Wood Thrushes Connect Bird Lovers Across Borders

It’s hard to protect a bird’s habitat when you don’t know where it lives half of its life. And the Wood Thrush needs all the help it can get—the species’ population has declined by about two percent each year since 1966, according to Breeding Bird Survey data, leading conservation scientist Peter Marra to fear that the Wood Thrush will be “the next passenger pigeon.”

Marra, who heads up the Smithsonian’s Migratory Connectivity Project, suspects that habitat disruption, climate change, cats, or other anthropogenic disturbances are responsible for the threatened bird’s decline, but at this point it’s impossible to nail down the cause(s) definitively. That’s because even though we know the little birds head south to Latin America for the winter, no one’s exactly sure where in that area they end up. “We need to figure out where they’re dying, but it’s hard to find these birds,” he says. So a couple years ago, Marra started talking with Matt Jeffery, deputy director of Audubon’s International Alliances Program, about a citizen science project to help the birds.

For Jeffery, the project provided an opportunity to practice an approach to conservation that he’s long been interested in: connecting bird-lovers in the States to bird-lovers abroad. After all, birds don’t know or care what country they’re in, and the people trying to protect them shouldn’t stop their efforts just because they run into a border. So Jeffery recruited two chapters—North Carolina’s Forsyth Audubon Chapter and New York’s Bedford Audubon Chapter—and set to work.   

But before they could start making international connections, Jeffery and Marra had to figure out where exactly the Wood Thrushes winter. The latest generation of geolocator tags, which use the same technology as a portable GPS, can pin a bird’s location to within 10 meters. That’s a huge upgrade from the next-best tracker, which pins birds within a 100-kilometer radius, with a margin of error almost that big. (This kind of technology, which was used in a recent study to track Prothonotary Warblers, is useful for a species whose ultimate winter destination was previously completely unknown, but the data take a lot more time to interpret and are ultimately less actionable.)  With the latest trackers, you go from having an idea of what country the bird visits to knowing exactly what habitats and Important Bird Areas (IBAs) they’re using, and at what times, says Jeffery—pretty useful information if habitat protection is on the conservation agenda.  

The problem is that these geolocators are pricey—$465 each—so, as is often the case, the first step in the project was raising the dough. Fortunately, says Kim Brand, Bird-Friendly Communities Coordinator for Audubon North Carolina, the idea that “we were going to find something out that no one else knew about these birds,” really inspired people. It also apparently convinced them to open their checkbooks. Ninety chapter members ended up contributing, and the Forsyth Audubon Chapter raised $15,000, enough to fund the research for two full years. Up in New York, Bedford Audubon had the benefit of having a banding station already up and running, so though they raised a little less, they were also ready to take on the project.

Researchers from Marra’s team headed out to each location to oversee the research, and with banding permits and equipment borrowed from their state office, 27 Forsyth chapter members logged more than 500 hours last year helping to band. “It was seven days a week,” according to Brand. Some people even took days off work to help with the program. 

“For many people, this was the first time they held a bird in their hands,” Brand says.  

Toting their pricy new packs, the birds took off for their winter hideaway, and the volunteers went back to their normal lives. Then, when spring finally came, the real work began, as the chapters had to recapture the same birds and remove the data-laden backpacks. (Weighing in at less than two ounces, the Wood Thrush couldn’t handle the relatively heavy antenna that could have tracked their location in real time.)

Recapturing a banded bird is like trying to find a needle in a haystack, except the needle keeps flying around and the haystack is infinite—Wood Thrushes don’t have high site fidelity, which means they flit around to slightly different breeding locations year after year. Of the 22 tagged thrushes in each location, each chapter was only able to recapture two birds, and one of the geolocators Forsyth Audubon managed to collect had a dead battery (they’ve sent it back to the manufacturer, and they may receive data from it eventually). But it didn’t really matter, because one GPS is really all you need—plug it in, and voila! The bird’s whereabouts for the past 12 months are immediately available.   

That’s how Forsyth Audubon figured out that their tagged bird had spent its winter in Belize. That was well inside the expected range—in fact, it was almost comically on-the-nose. Chapter members had suspected their birds might go there, and in 2014, they had traveled to Belize to collaborate with the Belize Audubon Society on a series of other projects. Now they had proof.  During the 2014 winter trip, says Jeremy Reiskind, former president of the chapter, the North Carolina Auduboners and the Belize society members connected over the Wood Thrush, even though the North Carolinians didn’t realize the birds they were spying on could be the same birds that flitted about their own homes in summer. When the Forsyth Auduboners realized that the Belize Auduboners had never heard the Wood Thrush’s mating song—the bird only mates on the North Carolina side of its life— Reiskind and the group played it for them, to great applause. 

Bedford’s birds, meanwhile, traveled to Nicaragua. Once they got their data, Janelle Robins, executive director of the chapter, showed it at a board meeting, and she’s still struck by “the look on their faces when they saw the map,” she says. “It’s something that’s so tangible, that speaks to anyone, no matter if they’re a scientist or not.” The chapter is currently researching the best way to help protect the habitat down there.

Monitoring of these habitats is particularly important right now—climate change threatens 80 percent of the Wood Thrush’s summering ground in the States, according to Audubon’s Birds and Climate Change report. And even though we tend to think of climate change as something “just happening up north,” Marra says, climate-induced changes to precipitation may be a threat to the bird’s wintering grounds, too, so any extra monitoring of the birds and their habitat will help.

Along those lines, Forsyth Audubon is already planning a trip down to Belize to help out with the Christmas Bird Count this winter. They’re also working to create a series of signs to be displayed in the Wood Thrush’s Belize habitat that will tell the birds’ story and encourage people to protect the habitat.

The project has turned something abstract into something concrete, Jeffery says. Now they know that “our bird in our backyard travels to this forest in Belize, and if we want that bird to return, we have to invest down there.” Reiskind says he hopes to return to Belize this winter. “To me, what we have done is really the essence of citizen science,” he says. Hopefully he’ll see some familiar faces—both bird and human—when he’s there.