Climate

As Climate Change Threatens to Push the Bicknell’s Thrush North, Scientists Are Protecting Its Future Habitat Now

In a warmer world, to save rare species, scientists have to proactively protect their future ranges. For this alpine thrush, that means working with foresters in the Canadian mountains.

It was before dawn one morning this June, and I found myself hiking along a mossy ridge 4,080 feet above sea level with a pair of birders chasing a rare species. The breeze was sweet with balsam, and the bird chorus swelled as the first morning sun spilled over New Hampshire’s jagged White Mountains.

Laura Deming, senior biologist at New Hampshire Audubon, led the way, and a GPS led her. That morning, we’d bushwhack to five locations across several miles, stopping for 20 minutes at each to identify birdsongs and tally the crooners by species. As we walked, Deming put names to songs—Swainson’s Thrush, Fox Sparrow, Yellow-rumped Warbler—but there was no mention of the bird we were after.

Then, at the end of our first survey at around 5:45 a.m., field assistant Jane Kolias called out. “Speckled breast, reddish legs,” she said, pointing and looking through her binoculars. “He just went to the ground.” She had spotted our first Bicknell’s Thrush.

Each summer since 2000, volunteers and biologists like Deming have dispersed across northeastern fir forests to track the Bicknell’s Thrush, one of North America’s rarest songbirds. The species nests almost exclusively on mountaintops above 2,600 feet in the northeastern U.S. and Canada, where it hides among thick boughs and occasionally flits to the ground to eat insects. But the migratory bird is feeling the squeeze on either end of its range, as logging expands into its Canadian breeding grounds and agriculture expands into its Caribbean wintering habitat. A smattering of surveys in Bicknell's breeding habitat point to continual population declines since the early 1990s in the U.S., including on New Hampshire's White Mountains, and in Canada, too. But the count data are incomplete, and like the bird, its true population size remains elusive.

That’s why the three of us slept on a mountaintop and woke at 4:00 a.m. to count thrushes. Deming is one of more than 100 surveyors who together cover more than 130 routes spanning from New York to Maine each summer, and then report their findings to the Vermont Center for Ecostudies (VCE) in Norwich. There, a group of concerned conservationists works to protect this sensitive species and its dwindling habitat as part of the International Bicknell’s Thrush Conservation Group.

Founded in 2007 by VCE director Chris Rimmer, the group includes representatives from seven countries across the bird’s range, and they ambitiously aim to increase the bird’s population by 25 percent by 2060. They’ll do that by following their conservation action plan that aims to protect and expand habitat for the bird with the help of governments, industries, and non-profit groups.

The group is looking toward future threats, too. As the climate changes, warmer temperatures creeping up mountain slopes could potentially push the thrushes off their mountaintops; indeed, Bicknell’s Thrushes have already disappeared from Mount Greylock, the tallest peak in Massachusetts and only place in the state where the species has been observed. And so members of the conservation group are also studying and protecting places where the species may migrate with climate change.

In doing so, they’re helping not only the Bicknell’s Thrush, but also other plants and animals that live within its sensitive mountaintop habitats, Rimmer says. For example, the mountains the birds inhabit in their Caribbean wintering grounds are also home to endemic plants and animals only found on those islands.

“It’s a lightning rod that we are focused on as a means to conserve the whole habitat,” he says. “We are conserving a whole suite of other life forms, not just the Bicknell’s Thrush.”

Laura Deming (right), senior biologist at New Hampshire Audubon, and field assistant Jane Kolias (left) hike up Cannon Mountain in Franconia, NH after five hours of morning surveys looking for Bicknell's Thrush. Deming is one of more than 130 surveyors across the northeastern U.S. tracking this elusive songbird this summer. Photo: Laura Poppick

The group has already made progress in protecting habitat at both ends of the bird’s range. To the south, VCE worked with a local land preservation group to help form the Dominican Republic’s first private nature reserve in 2012. Called the Reserve Zorzal (or the Bicknell’s Thrush Reserve), the property spans more than 1,000 acres of predominantly cacao farmland. Roughly 70 percent of the property has been set aside as habitat, while the rest remains available for cultivation. “That was a big success,” Rimmer says. The group aims to create a network of protected properties across the Dominican Republic and Haiti where the majority of the birds winter.

To the north, the Bicknell’s breeding grounds in the U.S. fall largely within state parks and so are already protected. But much of their Canadian habitat across New Brunswick, Nova Scotia, and surrounding regions has been logged for decades. Keeping these Canadian forests dense and suitable for nesting may prove increasingly vital as climate change potentially pushes the birds off their U.S. mountaintops into Canada, says John Lloyd, director of science at VCE and current chair of the international coalition.

“As these mountaintops become less suitable for Bicknell’s Thrush and they are moving north, they are going to be moving into landscapes that are going to have much more forestry practiced on them,” Lloyd says. “So finding a way to make forestry and Bicknell’s Thrush get along together is really important in the long run.”

Members of the Bicknell’s conservation group are already working on this problem. Emily McKinnon, a postdoctoral researcher at Ontario’s University of Windsor and group member, studied the effects of logging on Bicknell’s habitat as a Master’s student. Because Bicknell’s are listed as a threatened species in Canada, logging companies could incur fines for damaging habitat—and as a result they have an incentive to keep that habitat intact, McKinnon says. In fact, the Finnish logging and paper company UPM partially funded the research.

“They were really interested in what we were finding and wanted to know where the birds were,” McKinnon says. “There was always a really good working relationship with the companies operating there.”

McKinnon found that Bicknell’s could coexist with logging as long as the companies actively left behind dense forest patches preferred by nesting birds. Several local logging companies have adjusted their practices accordingly. They’ve done this even though it’s uncertain whether the birds will migrate to this area at all; even McKinnon questions whether the species’ sparse populations will hinder their ability to leap northward.

And that’s why volunteers and biologists will continue waking up at the break of dawn to track its whereabouts on mountaintops across the northeast each summer—a rather impressive dedication for a small, plain-looking brown and white bird.

“They are really drab as far as birds go,” Kolias said as she observed that first thrush of the day through her binoculars. We found four more that morning, confirming that the species still has a place on at least this one mountaintop in the northeastern U.S.

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