for North American wildlife species, increased spatial synchrony driven by environmental factors may be the basis for a previously unrecognized threat to their long-term persistence in the form more synchronized population dynamics reducing the potential for demographic rescue among interacting subpopulations.