JACKSON, Wyo. — Despite the high elevation, harsh climate, vast lodgepole pine forests and short growing season, Yellowstone National Park (YNP) provides great habitat for a large diversity of birds.
Douglas Smith, former wildlife biologist for YNP known for his work with wolves, was assigned to study birds in the park in 2008. While some species like golden eagles and peregrine falcons are built to deal with harsh conditions, Smith admits that even he thought the national park might not be the best home for many avian species.
“It does look like bad habitat,” Smith tells Buckrail. “But you take a closer look and there are a lot of pockets of great habitat for birds, and lots of bird diversity. It really attests to the value of saving [YNP] and protecting it.”
Smith points in particular to thermal basins, which don’t have year-round snow due to their heat. These thermal areas are able to welcome early migrating birds who can find food there in a landscape otherwise covered with snow. Extensive wetland areas also provide homes for swans, loons, ducks and geese; Heart Lake, where a warmer creek flows in and thermally insulates a big area of open water, offers loons a place to wait for other areas in the park to thaw and open back up.
Smith also says that beaver-created wetlands and pockets of high-elevation aspens provide high-quality habitat for songbirds. While “generalists,” as Smith calls species like eagles, ducks, geese and swans, are adapted to living across broad landscapes in a highly variable environment, the more sensitive songbird species are critical to the ecosystem as environmental indicators.
The U.S. Environmental Protection Agency defines an environmental indicator as a measure of the condition of a landscape or ecology. According to Smith, songbird status gives insight into the health of the Greater Yellowstone Ecosystem (GYE) because songbirds have very specific habitat requirements. Wilson’s warblers are almost entirely dependent on high-elevation willow. Brewer’s sparrows are tied to sagebrush, and kestrels are tied to the cavities that aspen stands provide.
“If that one thing goes out, they go out,” Smith says in the case of species-dependent songbirds. “They’re very sensitive to small changes.”
Songbirds also rely on insects, and Smith says a lot of migrations are finely tuned to when insect populations peak in the spring. Songbirds have evolved over thousands of years to time their migration arrivals in the GYE with the periods when insects become super abundant. However, Smith says these previously selected migration times are currently misaligning with the timing of insect flushes.
This is particularly problematic for Neotropical migratory birds, which the U.S. Forest Service classifies as bird species that migrate south of the continental U.S. for winter and back up to North American temperate zones for breeding. According to Smith, these species are genetically programmed to migrate at a previously selected time, meaning some arrive every year within two to three days of their arrival date the previous year. Because of this evolutionary programming, these birds aren’t able to monitor insect conditions in the GYE like local migrants can or adjust to meet a spring insect peak if it’s early.
But songbirds can also indicate when more positive changes are taking place. During Smith’s career in Yellowstone, he says he witnessed Wilson’s warblers coming back in response to the recovery of willows after being over-browsed by elk.
Based on his research, Smith says that birds emphasize the need to take a hard look at the GYE and shape more cohesive, broad-scale habitat conservation. Smith’s new book, Yellowstone’s Birds, is the first in YNP’s history to explore the interdisciplinary topics of avian natural history, ecology and conservation.
