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Researchers Continue Long-Term Study Of Wyoming’s Golden Eagles in Big Horn Basin

in News/wildlife
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By Wendy Corr, Cowboy State Daily

Researchers in Park County are keeping an eye on golden eagles in the Big Horn Basin as an indicator of the health of the area’s ecosystem.

According to biologists, the golden eagle is a species of greatest conservation need because of the rapidly changing conditions of its primary habitat. 

Dr. Charles Preston is the curator emeritus for the Draper Museum of Natural History at the Buffalo Bill Center of the West in Cody. For the last 12 years, his staff and a group of volunteers have been keeping a close eye on the golden eagle population in the Big Horn Basin.

“Because raptors are the top of the food chain – and, so they give us an idea of what’s going on with the ecosystem,” Preston said. “And I’m really interested in ecosystem dynamics, how ecosystems change through time. Raptors give me a good window into that.”

Each year, select birds are banded, measured, weighed and their general condition is determined. This year, feathers were collected from the golden eagles as well.

The team also collects the remains of prey found in the eagles’ nests to study how what they eat affects their reproductive cycles. 

Data from the study will be stored in the McCracken Research Library at the Buffalo Bill Center of the West in Cody for the public to access. 

But it’s not just the predator-prey relationship that the study has focused on, according to Preston. People are also a large part of the equation.

“It’s important to understand how our activities affect, both positively and negatively, the wildlife,” he said. “Because almost everybody wants to maintain a healthy wildlife population and community.”

Preston noted that continuous, long-term research is the key to this study – especially for a species like the eagle.

“Because things change from year to year, whether it’s weather, or prey abundance, or landscape, those changes are important,” Preston said. “So just a couple of years, a snapshot in time might be valuable for one thing, but it doesn’t give you a big picture.”

With the advancements of wind farms and other energy development, an increase in outdoor recreation, and residential construction encroaching on the birds’ habitat, Preston said studies like this one will continue to provide valuable information.

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The Bloody Sire Inhabits the Sagebrush Sea

in Cat Urbigkit/Column/Range Writing/wildlife
Pronghorn nursery
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By Cat Urbigkit, Range Writing columnist for Cowboy State Daily

What but the wolf’s tooth whittled so fine

The fleet limbs of the antelope?

What but fear winged the birds, and hunger

Jewelled with such eyes the great goshawk’s head?

Violence has been the sire of all the world’s values.

From: The Bloody Sire by Robinson Jeffers (1940s)

It’s been an interesting week on the ranch, which is located amid the sagebrush sea of western Wyoming. We had our first confirmed depredation of a 20-pound lamb by a pair of adult bald eagles. This was somewhat of a surprise since our livestock guardian dogs tend to harass big birds that come near the flock, and because most confirmed eagle depredations on livestock are inflicted by golden eagles – not bald eagles. I had watched a pair of golden eagles hunting over the sheep flock the week prior and was relieved when a spring snow squall pushed the eagles away from the flock.

While we were on watch to keep eagles away from the lambing flock, our game cameras revealed the presence of a radio-collared wolf making numerous forays onto the ranch, even coming within a short distance from the house. The cameras revealed our livestock guardian dogs tracking the wolf but returning to their sheep a few hours later. This male wolf was new to the neighborhood but is in addition to an adult female wolf we helped collar last December after numerous livestock depredations and removal of several members of her pack. That at least two collared wolves were roaming our lambing grounds along the Wind River Front is a concern akin to a ticking time bomb. There will be violence – the only uncertainty is when.

With everyone on high alert in trying to avert an animal catastrophe, the sheep are bedded on high ground each night about a half-mile from the house. I’m out as the sun starts rising to feed the guardian dogs and see the sheep off to their day’s grazing. We can generally tell by the behavior of the livestock guardian dogs whether there are wolves in the area. When the wolves are making their forays onto the ranch, the dogs are hyped up, driven by adrenaline, and looking for a fight. When the wolves aren’t around, the dogs are much more relaxed.

Pronghorn triplets
A pronghorn antelope doe with her triplet fawns.

Spring seems to have come late to western Wyoming this year, but by the second week of June the pronghorn antelope that shares our range were dropping their fawns in all directions. It seemed nearly every predator we saw in the last few days had a fawn carcass in the grip of its jaws. Worried about the survival rate of these fawns, an event I witnessed gave me hope and reminded me of the Robinson Jeffers poem quoted above.

As I drove down the county road which splits our pastures, I watched a coyote cross from one pasture to another. A mixed group of pronghorn antelope does and bucks were in that pasture, and a doe immediately took to chasing the coyote. It wasn’t enough to chase it out of her immediate vicinity – the doe performed like a good cow horse, meeting every dodge and turn of the coyote with her own maneuvers, and coming so close to stomping the coyote into the dirt.

The doe chased the coyote over half a mile before it fled under the far boundary fence to safety. According to scientific literature, the doe’s anti-predatory defense isn’t unusual, and this aggression exhibited by a prey species toward a predator is nearly always undertaken by adult females. (I also found a great account of a pronghorn doe teaming up with a short-eared owl to harass a coyote away from an active owl nest.)

Pronghorn chases coyote
A pronghorn doe aggressively pursues a coyote.

Generally as wolf densities increase, coyote densities decrease, but we have both species on the ranch, and know that both species prey on pronghorn antelope here. But many predators – from coyotes and wolves to eagles and bears – are successful at searching out newborn prey species that hide.

A study of grizzly bear depredation on elk calves in Yellowstone National Park found the most common hunting technique used by grizzlies was searching for bedded calves, with one bear catching five calves in 15 minutes. Like our pronghorn doe, cow elk will attack predacious bears, as do cow bison.

