As climate change spreads across America, some areas are getting wetter and others hotter and drier. A new study of the yellow warbler, a widespread migratory songbird, shows that individuals have the same climatic preferences across their migratory range. The work will be published on February 17th in Ecology letters.
"What is amazing is that the birds follow similar climates even though they have migrated thousands of kilometers," said Rachael Bay, assistant professor in the Department of Evolution and Ecology, College of Biological Sciences, University of California at Davis. "It seems that individual birds can be adapted to specific climatic regimes."
Yellow warblers (Setophagia petechia) breed across North America and fly south to Central and South America to spend the winter. An earlier study by Bay and colleagues found links between genetic variation and rainfall in North America, suggesting that certain individuals might be adapted to dry conditions while others thrive in humid conditions. In the current study, the authors were able to use genetics to predict where birds caught in their wintering areas in Central and South America would breed and compare climate patterns in their winter and summer areas.
Individual birds preferred drier or wetter areas, but not warmer or cooler areas. In other words, birds that breed in relatively arid parts of North America – like California's Central Valley – overwintered in arid parts of South or Central America.
"This is the first demonstration of the use of individual genetic tracking to link climate across the migration cycle within a bird species," said Bay.
Effects of climate change
These different climate preferences could have consequences for the response of birds to climate change. Bay speculates that the variation she and her colleagues found could provide the raw material for adapting the species to changing climatic conditions. For example, populations that are adapted to drier conditions can replace those that are adapted to wetter conditions. In fact, Bay and colleagues have already found that the population size of the yellow warblers has changed over the years with rainfall.
Bay collected data for the study during her postdoctoral research in collaboration with banding stations and collection points in North and South America. Bay and her colleagues are now curious to see whether individuals of other bird species also follow the climate during migration.
Other authors on the paper include Daniel Karp, Department of Wildlife, Fish and Conservation Biology, UC Davis; James Saracco, Bird Populations Institute, Petaluma, California; William Anderegg, University of Utah; Luke Frishkoff, University of Texas at Arlington; David Wiedenfeld, American Bird Conservation, The Plains, Virginia; Thomas Smith, UCLA; and Kristen Ruegg, Colorado State University, Fort Collins.
The work was supported by grants from the National Science Foundation, National Geographic, the California Energy Commission, and First Solar Inc.