Across North America, bird species are expected to undergo a reshuffle due to climate change, with some moving their ranges northward as temperatures and habitats alter, while others are expected to simply lose out. Now a new study—one of the first to use sophisticated modeling to look at the potential fate of one individual species, the Acadian flycatcher, across the Central Hardwood Forest region—reveals the impact increasing temperatures will have on the songbird population. 

The forest flycatcher, known for its emphatic "pee-za!" call, is common across the 96-million-acre ecosystem spreading across the central Midwest. By modeling the breeding success or failure of thousands of individual nests, the study’s research team was able to predict the bird’s population in 2100. They discovered that if current warming trends stay the same, the flycatcher faces extinction over the next 90 years.

Even a few years ago, this type of study would not have been possible, says Tom Bonnot of the University of Missouri’s School of Natural Resources and the lead author of the study, published in the journal Nature Climate Change. But two factors came together to make it possible. First was a breadth of data: Coauthor Frank Thompson, a Forest Service wildlife biologist, had collected 20 years of nesting data on the Acadian flycatcher, and coauthor Andrew Cox recently performed a meta-analysis on that information, creating good estimates of the bird’s breeding success based on temperature. For the flycatchers, the main danger when the mercury goes up is the increased activity of predators. Snakes in particular become more active, snacking on bird eggs during nesting season. 

The second factor was the advance in computing power. Even a few years ago, the team would have had to book time at a supercomputer to analyze their data, an expensive prospect. But they were able to do their modeling on what amounts to a souped-up desktop computer.

To model the fate of the flycatcher, the team divided its 96-million-acre range into 120-by-120-meter squares, assuming a bird nests in all suitable habitat. They then ran algorithms modeling the chances of survival for each nest every day during the 90-day breeding season, repeating the process for each of the next 91 years. They also modeled three different climate scenarios.

In the rosier two scenarios, in which greenhouse gas emissions are stabilized, breeding success dropped until about 2050, but then leveled out. In the third scenario, in which greenhouse gas emissions stay at current levels, the birds eventually fledge less than one bird per nest, leading to a 34 percent chance that the population crashes to eventual extinction. The scenario doesn’t just apply to Acadian flycatchers, a relatively common bird. Bonnot believes the model likely applies to many other bird species, though researchers do not have the same level of data about nesting success to create similar models.

The model accounts for uncertainty, according to Bonnot, but without solid data it’s difficult to say how other factors will impact the flycatchers, such as how land use in the United States will change over the next century and how conditions in the flycatcher’s winter range in Central and South America could impact its population. What the study does show, however, is the impact of even small changes in climate for birds. “One of the things I was most surprised by is that the kinds of temperatures we modeled in the paper were not extreme on a daily basis,” Bonnot says. “We were not simulating 110-degree days. We actually capped the temperatures below the maximum observed in nesting studies. What’s going on is that there are these small, intricate changes in patterns. There are just more days with warmer temperatures, and right there alone it was enough to drive the changes we saw.”

Brooke Batemen, director of Climate Watch at the National Audubon Society, which monitors climate change’s effect on birds, agrees that even small changes in climate can have big impacts. The increased snake predation modeled in this study wasn’t even on her radar screen, but warming is already having an impact on bird behavior. For instance, many species have already shifted their wintering ranges hundreds of miles northward to beat the winter heat. There are other changes as well.

“One thing we’ve seen is a shift in when birds breed. New studies show some species are changing their nesting period and when they arrive during migration,” she says. “That signal is getting stronger and stronger, and we’re seeing more species respond to changes in temperature. It’s a good response to physiological stress, but it could be dangerous if it leads to mismatches with things like caterpillar abundance. If birds nest earlier, they may not have enough resources for their young.”

Many birds have built-in genetic resources for dealing with climate change and can adapt, Bateman explains, though humans have thrown a wrench into the works. “The really important thing is all of this has happened in the past and birds have been through changes in climate,” she says. “But now it is happening rapidly.”

Bonnot says that in the future he wants to be able to include these types of adaptations in his models and wants to be able to model a species across its entire range, not just one ecosystem. “One of the big questions we have is, along with the risks of climate change, what is the potential for a species to adapt?” he says. “Migrating earlier and shifting northward have very important consequences across the range. If we show declines in the Midwest, would a larger model offset that, showing they are moving to cooler climates northward? If these adaptations are true, it will lessen the risks for these species.”

Modeling those adaptations, however, will require a lot more data from the field, which will take time to collect. Time the birds may not have.