Yellowstone biologist takes birds under his wing

There are flecks of gold that flutter into Yellowstone National Park each spring.

The tiny Wilson’s warbler, with its bright yellow feathers, weighs less than half an ounce with a wingspan stretching only 6 inches. A bug-eating bird, it is fond of dense stands of willow in mountain meadows.

These small songbirds, and others like them, are likely to go unnoticed by the thousands of tourists more interested in spotting bison, elk, wolves and bears. Yet the park’s diverse population of feathered creatures are of interest to scientists like Yellowstone wildlife biologist David Haines who are attempting to understand ecological and environmental changes in the popular park.

Songbirds are also of worldwide interest because of the continued decline in their populations. Since the 1970s, scientists estimate songbird numbers have declined by 3 billion birds. The most endangered are those living in grasslands and sagebrush steppe communities.

Interest in the park’s bird community dates back to counts done as early as 1872, when Yellowstone was designated a national park.

Although some of the species seen in the park may be spotted in a backyard, the Yellowstone environment presents unique conditions and challenges the birds might not be experiencing anywhere else, Haines said. He pointed to a book published last year, “Yellowstone’s birds: Diversity and abundance in the world’s first national park,” as one way to educate the public about the park’s birds, their natural history and science that’s been conducted in the park.

“It puts it in a way that everybody can wrap their heads around and raise awareness of them in the park,” he said.

Bird bio

Haines is Yellowstone’s lone biologist dedicated to birds, a position he was hired to fill after wolf biologist Doug Smith retired in 2022. Smith had volunteered to keep the bird program alive when the position went vacant years earlier.

“The bird program was left in a much better state historically,” Haines said. “We were doing way more than prior to 2008. It was an even smaller program then. Now we’ve been able to bring a good amount of soft money into this program.”

In the summer, two to three bird technicians are hired for seasonal work to help, along with volunteers. Several universities have also deployed researchers to study species like ravens and Clark’s nutcrackers.

Haines worked under Smith as a graduate student studying raptors in Yellowstone. It was an interest Haines came to indirectly. While pursuing a degree in botany he took an ornithology class that captured his attention.

Luckily, botany is a foundation for many of the habitats where birds are found, so Haines’ other science background is still of great use.

Bird abundance

About 150 different species of birds nest inside the park while studies have documented almost as many that pass through. Two-thirds leave when winter arrives.

The majority of the resident nesters are songbirds and woodpeckers. Other species include waterfowl, shorebirds and 19 different raptors, four of which are owls.

Despite the strong songbird numbers, Yellowstone’s bird populations have faced a variety of challenges over the years.

Ospreys disappeared from Yellowstone Lake when cutthroat trout populations plummeted as introduced lake trout ate the native fish. Because lake trout live deeper in the water column, they weren’t available for osprey to dine on. Back in the 1980s there were 70 to 80 breeding pairs of osprey that nested around Yellowstone Lake. Since about 2005 there haven’t been any.

Caspian terns and California gulls disappeared from Molly’s Island in Yellowstone Lake, and the number of American white pelicans and double-crested cormorants nesting on the island have declined. Terns and gulls are surface feeders.

“In this situation, I think birds were maybe one of the most heavily impacted terrestrial species by this change in fish species in Yellowstone Lake,” Haines said.

Trumpeter swan numbers have rebounded from historic lows of only three to four breeding pairs in 2011 to about 30, thanks to increased management including reintroductions of cygnets. The park’s data on swans dates back more than 90 years. Why have their numbers declined?

“Maybe Yellowstone just doesn’t have a lot of good area left for swans anymore,” Haines said of a study looking at habitat he’d like to launch.

The park has a species of common loons that is at the most southern extent of its range. The population is small, only about 25 breeding pairs. Their low numbers are believed to be due to disturbance while nesting. As a result, land managers have implemented closures to see if their numbers increase.

Although research by Haines and Smith showed a dense population of golden eagles mostly in northern Yellowstone, their reproduction rate is lower than birds outside the park. It’s research Haines helped conduct for 14 years.

“So from that standpoint, the golden eagle holds a pretty special place for me in Yellowstone,” he said.

Peregrine falcons are declining in parts of North America and Europe prompting concerns. Haines said it could be tied to repeated outbreaks of avian flu, which is easily spread by migrating waterfowl and can be deadly, not only to infected birds, but possibly raptors like peregrines that feed on sick birds.

“I see high variability from year to year, but I’m not seeing any kind of trend to say that our birds are decreasing,” Haines said. “But if it is something like avian flu, these impacts could happen really quick because in a given year a lot of birds can die.”

The steady decline in whitebark pine, a high-elevation species, could have a similar effect on Clark’s nutcrackers. The birds harvest the tree’s high-protein nuts and cache thousands of them for later meals. This is how the trees disperse. The caches are also a prime target of grizzly bears seeking a meal.

“So those trees aren’t going to move and reproduce without that (bird) species,” Haines said.

Looking ahead

Given the breadth of Yellowstone bird species, Haines has been busy staying on top of the many research projects, capturing and banding work.

The latest research includes examining how grassland birds are doing as bison populations have increased. Although the species have lived side-by-side for millenia, changes in the landscape such as invasives like cheatgrass and other weeds have the potential to alter the relationship.

“There are not many species that are going to show more rapid responses to changing conditions than birds,” Haines said, the literal canaries in the coal mine as ecological indicators of ecosystem health.

The park is also looking at mature forests in the park, which have declined. Little information has been collected on birds inhabiting these regions.

Haines said the bird program continues to examine the relationship between birds and carnivores like cougars and wolves. For example, how golden eagles that remain through the winter benefit from the predators’ winter kills.

“So we’re able to do some really cool stuff that we would never have been able to do prior to this because the funds weren’t there,” Haines explained.

Research has also been done on Yellowstone ravens, showing their connection to wolves as well as human resources like the Gardiner wastewater treatment plant.

For all of this monitoring, nonprofit funding and graduate studies are key, Haines noted.

Looking ahead, he’d like to have more intensive surveys of Yellowstone Lake’s bird populations, seeing that as a gap in the park’s knowledge base.

“I think people knowing that there’s active research happening in relationship to questions regarding overall populations and the health of birds in Yellowstone is important,” Haines said. “Through our monitoring and collaboration we’re trying to keep an eye on the pulse of all this.

“It’s a small effort for a big place.”