Dr Morgan Tingley1, Dr Jacob Socolar1, Dr Steven Beissinger2, Dr Peter Epanchin3
1University of Connecticut, Storrs, USA, 2University of California, Berkeley, USA, 3US Agency for International Development, Washington, USA
Global change ecology predicts that, under a warming climate, consumers such as birds should shift their geographic distributions to track temperature and should adjust their breeding phenology to track resource emergence. However, range shifts and phenological shifts are likely to interact. Geographically shifting species might occupy new locations with different resource phenology, while phenologically shifting species might experience different temperatures during key life-history events. We explore the possibility that avian phenological advancement reduces ambient temperatures under which birds breed, thereby reshaping expectations for how birds should shift geographically to track temperature. To do so, we apply novel formulations of community occupancy models to estimate the magnitude of breeding season phenological shift in the Californian avifauna over the last century. We use this estimate to compute the mean change in temperature resulting from this phenological shift during the breeding season – when phenological advancement could expose ectothermic nestlings to colder temperatures. Across the Californian avifauna, the data support an average phenological advancement of 5–12 days over the 20th century. In June, when nestlings are largely ectothermic, this shift lowers average temperatures by over 1°C, a difference similar to the total warming experienced over the past century. We propose phenological shifts as an overlooked mechanism for thermal niche tracking, with the potential to reshape both the need and opportunity to shift geographically.
Dr. Tingley is an Assistant Professor of Ecology and Evolutionary Biology at the University of Connecticut. His research centers on the effects of global change on animal communities, specializing in montane birds. He has also served on the Organizing and Scientific Steering Committee for this Species on the Move conference.