MISSOULA — