We humans have our ways of coping with climate change: We'll put down sandbags, escape pods, and even heat siphons to keep our homes from slipping away. But what about birds? How are they surviving bizarre rain patterns, extreme temperatures, and freak weather events?
Brooke Bateman has the answer to that. The post-doctorate ecologist from the University of Wisconsin, who once deciphered movements of Australian animals, wanted to figure out how breeding birds in North America were dealing with the havoc brought on by climate change. “How far and fast is climate change happening . . . that’s what I needed to know,” she says. With the help of scientists from Wisconsin and Australia, Bateman wove together climate data with location data for 285 North American species, and built models to show how rainfall, temperature, weather, and other variables affected every species’ distribution for every month of every breeding season from 1950 to 2011. (“I made a lot of models,” Bateman says.) Using the models as a reference, she then drew predictions on where the birds are ending up. The final results were published in Global Change Biology in December.
What do the models reveal?
There are two major curveballs in this study: First, birds are moving faster than we think, and second, they’re going places where we don’t suspect. Previous estimates had breeding ranges shifting by an average of .4 miles a year, but Bateman’s work proves that some species are moving at twice that speed, up to as much as 3 miles a year. The quickest drifters include meat eaters, insect eaters, and species that forage high up in the canopy or at the bottom of the forest floor (they’re probably stalking their prey to new spaces). Birds that are staying put include woodpeckers, hummingbirds, plant eaters, and non-migrants.
The direction of these movements is also unexpected. While the majority of the species are flying northward (as predicted), more than a quarter of them are creeping westward—specifically to Wisconsin, Minnesota, Iowa, and South Dakota. The Tufted Titmouse, for example, is expanding into the Midwest and finding its niche in human-dominated landscapes. Hooded Warblers are moving in that direction as well, but they’re more used to living in the thick forest understory, so adapting to the grasslands and wide-open plains will be a lot more difficult for them.
How does this study fit in with other related research?
In the continued saga of birds and climate change, findings like these can “help to complete the story,” Gary Langham, Audubon’s chief scientist, says. While the Audubon Birds and Climate Change Report (released in 2014) predicts how breeding and wintering ranges may shift and shrink over the next century, Bateman’s models take a deeper look at what’s causing the birds to relocate right now. And the snapshots from the past 60 years show that birds are already moving thanks to global warming. The responses, Langham says, are idiosyncratic: The birds aren’t just moving northward, and they’re not all magically adapting to their new surroundings.
The study’s present-day, species-specific approach is also important because it highlights which birds need the most help. For instance, Bateman’s models show that the Florida Scrub-Jay’s thin slice of habitat is being squeezed even more tightly. The Audubon Climate Report’s models point out that there will be other climate-suitable patches in California for these birds; but the jays probably won’t be able to find their way out there, Langham says. So rather than leaving species to adjust—or go extinct—on their own, humans will have to step in and give them a hand, by slowing down the pace of climate change and preserving critical landscapes.
Why is this helpful for conservation?
In Bateman’s perspective, birds have three options: They can move, stay and adapt, or stay and be wiped out. Knowing which option a species will choose can help conservation groups, like the U.S. Fish and Wildlife Service (one of Bateman’s collaborators), pick out a rescue strategy. “We can put our money in places that have multiple species, and build connectivity between where the birds are and where they will be,” Bateman says. Unfortunately, birds and people tend to love the same landscapes: In the study, areas that gained the most species were also hot spots for development. Saving these lands through acquisition is crucial, Bateman says.
The study also offers some foresight on which spaces need to be preserved for current and future generations of birds. Survival isn’t the only thing species have to worry about when moving to a new breeding spot: "The big question is, can they create the next successful generation there?" Langham says. If they can’t, humans might need to step in. “Heroic efforts [by people] could buy at least 10 more generations of birds,” Langham says, “and that could be the difference in them being around.”