Golden eagles are barometers for how to think about landscape changes and threats to wildlife in the West. Featured in new film, Charles Preston says these amazing birds of prey deserve our attention
Striking birds of prey, golden eagles are sensitive to a number of environmental factors. A few years ago, a golden that was part of a research project in Yellowstone died from lead poisoning after ingesting lead ammo. Photo courtesy Wild Excellence Films
by Todd Wilkinson
They hold aloft in the thermals above us as predators, drifting sometimes over hundreds of square miles of open space in a single afternoon, using keen eyesight to hunt and lock in on prey. Some have the aerial maneuverability of Top Gun fighter pilots; others appearing more nonchalant in their slow soaring above rural fields; still others inhabiting spaces closer to our backyards in town, feeding on squirrels, songbirds and pigeons.
While they assume a more subtle profile compared to the “charismatic” terrestrial
megafauna of the Greater Yellowstone Ecosystem, raptors animate the skies and, as barometers for assessing the health of landscapes, Dr. Charles Preston says they are just as important—and extraordinary. One of those species, he says, is the golden eagle.
Some readers here may recall that, back in December 2018, a golden eagle, the first one banded as part of a research project in Yellowstone National Park, was found dead near Phantom Lake in the park. A necropsy determined it died from high levels of lead poisoning caused by ingesting lead ammunition in whatever animal it was eating, perhaps the gut pile of an elk or deer left behind by a hunter outside the park.
Preston says it reminds us how wildlife are affected by issues transcending invisible boundaries we put on maps. Ecosystemwide concerns are his specialty. For years, he served as the founding and senior curator of the Draper Museum of Natural History in Cody, Wyoming—among a complex of five different museums in that small western town located east of Yellowstone National Park and plotted by William F. “Buffalo Bill” Cody. Along with its sister institutions that showcase western and indigenous history, fine art and a world-class firearms collection, the Draper is the most recent addition to the Buffalo Bill Center of the West.
Owed to the iconic region it interprets and celebrates, the Draper has assumed a dynamic yet unsung place in Greater Yellowstone. Opening 20 years ago this summer, the Draper defied skeptics who claimed that museums were passe, that they couldn’t command the interest of young people in an age of fixation on digital technology.
But the Draper has not only proved the naysayers wrong, it has also made meaningful contributions to educating the masses about why Greater Yellowstone is rare and one of a kind in the US. Yes, raptors factor prominently into its appeal.
Preston retired from the museum at the end of 2018 and has had an influential voice, as a conservationist, in thinking about the future of Greater Yellowstone While today he has an emeritus role with the museum, he never stepped away from his passion as a field researcher thoroughly devoted to the study of birds of prey. Under Preston’s leadership, he and colleagues established the Draper Raptor Experience, a hub for educating the public (especially kids) about meat- and fish-eating birds, but it continues to make meaning contributions to their conservation.
The Rohms' film is based on golden eagle research by Chuck Preston focused in the Big Horn Basin and eastern areas of the Greater Yellowstone Ecosystem. It will soon be appearing on PBS stations across the country.
Today, the work of Preston and wife-husband filmmakers Melissa and David Rohm, who own Wild Excellence Films, could not be more timely or urgent. The Rohm’s new documentary, scheduled to air on PBS stations around the country, is titled Golden Eagles: Witnesses to a Changing West. Among the people interviewed is Dr. Shane Doyle, a paleo-archaeologist based in Bozeman, enrolled member of Crow Nation and a board member of Mountain Journal as well as other organizations.
“We wanted to highlight that native people have had a special relationship with wildlife and in particular the golden eagle,” David Rohm says. “As Shane says in the film, ‘The eagles are still here, the medicine is still in this ground and in this air, let’s protect it and keep it here forever.”
Bald eagles may be the national symbol of the country, but goldens are a venerable symbol of the western interior—and, by many accounts, they are in trouble. Beset by ongoing problems of lead poisoning owed to feasting upon carcasses hold lead ammunition, shifting habitat conditions related to climate change, and land use patterns that alter the life histories and abundance of their prey, the plight of golden eagles warrants our attention, Preston says.
The film has been in development since 2017. “Dr. Preston is an extraordinary person. It is a privilege to accompany him in the field. He often tests you with questions about wildlife and asks you to look out over the landscape and ‘indentify the eagle nest’ when traveling to a specific location in the Big Horn Basin, some of those nests are challenging to spot. Chuck is so very patient and wise. People always ask us what is it like to spend time with Chuck in the field. I have a one word answer—depressing! I am being a bit comedic here but his accomplishments in his field are astounding. The amount of educational and life experience knowledge not to mention his advancements in academia are truly off the charts in terms of capabilities for the average person.”
