Avian census reflects climate change

Rare visitors to Montana, a pair of Pacific loons bobbed along in the gentle swells of Flathead Lake on a chilly morning Dec. 19.

About 1,000 feet from the shore, the vivid black-and-white stripes along the birds’ backs and necks would appear momentarily in Craig Hohenberger’s spotting scope, then vanish behind another wave.

“They’re more of a fall bird,” Hohenberger, a retired ornithologist, explained, automatically adding “golden-crowned kinglet” as he picked up the barely audible call from an unseen bird. “It’s normally around October you might see them.”

If you’re within a few miles of the Pacific Coast, that is, where the birds typically spend their winters between trips to their breeding grounds in Alaska and northern Canada.

It was an exciting find to kick off the Audubon Society’s Bigfork Christmas Bird Count, a local effort that for 41 years has contributed to the longest-running citizen science project in the nation.

Ornithologist and Audubon officer Frank M. Chapman started the holiday birding tradition in 1900. Now for more than a century, the national conservation group has been growing a vast data set of year-to-year changes in bird abundance and migration patterns.

From mid-December through early January each year, Montana’s 33 regional bird counts harness the volunteer efforts of nearly 1,000 birders — from retired ornithologists to amateur wildlife watchers.

In Bigfork, the annual count covers a geographic circle 15 miles in diameter — about 177 square miles. Yet on a single day in December, the 30 or so locals that gather for the daylong event may identify as many as 90 distinct species.

Bigfork was the first in Montana to reach that milepost, although its annual total has been overtaken by the Stevensville and Missoula counts in some recent years. Since 1975, 150 species have been identified during the Bigfork counts.

This year, Audubon volunteer Steve Walker hiked through slowly melting snow on the nearly 2,000-acre waterfowl production area that lines Flathead Lake’s northern shore. He pointed to thick clumps of willows along the edge of the lake.

“The short-eared owls like to get into the brush there, where the great horned owls can’t get them,” he explained. Along a low ridge, one of the aforementioned predators kept watch from its high perch in a birch tree.

Walker, Hohenberger and Steve Gniadek (a retired Glacier and Yellowstone park biologist) made up one of the small groups of volunteers hiking and driving through each of the count circle’s 10 subsections. The groups recorded a combined 81 species, including spotted towhee, western meadowlark, American kestrel and a gray-crowned rosy-finch.

The range of habitats within the area creates an impressive level of biodiversity, said Hohenberger, borne out by the number of bird species the Bigfork volunteers tally each December.

“We have both coniferous and deciduous forests. We have open grasslands, which are very good, and a lot of open water most years,” he said. “We also have a fair amount of residential areas that are attractive because of berries and bird feeders.”

That human development can come at a cost to other birds, however. To Hohenberger, the trends illustrated by the bird count totals underscore the importance of habitat conservation in the Flathead Valley. The “old-timers” estimate the number of birds in the valley has dropped by half since the 1960s, he said.

“It’s part of the whole continuum. You take one thing out of the ecosystem and it affects everything else, like a domino effect. You start losing birds, and it can cause an explosion in insects and lead to many other problems.”

Montana Audubon’s senior policy director, Janet Ellis, said the impressive collection of data points has tracked robins, American crows and redheads (the ducks) appearing farther and farther north during this time of year. Historically the onset of winter used to push them south earlier.

“Climate change is perhaps the most recent use of [the data],” Ellis said. “In past Christmas bird counts for Bigfork, they’ve documented some winter range shifts north as it gets warmer.”

Audubon’s research has shown that since 1900, those ranges have crept significantly northward: American crows by 89 miles, mourning doves by 147 miles and American goldfinches by 219 miles.

And even the short-term changes can provide clues about the ecosystems the birds inhabit.

“Common redpolls, I think there’s something going on with whatever food source is north in Canada,” she said. “They’re actually moving farther south this year.”

The bird counts can also reveal the expanding range of invasive species such as Asian collared doves, released on the North American continent in the 1950s. It wasn’t until after 2000 that the first ones showed up in Montana. Now they are spotted every year during Montana’s bird count, including in Bigfork.

But the recent presence of a pair of Pacific loons — representing half of the total in the Bigfork count’s 41 years — is less clear at this point.

“It’s hard to say,” Hohenberger said after the count. “I think it’s a random event. But if in the next couple years we start getting them, you might think, four or five years, that’s a trend. With climate change we’re starting to see certain patterns, but it takes a long time.”

Audubon, like other conservation organizations, is concerned about the impacts climate change will have on the natural world. Some climate scientists predict that many species will go extinct as the changes outpace their ability to adapt. Others could flourish or establish themselves elsewhere.

And yet there’s something of a silver lining for those who relish the chance to identify a new bird species entering a region for the first time.

“As a birder, you can look at it as more or less pretty exciting as birds move farther north,” Hohenberger said. “It’s going to be a changing landscape for years to come. But as a birding sport, it adds a lot of new things and dynamic trends that are happening.”

Reporter Sam Wilson can be reached at 758-4407 or by email at swilson@dailyinterlake.com.