Global warming is changing where birds breed
Global warming is shifting the behavior of migratory birds in the eastern regions of North America. Researchers have discovered that the breeding range of some birds is shrinking, while for others this range is expanding.
A research team led by Professor Clark Rushing at Utah State University’s Quinney College of Natural Resources set out to investigate how climate change has affected where birds breed.
In collaboration with experts at the U.S. Geological Survey, the team analyzed data from the Breeding Bird Survey.
“Thousands of devoted volunteers, cooperators, and a joint U.S.-Canadian wildlife management team have contributed to the success of the surveys for the last 54 years,” said study co-author Andy Royle, a USGS senior scientist.
“The Breeding Bird Survey is fundamental to our understanding and management of wild bird populations in North America.”
Survey data was combined with computer models to reveal breeding range shifts for 32 species of birds found in eastern North America.
According to the study, birds that both breed and winter in North America are extending their ranges north where warming temperatures have created new, suitable places to breed.
The findings indicate that bird species such as Carolina wrens and red-bellied woodpeckers will be able to adapt to future climate change.
On the other hand, some birds have breeding ranges that are dwindling. Neotropical migratory birds breed in North America during the summer and migrate to the Caribbean, Central America, and South America for the winter.
Neotropical migrants include warblers, orioles, flycatchers, and other species that birdwatchers look forward to spotting in the spring. The researchers found that Neotropical birds are not expanding north, yet their suitable southern range is shrinking.
Over the past five decades, Neotropical bird populations have decreased by about 2.5 billion individuals.
“There’s a real risk that, if these declines continue at their current pace, many species could face extinction within this century,” said Professor Rushing. “Neotropical migrants are vulnerable to future climate change, putting them at risk of greater declines.”
While it would seem the birds would simply extend their range a bit farther north, the researchers suspect that conditions where the birds are wintering may not provide them with enough food and energy reserves. Many Neotropical habitats in the Caribbean, Central America, and South America are being degraded.
“That’s just one explanation,” said Professor Rushing, “and it highlights how little we know and how much more research is needed.”
The study is published in the journal Proceedings of National Academy of Sciences.