Mention Yellowstone National Park, and golden eagles are not a species likely to spring to mind like bison, elk, wolves or bears.
Doug Smith is hoping to change that perception.
“Yellowstone is a large-mammal park, so there’s not the money invested into bird (research),” said Smith, Yellowstone’s senior wildlife biologist. “We’re trying to build birds up to the level they deserve.”
For five years, Smith led the Yellowstone Raptor Initiative, a study designed to collect baseline data on golden eagles, red-tailed hawks and Swainson’s hawks, with a lesser focus on American kestrels, prairie falcons and owls. That study ended last year.
This year Smith cobbled together funding to enable wildlife biologist Dave Haines and an intern to intensively examine golden eagles, a predator species whose stronghold is the western United States, including a talon-hold in the Northern Range of Yellowstone.
Considering the mountain habitat and high elevation of Yellowstone’s Northern Range, the region would appear to be marginal golden eagle habitat. They are more at home in the desert, grasslands or tundra — areas with wide swaths of open ground inhabited by rabbits, marmots, ground squirrels and other small mammals.
Yet the raptor initiative found 28 golden eagle territories, the majority of them in the Northern Range — which is the area roughly between the North and Northeast entrances to Yellowstone.
“We didn’t think there were six to eight parkwide, so that by itself is really huge,” Smith said. “We were really wrong.”
The park’s previous bird biologist retired in 2007. To save money, no one was hired after that. And golden eagles were never a studied species in the park, with emphasis instead given to monitoring peregrine falcons, osprey and bald eagles.
In addition to being prime territory for golden eagles, the Northern Range is the premier region for gray wolves in Yellowstone, home to the majority of the park’s packs.
The link between the two very different predator species may be elk. The Northern Range once held a population of almost 20,000 elk before wolves were reintroduced in 1995. Following wolf restoration, the elk population steadily declined before rebounding to about 4,000 last year.
Since golden eagles are a long-lived species — up to 30 years — Smith theorizes that their population may have grown so dense in Yellowstone thanks to the availability of elk that died during the park’s harsh winters prior to 1995, providing a carcass food source. With wolves’ return to the landscape, the big canines started accounting for more elk deaths in the park. Smith’s wolf staff has documented golden eagles — along with a variety of other predators like coyotes, foxes and bears — feeding on those wolf-killed elk.
“Now most carcasses are derived from carnivores,” Smith said.
Robust populations of golden eagles are typically associated with a strong prey base that allows the big birds to concentrate on that one mammal. But surveys of golden eagle nests has shown they are generalists in Yellowstone, eating everything from pronghorn and deer fawns to bluebirds and owls.
Although this year’s study of golden eagles was put together on a shoestring budget, Smith is hoping to extend the work for at least one more season.
“Golden eagles need to be on the lips and minds of visitors,” just like other wildlife in Yellowstone, Smith said. “If people know about them, conservation follows. If people don’t know about them, nobody cares. It’s a big thing for me. I cut my teeth on wolves, and now birds are part of my job.”