Preston is out front with data reminding us why we should care. It’s fitting that a professional biologist with connections to Greater Yellowstone would be touting science to save a species. Preston follows in a long line of notable field scientists in the region who have—and continue—to carry out landmark research on grizzly bears, wolves, bison, elk, bighorn sheep, moose, pronghorn, mule deer, trumpeter swans, fish, frogs and toads and many others when you also include plants and fire ecology.
Among the venerable names in the Greater Yellowstone pantheon are Olaus and Adolph Murie, John and Frank Craighead, Mary Meagher, Luna Leopold, Harold Picton, and a notable list of others (too many names to mention) carrying on a tradition of ecological study that makes Greater Yellowstone the cradle of American conservation. Without their collective contributions, stewardship of species and landscapes would be running blind. Indeed, a private research organization, Craighead Beringia South, has chronicled the toll that lead ammo has taken on birds and other species.
Mountain Journal had a conversation with Preston. Enjoy it below.
Conservation ecologist Dr. Charles Preston in the field with a golden eagle. Preston played a critical role in establishing the Draper Museum Raptor Experience at the Draper Museum of Natural History in Cody. Not only is the facility connected to research into birds of prey but it advances education by allowing the public to see a variety of different raptor species up close. Photo courtesy Charles Preston
Todd Wilkinson: How did golden eagles assume a prominent place on your personal radar?
DR. CHARLES PRESTON: Golden eagles became a special interest when I was exploring Greater Yellowstone biomes to create Draper Museum exhibits. It was early 2000 when I became aware of rapid landscape changes in Greater Yellowstone and the West. Golden eagles were fairly abundant in the Bighorn Basin but nothing known about nesting status or ecology. It seemed like a great opportunity to gauge effects of changes over long term.
Wilkinson: Where did you find the time because the museum opened during those years?
PRESTON: I was a little busy getting Draper off the ground and getting to know and begin writing and speaking about broad Greater Yellowstone issues. I wasn’t able to find time to dedicate focus on the current ongoing golden eagle study—dubbed the Bighorn Basin Golden Eagle Ecology Program—until 2009 with funding from various sources. About the same time golden eagles became a topic of increasing special concern among state and federal agencies in the West.
Wilkinson: The film is riveting. Tell us about it?
PRESTON: It is about the process and product of our long-term study and how what we’ve learned so far provides insights to conserving golden eagles and other wildlife in Bighorn Basin, Greater Yellowstone and the West.
Wilkinson: Why is it that golden eagles have gotten short shrift compared to their cousins and how is their niche/territory different from bald eagles and where/how does it overlap?
PRESTON: Bald eagles, as a national symbol, enjoy the cachet that comes with that designation. They also received such attention and concern due to their listing under the Endangered Species Act in the wake of severe declines related to use of DDT and other chemicals. That gave them much deserved publicity surrounding that crisis, recovery, and eventual delisting. The bald eagle, too, has a striking appearance with the white head and tail, has a broader range, and is more frequently observed by people across the continent.
Among those interviewed in the documentary is Dr. Shane Doyle of Bozeman. A paleo-archaeologist, Doyle is a member of Crow Nation and he discusses how golden eagles have their own place in indigenous culture. Photo courtesy Wild Excellence Films
Wilkinson: How the niches of both species different?
PRESTON: While similar in size, bald eagles are typically closely associated with large bodies of still or running water. They primarily nest in trees and manmade structures in forested areas— rarely on cliffs when trees are absent. Their diet is dominated by fish and waterfowl, though they will occasionally pirate a prairie dog or other prey from ferruginous hawks or other smaller raptors— and, of course will pirate fish from osprey.
Wilkinson: And goldens?
PRESTON: They inhabit open terrestrial habitats—grasslands, shrublands,and tundra—feeding primarily on rabbits, hares, marmots and other similar sized mammals. Golden eagles are quite versatile hunters and also prey on smaller ground squirrels and are capable of killing mammals the size of deer and pronghorn in certain situations. They are used by falconers in some parts of the world to hunt deer, foxes, and even wolves. In Europe, they also prey on red and black grouse. And, in North America, they will also prey on grouse, chukar, and pheasants, and sage grouse, as ours and other studies have found.
"People always ask us what is it like to spend time with Chuck in the field. I have a one word answer—depressing! I am being a bit comedic here but his accomplishments in his field are astounding. The amount of educational and life experience knowledge not to mention his advancements in academia are truly off the charts." —Filmmaker David Rohm on Dr. Charles Preston
Wilkinson: Why did bald eagles became endangered but golden eagles did not? And why are bald eagles today doing well while golden eagles are confronting threats?
