Bird strategies connected to different climate challenges

Some birds live fast and die young. Others live life in the slow lane and reach ripe ages. Researchers found climate affects birds that use both of these strategies in different ways. These findings have implications for birds’ ability to persist as the globe warms.

“The question now is, which ones have the capacity to adapt fast enough, or to shift their ranges and move to track the changing climate, and some of them may not,” said Kelly Kapsar, a data scientist with the Institute for Biodiversity, Ecology, Evolution and Macrosystems (IBEEM) at the Michigan State University.

Kapsar, a postdoctoral researcher with IBEEM at the time, co-authored a study with an interdisciplinary team of scientists published in Ecology Letters—all part of the MSU Ecology, Evolution and Behavior Program—tapping into publicly available data sources like remote sensing data on climate and bird distribution data around the world. Their goal was to find out how climate relates to these different life history strategies in nonmigratory birds.

“We’re trying to find these deep, evolutionary signatures in terms of birds’ life history,” she said. “In order to get those big signatures, you have to have a large sample and look globally to see through all of the noise and find those patterns.”

But manually finding those patterns wasn’t easy, so Kapsar and her colleagues turned to supercomputers at the university to help them out and organize the massive amounts of data. Then, the team used a statistical model to determine how climate is associated with long-lived and short-lived species.

When it came to climate, the researchers paid attention to inter- and intra-annual variability. Inter-annual variability refers to changes between years, like a cold year versus a hot year. Intra-annual variability refers to changes within years, like having cold winters and warm summers.

The team found that inter-annual variability was associated with a slower pace of life. These species, like the sulphur-crested cockatoo (Cacatua galerita), can hedge their bets and skip reproduction one year if the weather isn’t suitable. In areas with high intra-annual variability, species like backyard cardinals live fast. “They get all their reproducing done,” Kapsar said.

Kaspar said birds with both strategies are experiencing a faster rate of change than they have experienced in their evolutionary time. In addition, they are facing extreme climatic events like heat waves or droughts. Unlike migratory birds that can move to track food or avoid the stress of a cold winter, nonmigratory species don’t have that option. For example, long-lived species adapt more slowly than short-lived birds. On the other hand, species that only live a few years are out of luck if they experience multiple bad years in a row.

“We can rely on this basic understanding about how they’re distributed today, with respect to inter-annual and intra-annual variability that helps us make insights about the fact that some are going to be way more susceptible than others, just because they inherently don’t have the capacity to respond quickly enough,” Kapsar said.

There’s also variability within species, said Phoebe Zarnetske, a professor at Michigan State University and director of IBEEM who led the study. For example, tropical species that have less variation in body size are more susceptible to environmental change, she said. “Species that are all basically the same size or have very similar trait values for a certain trait don’t have as much capacity to withstand these changes,” she said. “Whereas species that are made up of individuals with a wide range of body sizes, for example, there are more individuals that can deal with conditions in one part of the range versus the other.”

In addition to Kapsar and Zarnetske, the study was led by Casey Youngflesh and co-authored by Adriana Uscanga, Peter Williams, Jeffrey Doser, Lala Kounta.