This pine needle-eating bird is disappearing from Adirondack forests

In the pitch black of night, biologists Angelena Ross and Glenn Johnson pack up their things, load cargo into their truck, and leave their campsite in the gathering darkness of a Canadian forest. They plan on driving through the night, stopping only for coffee at a Tim Horton’s along the way, in order to reach the U.S. border by morning. It’s important that they do, because Ross and Johnson aren’t traveling with just any cargo. Inside their truck is a load of live birds, carefully packed in boxes and headed for New York State’s Adirondack Mountains.

“It’s something I never thought I would do,” Ross recalls of the 2019 trip. She’s always loved studying wildlife, but taking care of birds on the road is new to her. This road trip is the only way to get these chicken-like spruce grouse to New York’s boreal forests. Ross, a biologist at the New York State Department of Environmental Conversation (DEC), and Johnson, a biologist at the State University of New York at Potsdam, are moving the birds in an effort to help repopulate spruce grouse in the Adirondacks.

“They’re really on the brink,” says Jeremy Kirchman, curator of birds at the New York State Museum and the first author of a January 2020 study that showed Adirondack spruce grouse are not only rare, their populations also seriously lack genetic diversity. Without interventions like importing live birds from Canada, he says, spruce grouse would likely go extinct in New York State.

Spruce grouse aren’t only declining in the Adirondacks. Although the species is doing relatively well worldwide, there are early signs that spruce grouse may be in trouble in some other states, like Maine and Minnesota. This decline is another warning sign that wildlife in northern U.S. forests are facing increasing challenges from isolated habitats, human development, and even climate change, researchers like Kirchman say. 

That is how biologists Johnson and Ross found themselves ferrying spruce grouse to the U.S. from Canada, where the birds are still fairly common. They started the repopulation project in 2013, but the root of the problem goes back over a century, when heavy logging in the Adirondacks transformed the landscape. Many forests have grown back since then; a 2018 study found that forests worldwide have actually expanded over the past 35 years. Even so, formerly continuous forests like the Adirondacks are now divided up by roads, says Kirchman, making it hard for animals like spruce grouse to move around safely.

“Things quit going the way of the spruce grouse when the people showed up,” says Kirchman. “They end up dead on roads.”

Spruce grouse are very particular about their habitat. They need brush and berry bushes near the ground, but also abundant trees with needles, called conifers, says Glenn Johnson. Young forests lack the necessary heights, old forests lack the bushes. The ideal habitat is in the transitional years between a forest’s youth and its old age. 

“They need sort of the middle ground,” Johnson says, when peatlands, a type of forest marsh, are present. The fact that these habitats are so transient is part of the reason why spruce grouse populations are struggling in the Adirondacks and elsewhere in the northern U.S., according to Johnson. 

But the natural progression of the landscape is not the whole story in the Adirondacks. In the late 1800s, long before the Adirondacks were a protected area, loggers started clear-cutting large areas of the forest for timber. They used local rivers to transport all this wood, creating dams and flooding areas of the forest in the process.

“They drowned out a lot of these big peatlands,” says Johnson. Spruce grouse don’t do well in open marshes, he says. They’ve been declining ever since.

The habitat loss also means that spruce grouse populations are fragmented — the Adirondack birds are separated from spruce grouse farther north in the U.S. and Canada by open areas and unsuitable forests.

The Adirondacks are “basically a habitat island,” he says. With the spruce grouse population being so isolated, it would be reasonable to assume they lacked genetic diversity, like birds he’s studied on actual islands. With this in mind, he wanted to know just how dramatically genetic diversity had declined in Adirondack spruce grouse. Luckily, Ross and Johnson were already asking themselves the same thing. 

They had been surveying the spruce grouse population since 2002, collecting blood samples and mouth swabs from birds in the hopes of one day doing genetic work. When Johnson met Kirchman and told him about his surveying work, Kirchman decided to take the genetic data that Johnson and Ross had collected in the Adirondacks and compare it to genetic samples from spruce grouse specimens in the State Museum and in 18 museums across the northeast.