PRESTON: Bald Eagles sit atop an aquatic food chain that includes smaller organisms that ingest chlorinated hydrocarbons (e.g., DDT, DDE), while golden eagles sit atop a terrestrial food chain that does not include significant number of smaller organisms that ingest chlorinated hydrocarbons. Because the chlorinated carbonated pesticides entered aquatic food chains largely from agricultural runoff, they became increasingly concentrated up aquatic food chains. Ingested by plankton and so on up the chain until the toxins became really concentrated in fish and even waterfowl that bald eagles consumed—thus even more concentrated in bald eagle’s body. It leads to interference with calcium deposition during egg-laying. Goldens, on the other hand, sit atop of a terrestrial food chain without significant concentrations of those toxins
Wilkinson: What about differences in distribution?
PRESTON: Bald eagles are limited to North America, while golden eagle ranges widely across the Northern Hemisphere through North America, Eurasia, and even northern Africa. In North America, goldens breed mostly in western states and provinces from Mexico to Alaska, but there is a breeding population in eastern Canada.
Conservationist Kristin Combs discusses the importance of raptors in healthy ecosystems. Combs today is executive director of Jackson Hole-based Wyoming Wildlife Advocates. Photo courtesy Wild Excellence Films.
Wilkinson: How much do goldens migrate?
PRESTON: In winter, goldens in northernmost range migrate mostly south—similar to balds in this respect. Ongoing studies are exploring golden migration in both the Eastern and Western U.S. Though about the same size with same-sized talons, golden eagles generally have more powerful grasp than bald eagles. Estimates are that their strength measures around 500 pounds per square inch of pressure for balds, and more 700psi for goldens.
Wilkinson: Do the species directly compete?
PRESTON: The two species commonly overlap especially in winter, when they both feed on carrion. It’s not uncommon to observe several balds and goldens around large carcass at the same time. Sometimes they tolerate one another, sometimes not. Typically, goldens dominate balds, but much depends on age, gender, size, hunger level, and “personality” of individual birds.
Wilkinson: We at Mountain Journal are nerds and wonks when it comes to understanding how science works. Tell us a bit about the raptor lab at the Draper Museum.
PRESTON: I established our formal raptor research program at the Draper in 2009 to monitor and study reproduction and nesting ecology of golden eagles and other raptors in the Bighorn Basin. 2022 is the 14th year of our program, and we have focused primarily on annual reproduction, diet, and fluctuations in prey abundance and their relationships with one another. We’ve also collaborated with other researchers across the western US to explore lead toxins and disease among nestlings. Additionally, we’ve worked with the Fish and Wildlife Service to tag and track a few nestlings in 2014 with satellite transmitters. Two of these birds were killed by territorial golden eagle areas within the first two years, we lost tracking of another one after four years, and we continued to track the fourth bird.
"The golden eagle is now a species of special conservation need in Wyoming and other Western states. It is unclear how individual factors are interacting to affect their populations overall, both indirectly by reducing prey abundance and availability and directly through interference with nesting and eliminating foraging habitat. In some cases, habitat—mainly grassland and sagebrush-steppe—is undergoing loss/fragmentation/modification and considered a most critical factor." —Dr. Charles Preston
Wilkinson: How many birds have you been tracking?
PRESTON: Altogether, we’ve banded more tthan 90 nestlings and fledglings with USGS and uniquely numbered color bands. We receive information on these birds from various sources when the birds are encountered. We’ve published several papers in peer-reviewed journals and popular magazines, presented more than 50 invited public talks and scientific conferences specifically about our research efforts, reached more than 200,000 members of the general public with other lectures, classes, and field trips.
Wilkinson: Very impressive. The museum itself, I know, is reaching people in region and the large number of tourists who pass through Cody in route to Yellowstone, yes?
PRESTON: In 2011, we established the Draper Museum Raptor Experience, using live, non-releasable raptors to educate the public through in-museum presentations and outreach programs. The Experience has reached an estimated 200,000 to 300,000 people in the past 10 years. In 2018, we installed a permanent exhibition in the Draper—Monarch of the Skies: The Golden Eagle in Greater Yellowstone and the American West. The exhibition uses specimens, artifacts, visitor activated interactives, large-format video presentations, and photographs, to highlight the process and products of our golden eagle research, and similar long-term research programs in Idaho, Yellowstone National Park, Montana, Washington, Utah, and Alaska.
Wilkinson: I know its been an example of public agencies and private entities coming together. And we can never overstate the importance of an enthusiastic staff.
PRESTON: Our research, educational outreach, and exhibition have been funded through more than a dozen agencies and private foundations. Five staff members and more than 60 volunteer citizen scientists and educational volunteers have participated in research and outreach programs and several private landowners have cooperated by granting access and logistic support on their properties. We have been in close contact with golden eagle research teams in Yellowstone National Park (Doug Smith and colleagues) and near Livingston, Montana (Ross Crandall and Craighead Beringia South). We are continuing to analyze data from the last 13 years and exploring the relationship between golden eagle reproductive effort and landscape characteristics and weather, as well as prey abundance.
