Surveys document the changes that are occurring in boreal birds
By Darryl McGrath
The American three-toed woodpecker was always rare in New York, but warmer winters in the Adirondacks—probably the bird’s only stronghold in the state—may have pushed this winter-tolerant species farther north forever.
“The three-toed woodpecker is gone from the Adirondacks only in the last decade,” said ornithologist Jeremy Kirchman, the curator of birds and mammals at the New York State Museum. The bird, he said, may be the first to leave New York because of a warming climate.
As Kirchman and others monitoring climate change in the Adirondacks realize, this small, unflashy species will also probably not be the last boreal bird to dwindle in the Adirondacks and then disappear from the region.
Fifteen years ago, if you asked almost any ornithologist about the biggest threat to birds, they would have cited habitat loss. Habitat loss remains a serious problem, but now biologists better understand how changes in habitat are linked to two key elements of climate change: temperature and precipitation. In the Adirondack Park, that relationship between habitat and climate change is illustrated through two long-running surveys of boreal birds—the birds of the Northern Forest that stretches from far Upstate New York into Vermont, New Hampshire and Maine. The Adirondack Park is the southernmost range for several boreal birds.
One survey, which Kirchman started in 2013, tracks birds on Whiteface Mountain. The other, now in its 17th year, is overseen by Michale Glennon, an ecologist and senior research scientist at Paul Smith’s College’s Adirondack Watershed Institute. Glennon is following lowland boreal birds found in conifer swamps, open peatlands and open river corridors.
Both surveys got considerable attention five and six years ago when their findings were first released, but the effort didn’t stop there. Glennon and Kirchman have continued their original surveys, with a commitment to carry the research forward for many more years. If they can do that, they will have compiled a treasure trove of data about Adirondack boreal birds in contrasting habitats that will serve as a precious historical record and could guide decisions about the protection of these birds. The surveys have already documented changes in bird behavior and population levels that coincide with years of steadily warmer temperatures in the park.
Four key recommendations
Glennon started surveying lowland boreal birds for the New York State Department of Environmental Conservation (DEC) in 2007. At the time, she was the science director at the Wildlife Conservation Society’s Adirondack office, which closed in 2018d. The state-funded survey aimed to assess the status and distribution of what were initially a dozen species, with data for a 13th species, the Canada warbler, added more recently to the survey. The target species include less-familiar birds such as the three-toed and black-backed woodpeckers, but also more commonly known species such as the Lincoln’s sparrow, the yellow-bellied flycatcher (see page 67), the boreal chickadee and the gray jay. Glennon submitted a preliminary report on her findings in 2009, and a full analysis in 2017. This March, she filed an updated report to the DEC with four recommendations on best management practices for these birds.
What she has seen over the years is a decline of many lowland boreal birds—likely the result of changing temperatures and precipitation patterns; an apparent northward or upslope movement for some species; and an especially notable decline of birds from smaller, more isolated wetlands near roads and other areas of human encroachment. There are many such places where wilderness and human activity run close to each other even in the Adirondacks, one of the most protected natural areas in the country.
Peatlands—wetlands such as bogs and fens—are becoming especially important to boreal birds, Glennon has found, because peatlands tend to be cooler than surrounding habitat and may serve as temporary refuges for birds as they begin to move farther north, or higher up a mountain, to escape a warmer climate.
“When we started this, climate change was not the real focus of this work,” Glennon said. “It was to see what was in the habitats. Over time, we were seeing somewhat of a pattern for some species, of a northern latitude shift. So we started asking questions over time: Are we seeing a latitudinal shift, or an elevational shift?”
Based on a growing awareness of the importance of boreal wetlands, she recommends: Use ecologically sensitive design approaches for new development; consider how human actions such as the building of ditches will affect water quality and flow; encourage bird-sensitive practices on private land, such as minimizing outdoor lighting (see page 28) and reducing the use of pesticides; and create broader public understanding of the value of boreal wetlands, including peatlands.
Many major peatlands in the Adirondack Park are protected, and that’s laudable, Glennon said, but it’s important to also think small.
“There are these little spots that are all over the Adirondacks,” she said. “They all have a carbon storage function.”
DEC Wildlife Biologist Ashley Meyer said that projects like Glennon’s that track changes in distribution and abundance add valuable information about lowland boreal birds and their habitats. Meyer said it helps inform land use management and conservation efforts to “protect these Species of Greatest Conservation Need from the threat of climate change.”
