Boreal birds declining in the Adirondacks

SARANAC LAKE – Recent surveys by the Wildlife Conservancy Society have found that populations of several boreal birds are declining in Adirondack lowland wetlands.

The data comes from studies being done by WCS Science Director Michale Glennon, who is based in WCS’s Saranac Lake office and has been collecting information about boreal bird populations in Adirondack wetlands since 2003.

Glennon recently had her study, “Dynamics of Boreal Birds at the Edge of Their Range in the Adirondack Park, N.Y.,” published in the Northeastern Naturalist journal. This paper used data collected during the five-year period between 2007-2011.

It found that three species warranted attention in the Adirondacks: boreal chickadee, olive-sided flycatcher and rusty blackbird. The paper said all three “showed high extinction probabilities in Adirondack wetlands, and boreal chickadee and olive-sided flycatcher appear to demonstrate declining trends in New York as well as on some larger scales.”

When Glennon added data collected since 2011, she found that the number of wetlands occupied by the rusty blackbird, gray jay, yellow-bellied flycatcher, olive-sided flycatcher and black-backed woodpecker had declined by 15 percent or more since 2007.

Of the eight birds surveyed, only the yellow palm warbler’s population was found to be increasing. The other bird studied was the Lincoln’s sparrow, which was found to have an increasing population between 2007 and 2011. However, more recent data indicate the bird’s population is also declining in Adirondack wetlands.

These birds are important, not only to the ecology of the Adirondack Park but also the tourism economy. Many of these boreal birds are found only in the Adirondacks and draw attention from bird watchers from all over.

“You don’t find them once you get out of here,” Glennon said. “They’re not in the Southern Tier. They’re not in the Catskills.”

The bird data was collected from lower elevation wetlands throughout the Adirondack Park. Larger wetlands surveyed included places such as the Massawepie Mire west of Tupper Lake and the Osgood River, north of Paul Smiths. Other places looked at include Hitchens Bog, Jones Pond Outlet and the Silver Lake Bog.

For these boreal bird species, the Adirondack Park represents their southern range in eastern North America. The birds prefer habitats that are cool and wet, such as sphagnum-draped bogs and swampy woods. These habitats are thought to be vulnerable to climate change, particularly in the Adirondacks where they are more fragmented than in forests to the north, according to WCS.

The larger bogs such as Massawepie act as source habitats and are where the birds produce a lot of young, Glennon said. Some birds will then leave those source habitats for small, isolated wetlands that are common in the Park.

“Birds are kind of reliant on both places because you can’t fit everybody in the sources,” Glennon said. “Most wetlands are not really big, so from a numbers standpoint, most of your individuals are actually going to be in those littler places.”

Glennon found that the location and connectedness of their wetland habitats were important, as was nearby human infrastructure, with birds much more likely to disappear from smaller, isolated wetlands that are near development.

“The human infrastructure question is interesting because none of these plots we are in are particularly close to development, but obviously it’s close enough to have some influence on them,” Glennon said.

She said it’s important for land-use planners to keep this in mind, and also that many of these wetland habitats are linked, not only for boreal birds. Spruce grouse, moose and marten are examples of other animals that use these lowland boreal wetlands and travel between them.

“If we can maintain some of the connections of those habitats and try to buffer those wetlands and keep disturbance out of them, I think that can help maintain this larger network of population,” she said.

Glennon also looked at whether the birds appear to be shifting to higher latitudes and elevations, a pattern documented for many species responding to climate change around the globe. The analysis yielded inconsistent results, with some birds moving northward or upward and some not. This suggests that over this small window of time, other factors may play a larger role in controlling these species’ dynamics, according to Glennon.

“I think that climate change is probably impacting them, but it’s acting together with other factors, like development or recreation,” Glennon said. “If they were in boreal Canada, where they had miles and miles and miles of this habitat, where it’s all big and connected, a lot of it, that’s a very different scenario than birds that are trying to make it in little fringy patches of boreal that we have down here. We are totally intermixed with your traditional hardwood forest, which isn’t really their habitat. So I think no matter what, they’re going to face a tough time, and I think over the long term, we will probably see range contraction. If we’re not seeing it already, we’ll probably see it for a lot of these species.”

The research for this study was funded by the New York State Department of Environmental Conservation State Wildlife Grants Program, the Northern New York Audubon Joseph and Joan Cullman Foundation Grants Program and others.