An eaglet on the nest, surrounded by a banquet of edibles that its parent brought back from successful hunting and scavenging trips. Photo courtesy Wild Excellence Films
Wilkinson: Golden eagle populations in some places are in trouble. What's causing the declines?
PRESTON: Some data indicate relative stability in most of US. range, but the concern is that any stability is fleeting in the face of increased changes. The golden eagle is now a species of special conservation need in Wyoming and other Western states. It is unclear how individual factors are interacting to affect their populations overall, both indirectly by reducing prey abundance and availability and directly through interference with nesting and eliminating foraging habitat. In some cases, habitat—mainly grassland and sagebrush-steppe—is undergoing loss/fragmentation/modification and considered a most critical factor.
Wilkinson: You’ve connected some of this to human pressures that have been growing in Greater Yellowstone.
PRESTON: I view habitat loss, that includes losses to exurban sprawl, increased off-road recreation, energy development, invasive cheatgrass and other species as an existential threat for both reproduction and survival. Additionally, many factors are responsible for mortalities: collisions with vehicles and man-made structures are increasing— especially collisions with the increasing number of wind turbines.
Wind turbines in the "wind belt" of central Montana. Together, Wyoming and Montana possess an abundance of wind resources to power alternative energy but the blades of turbines can be deadly to birds which ride the same wind currents. Photo by Todd Wilkinson
Wilkinson: How is science helping to address some of those threats?
PRESTON: Studies like ours provide information on how managers might mitigate some of these losses in areas without turbines. Lead poisoning is a real problem in some areas, as golden eagles consume carcasses of prairie dogs or other ground squirrels that are killed for sport. They also, of course, feed on big game gut piles laden with lead fragments from lead-based ammunition. Electrocution is still a problem in some areas, though energy companies continue to identify problem sites and retrofit utility poles.
Wilkinson: Another ongoing concern is the use of poison by federal and state predator control specialists targeting coyotes. In addition, how do people out on the rural landscape view goldens?
PRESTON: There is also intentional and unintentional chemical poisoning and we still deal with direct persecution, i.e. shooting. Though there is often little direct evidence of depredation, some livestock growers, especially sheep operations, assert that golden eagles kill many of their stock. Most ranchers work with state and federal agencies to assess and address issues, but there remains an attitude among some folks, especially in the West, that predators should be eliminated when the opportunity arises.
Wilkinson: What about shifting precipitation and rising temperatures?
PRESTON: Climate change, of course, is another existential threat in both the short and long term. Projections indicate that warmer, drier climate in current grasslands, shrub-steppe, and other similar habitats, will not be able to support current numbers of golden eagles and their prey.
Goldens grow up fast. They have no. These young eagles, that inhabit the Bighorn Basin, are part of Preston's research into how habitat change and environmental factors are shaping the specie's prospects for survival. Photo courtesy Wild Execellence Films
Wilkinson: Earlier, you mentioned cheatgrass. How does the proliferation of this non-native plant affect golden eagles and is there a climate connection?
PRESTON: The proliferation of cheatgrass continues to negatively impact habitat for eagles and other species. Cheatgrass cures early in the summer and becomes excellent fuel for wildfires. When these wildfires remove native shrubs and grasses, cheatgrass expands. Cheatgrass is the perfect pioneering species, and it was first introduced to North America from Eurasia around the turn of the 20th century or before to provide early season forage for livestock. But it’s a problem for native plants and animals.
Wilkinson: The last question goes to your filmmaker collaborator David Rohm. What do wish your documentary will accomplish?
ROHM: We sincerely hope our film can certainly change some things. The West is in serious trouble, and golden eagles not that far behind. We really feel for the locals, we want them to know we did this film for them as well as eagles, their way of life is changing, rapidly, affecting livelihoods and most wildlife. Maybe if people can see that eagles can think, understand, feel and display emotion, they have their own lives and problems and challenges, just like us.
About Todd Wilkinson
Todd Wilkinson, founder of Mountain Journal, is author of the book Ripple Effects: How to Save Yellowstone and American's Most Iconic Wildlife Ecosystem. Wilkinson has been writing about Greater Yellowstone for 35 years and is a correspondent to publications ranging from National Geographic to The Guardian. He is author of several books on topics as diverse as scientific whistleblowers and Ted Turner, and a book about the harrowing story of Jackson Hole grizzly mother 399, the most famous bear in the world which features photographs by Thomas Mangelsen. For more information on Wilkinson, click here. (Photo by David J Swift).
