This project aims to assess climate-driven changes in the phenology (timing) of migratory birds and their food sources. Climate change is expected to alter the synchronized relationship between the timing of migratory bird arrival and nesting on breeding grounds, and the peak availability of key food sources such as insects. As temperatures rise, trees and plants generally flower earlier, and associated insects also peak earlier. Yet migratory birds may not be able to sufficiently advance their migration to maintain optimal food availability for their young. Using historical data on the timing of bird migration and tree flowering (an indicator of food availability), this project will calculate annual phenological synchrony and overlap (where synchrony is the temporal difference between peak bird presence and peak tree flowering, and overlap is the portion of co-occurring bird presence and tree flowering). In addition to evaluating the effect of climate change on changes in overlap and synchrony, this project will also analyze differences in trends between various groups of migratory birds (i.e.., long- versus short-distance migrants), thereby shedding light on the ecological mechanisms driving phenological responses to climate change in migratory birds.
USGS National Climate Change and Wildlife Center: Assessing Climate-Driven Changes to Phenology (Timing) of Migratory Birds and Their Food Sources