Mountain migration trends
Ornithologist Kenneth Able spent his career at the State University of New York at Albany, where he became one of the world’s experts on bird migration. While running the university’s research station at Cranberry Lake for several summers in the mid-1970s, he decided to examine the nesting habitats of migratory songbirds. No one was talking about climate change in the 1970s; Able thinks the first time he heard it mentioned was around 1988.
Able and his graduate student Barry Noon surveyed what bird species were breeding at different elevations on the slopes of four northeastern mountains, including Whiteface. They found that different species selected specific elevations as their summer habitat. For all the simplicity of this study, no one had ever done a formal survey of what birds nested at different points in a temperate mountain setting.
The journal Oecologia published their paper in 1976. Able and Noon divided their hand-written data sets, and both kept their copies. Able retired in 2004, and nearly a decade later received an email from Kirchman, who asked if Able still had his data, and could he get a copy of it?
The paper based on that data—which Kirchman produced with Alison Van Keuren, a volunteer in the museum’s ornithology collection—demonstrated that many of the birds on Whiteface surveyed by Able and Noon had started to nest higher up the mountain, a shift that occurred as temperatures in the region steadily rose. In fact, Kirchman and Van Keuren found nearly twice the number of species at the summit of Whiteface than Able and Noon, 13 as opposed to seven. The Wilson Journal of Ornithology published the findings in 2017.
Biologists are cautious about making sweeping statements about climate change, and Kirchman has noted that many factors can affect bird populations. But given that Kirchman and Van Keuren also noted that the average daily minimum and average daily maximum temperatures for the summer breeding season in that part of the Adirondacks had risen since 1974, by 4.43 degrees and 3.38 degrees respectively, the upward movement of birds on the Whiteface slope was hardly a shock.
In a recent interview in Kirchman’s laboratory at the state museum (where Kirchman displays a large illustration of the American three-toed woodpecker, reproduced from a painting by the famous bird artist Louis Agassiz Fuertes in the early 1900s), Kirchman said that his survey and Glennon’s work are especially important because they capture mostly different groups of birds. While there is some overlap in the species both have documented—the yellow-bellied flycatcher, for example is in both surveys—many of the birds are found either at higher elevations or the lowland boreal habitat, but not both.
Until Glennon started her survey, Kirchman noted, “No one was looking at the bogs.”
Their work also comes from different scientific perspectives: Glennon is an ecologist, interested in plant communities in habitat; Kirchman is an evolutionist, interested in how birds evolve to adapt to different conditions.
As further proof of his caution about making blanket statements on his findings, Kirchman cites one well-regarded paper that came out three years before his that showed some high-elevation birds in the White Mountains starting to move farther down mountain slopes. Not what you would expect at first, but the authors of that study—William DeLuca and David King—noted that there may be a climate link even in that behavior. Increased precipitation with warmer temperatures might make some birds move farther down an exposed mountain slope to the more heavily forested lower sites for a reason that makes perfect sense: They want to get out of the rain.
“With some birds, their niche is defined by moisture, more than temperature,” Kirchman said.
Continuing uphill and downhill watch
Kirchman went back to Whiteface to repeat the survey in 2021 and 2022. He found no significant changes from his original findings, but he plans return survey trips to Whiteface every five to 10 years. He sees the survey as a continuation of the baseline research done by Able and Noon of now a half-century ago—a remarkably simple but pioneering idea that has taken on new meaning with the intervening decades.
“I always thought I needed to keep that data set going,” Kirchman said.
Glennon, too, plans to continue her lowland survey. She kept it going long after the original state grant ran out, through a patchwork of state, federal and private funds. She is glad that she did, because it took years to begin to see patterns, such as peatlands serving as temporary refuges, that she could never have predicted at the beginning of this work.
She’s also seen several of the species she has been following become much scarcer in the Adirondacks since starting the survey in 2007, including the black-backed woodpecker, the boreal chickadee, the Lincoln’s sparrow, the olive-sided flycatcher, the rusty blackbird and the yellow-bellied flycatcher—and of course, the American three-toed woodpecker, which may now be gone entirely from the park. In a biologist’s terminology, that bird may be extirpated—not extinct, but vanished from a former habitat.
“It is depressing to work on this for so long and see these declines,” Glennon said. “But there are some species that are hanging on, so I’m not entirely without hope.”
The message that she wants to convey through her survey: Regardless of the size of a lower-elevation boreal wetland “It all matters. It’s all important.”