The lack of genetic diversity was even more striking than what he had predicted. Kirchman found that the Adirondack birds were less genetically diverse than even some species that have gone extinct, including the heath hen, a type of grouse that used to live on Martha’s Vineyard, an island off the coast of Massachusetts. The spruce grouse’s genetic diversity had decreased three fold in a little over a century. This kind of poor genetic diversity can mean a species is less likely to adapt to changes in their environment, making them even more vulnerable, according to Kirchman. 

Early genetic results were compelling enough that in 2013, years before the study was completed, Ross and Johnson started their repopulation efforts, although more as a test than anything else, according to Ross. Ross says that this first year, they only brought back three adult birds from Canada. That number has increased every year since, she says. 

Although Johnson and Ross have relocated some spruce grouse from the woods of northern Maine, some signs indicate the population might be declining there as well. On Maine’s Mount Desert Island, home of Acadia National Park, the spruce grouse population seems to have recently dropped dramatically. In 2018, Erik Blomberg, an ecologist at the University of Maine, and graduate student Christopher Gilbert conducted a replica of a survey done 25 years ago. They found that fewer than half of the areas previously surveyed still had birds in them. Blomberg says that in many ways, this population in Maine is similar to spruce grouse in the Adirondacks.

“Here in Maine, we are working with a literal island,” says Blomberg, with his population facing many of the same isolation problems as the “habitat island” in the Adirondacks.

Blomberg also says he thinks that the shrinking spruce grouse population on Mount Desert Island could be an indication of broader species decline in Maine. He says that some of his current research, which has not yet been published, shows that spruce grouse in northern Maine are having a hard time surviving. He says he thinks this is due to a combination of factors, including the commercial forestry industry in Maine, which has reduced the prevalence of the coniferous trees that spruce grouse depend on. 

In Minnesota, meanwhile, spruce grouse are still abundant enough that they can be hunted legally. Yet no one knows the exact number of birds or how the population has changed over time, says Charlotte Roy, a biologist at the Minnesota Department of Natural Resources. She recently started a survey project, recruiting area volunteers to help. She says that although it will take more time to know for sure, Minnesota grouse don’t appear to be struggling as much as in the Adirondacks or on Mount Desert Island because Minnesota has more areas of uninterrupted forest. But even in Minnesota, she says, there is some early evidence that the population is beginning to shift north.

“Some animals will be able to adapt and move, and others won’t,” Roy says. “Those that don’t will no longer be around.” With poor genetic diversity in some populations — like the one in the Adirondacks — and reliance on specific habitats, spruce grouse may not be able to handle these changes, which are affected by climate change as well as deforestation, Kirchman says.

Blomberg agrees. “There’s some reason to think that spruce grouse could be a pretty good ‘canary in the coal mine’ in that regard,” he says. Because they depend entirely on the forest and live there year-round, the health of their species is closely tied to the health of the forest, he explains.

Meanwhile, Johnson and Ross continue to go on their repopulation trips, which seem to be paying off. According to a recent update on the recovery plan, about half of the 105 total birds they released in 2018 survived until 2019, which is only slightly below average for the area’s native spruce grouse. But researchers like Charlotte Roy point out that to really help spruce grouse, more than just repopulation will be necessary.  

“A lot of the reason they’ve declined is because of habitat loss,” Roy says. “You need to address the habitat loss to recover the population.”

Addressing habitat loss, of course, is part of Ross and Johnson’s recovery project. Ross says she is helping to manage more than 10 patches of spruce grouse habitat, employing methods to limit forest succession. Combined with the repopulation plan, which aims to release at least 250 adult spruce grouse in the next five years, Ross says the recovery project should ensure that there will be spruce grouse in the Adirondacks for the next century. Although the goal of the plan was never to repopulate the entire Adirondacks, it’s been effective so far at establishing a network of spruce grouse communities in the area. 

Spruce grouse feed directly on their forest habitat, Ross says, so it’s crucial to make sure that they still have trees left to eat. “I sincerely think that as long as the forest is there, we will have spruce grouse,” she says. And with her and Johnson ferrying more spruce grouse across the border every year, she can’t help but be optimistic.