Research on white-tailed deer fawns in Minnesota found that all radio-tagged fawns in the study were killed by predators, with a near-even split between wolves and black bears.

The first two weeks of life are the most dangerous for newborn fawns and calves, but as each day passes, they grow and gain strength. By the time pronghorn fawns are two months old, they are outrunning predators nearly as ably as their protective mothers.

Cat Urbigkit is an author and rancher who lives on the range in Sublette County, Wyoming. Her column, Range Writing, appears weekly in Cowboy State Daily.

Golden Problems, Working Solutions

in Uncategorized
Golden eagle talons.
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By Cat Urbigkit, Range Writing columnist for Cowboy State Daily

Imagine being a commercial sheep producer in Wyoming and losing 15 percent of your annual lamb crop to a federally protected predator. Then as each year passes, your livestock losses increase as more of those federally protected predators concentrate depredations on your flocks. The losses climb so that fully half of your lamb crop is lost to these predators. 

That’s the reality for Johnson County’s Tommy Moore of Moore Ranch Livestock, which lost half of its lambs to golden eagles last year. The Moore outfit had about 200 lambs born earlier this year, but 27 lambs are left alive at this point, with 80 percent of that death loss due to golden eagles.

It’s not a sustainable situation and everyone knowledgeable about this case understands that.

That’s why Moore has teamed up with the Wyoming Wool Growers Association, and Mike Barker of the International Eagle Austringers Association (a group of eagle falconers) to organize a coordinated effort to get some of the depredating golden eagles off his ranch. That work has drawn in several federal agencies, the Wyoming Game & Fish Department, the North American Falconers Association, numerous volunteer falconers and scientists from across the country, and U.S. Senator John Barrasso. 

Barrasso – quietly and successfully – amended the federal eagle protection act last fall to require the director of the U.S. Fish & Wildlife Service (FWS) to “use the most expeditious procedure practicable to process and administer permits” for the take of depredating eagles.[

“That really helped to push this through,” Barker said. 

A golden eagle in flight in western Wyoming.
A golden eagle feeds on a dead pronghorn antelope in Wyoming. (Photo: Cat Urbigkit)

Prior to a mid-1970s study documenting severe eagle depredation on Montana lambing grounds, the public (and some wildlife agencies) were skeptical at rancher claims of eagle depredations.

Bart O’Gara of the Montana Cooperative Wildlife Research Unit documented a similar kill scenario to the Moore’s Johnson County ranch on two Dillon, Montana-area ranches in the 1970s. In one six-hour period, O’Gara found 15 fresh eagle kills on one ranch, and that year, federal officials removed 145 golden eagles from the two ranches, which suffered losses totaling 76% of their lamb crop. Over a period covering three springs, nearly 250 golden eagles were removed from the ranches and depredations began to decline.[

With USDA Wildlife Services confirming the eagle depredations on his Wyoming ranch, the U.S. Fish & Wildlife Service issued Moore a depredation permit allowing the removal of two eagles. Moore agreed to work with the International Eagle Austringers Association so that the two eagles removed pursuant to his permit would be used for falconry, while other eagles that are captured are to be relocated away from the area.

A total of 27 eagle falconers applied to trap a golden eagle, and two names were drawn, including lucky man Barker and another falconer from New Mexico. Within six days, the trapping team captured a male eagle for the New Mexico falconer, and three days later, caught a female eagle for Barker. Both are immature golden eagles, so they were not part of the breeding population.

Now that two eagles have been removed from the population under the depredation permit, all other eagles captured on the ranch during the 90-day term of the permit will be relocated away from the ranch. Two other eagles have already been relocated, and live trapping efforts continue.

A golden eagle feeds on a dead pronghorn antelope in Wyoming.
A golden eagle in flight in western Wyoming. (Photo: Cat Urbigkit)

Similar efforts to stop eagle depredations on sheep have been successful in South Dakota. Other tactics, such as using scare devices, are generally viewed as ineffective at deterring eagle depredation on range sheep operations.

Eagle depredation on domestic sheep isn’t limited to newborn lambs, as Moore points out. They also attack and kill adult sheep and antelope. Golden eagles also killed a number of Moore’s replacement ewe lambs (weighing about 100 pounds) last fall. For the benefit of those not involved in the domestic sheep business, I’ll add that in my view, replacement ewe lambs are the future of any family sheep outfit.

While the eagle problem on the Moore ranch varies with the weather and with the season, the ranch experienced heavy damage in February (before his depredation permit was issued), and Moore expects problems to increase again this fall, if last year’s pattern is any indication.

The FWS has been hesitant to allow the removal of golden eagles, only allowing up to six goldens to be taken for falconry nationwide, so nearly all the golden eagles used for falconry in the United States were captured in the wilds of Wyoming. But FWS has not allowed any eagles to be taken from the wild since 2011 – until Barrasso pushed through the amendment to the eagle act last fall, and wool growers teamed up with falconers to push for action in Johnson County.

The wool growers/falconry partnership will continue, with numerous volunteer citizen scientists and falconers arriving on lambing grounds in other regions of the state in the coming days to monitor eagle depredations on lambs through the month of June. They will assist USDA Wildlife Services in confirming eagle depredations where problems are reported, which will set the stage for more ranchers to follow Moore’s lead in applying for depredation permits and requesting that falconers be allowed to trap and remove eagles from depredation areas.

The end result is that rather than pushing another domestic sheep producer out of business, the Moore family can continue their ranching heritage, and problem eagles will be removed from the wild, to hunt with their falconry advocates for decades to come.

Cat Urbigkit is an author and rancher who lives on the range in Sublette County, Wyoming. Her column, Range Writing, appears weekly in Cowboy State Daily.[

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