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How temperature and elevation shape birds across geographic space and a changing climate

Monday, October 17, 2022 at 2pm Eastern/1pm Central/12pm Mountain/11am Pacific Time
This webinar is FREE but registration is required. Register Here
Understanding how the environment shapes the physical structure of species is important not only for elucidating the drivers of biodiversity, but also for predicting how species will respond to ongoing global change. However, despite a clear set of expectations, we have largely lacked broad-scale evidence in support of generalizable effects of the environment on morphology. For example, evidence for and causal factors behind Bergmann’s Rule, the notion that animals are generally larger at higher latitudes, continue to be debated.
Using data from more than 250,000 captures encompassing over 100 bird species from the Monitoring Avian Productivity and Survivorship (MAPS) Program, we assessed how the size and shape of birds varies across the North American continent, and how this has shifted over the past three decades. Within species, we find that warmer temperatures are generally associated with smaller individuals, both at more equatorial latitudes and in more recent years. Morphology can vary substantially within species. Stronger responses to spatial - rather than temporal - variation in temperature suggests that morphological change, however, may not be keeping up with the pace of climate change. Additionally, as elevation increases, we found that, within-species, body size declines as relative wing length increases, likely due to the benefits that longer wings confer for flight in thin air environments. These results provide support for both existing and new large-scale ecomorphological ‘rules’ and highlight how the response of functional tradeoffs to abiotic variation drives morphological change. This work, enabled by the efforts of MAPS banders across North America, will serve as the basis for future exploration of the multitude of factors that drive the size and shape of birds across both space and time.
Dr. Casey Youngflesh is Quantitative Ecologist and Presidential Postdoctoral Fellow in Ecology, Evolution, and Behavior at Michigan State University. His research, broadly speaking, seeks to understand population- and community-level ecological processes across environmental gradients.