Study paints bleak picture for area's birds

Some of Glacier National Park’s iconic birds could see drastic reductions in summer and winter range, according to climate change modeling recently completed by the National Audubon Society.

The Park is home to 25 percent of the Montana’s nesting common loon population, but the Audubon study claims that by 2080 loons will lose 56 percent of their summer range and 75 percent of their current winter range.

The American dipper, a common species in Glacier Park that feeds and lives almost exclusively along the Park’s free-flowing and frigid streams, could lose 88 percent of its summer range, according to the modeling.

Audubon scientists used three decades of citizen observations from the Audubon Christmas Bird Count and the North American Breeding Bird Survey to define the “climatic suitability” for each bird species — the range of temperatures, precipitation and seasonal changes each species needs to survive.

Then, using internationally recognized greenhouse gas emissions scenarios, they mapped where each bird specie’s ideal climatic range might be found in the future as climate changes.

Of the 588 North American bird species studied, more than half are likely to be in trouble, about 314 species, of which about 233 species call Montana home.

“Many of our forest birds, such as the western tanager and Clark’s nutcracker, will not have the climate and associated habitats they need here in Montana and will need to search for new places to live, if we don’t take action,” said Amy Cilimburg, Montana Audubon’s director of bird conservation and climate policy. “This is a wake-up call. We all share this challenge, let’s find solutions together.”

While it looks at climate suitability, the study does not actually model a key factor in bird survival — habitat — and other parts of the study are still under peer review.

A sharp decline in Clark’s nutcrackers is already taking place in Glacier Park as one of their primary food sources, whitebark pines, have died from blister rust and beetle infestations. Clark’s nutcrackers were once considered common in the Park.

Cilimburg cautioned that the report is “our best assessment,” and that the modeling was “not an exact science.” But warming climates certainly will have an impact on forests, streams, wetlands and grasslands.

Several large wildfires have impacted the Park over the past decade, scorching more than 10 percent of the Park. While those forests are regenerating, it takes decades for them to produce food sources like cones and seeds for many bird species.

The evening grosbeak, for example, is listed as a common species in Glacier’s official bird list, yet one would be hard-pressed to find one in the Park on most days.

The worry, Cilimburg noted, is that climate change won’t simply be a slow warming process — it could also bring wide climate variables for two or three breeding seasons that some species might not be able to tolerate.

“Some small bird populations could get whacked down fast and have a hard time coming back,” she said.

For its part, Glacier Park should do more monitoring, Park biologist Lisa Bate said. The Park is already keeping a close eye on common loon populations through an extensive citizen-science network. The Park also tracks harlequin ducks, has started a fall raptor monitoring program and conducts two breeding bird surveys in summertime.

But bird surveys are inexpensive and effective, Bate noted, and more breeding bird surveys could be done. Citizens with some training could conduct breeding bird surveys in alpine areas, where there are fewer bird species, she said.

Park crews conducting harlequin duck surveys in spring are already keeping track of dippers and other waterfowl, Bate said.

While some bird populations are declining, others are expanding. Barred owls are becoming more common across the West, and northern hawk owls have bred in Glacier Park over the past 10 years, taking advantage of terrain east and west of the Continental Divide opened up by recent fires. Northern hawk owls generally nest in Canada and Alaska, and Glacier Park is the southern extent of their range.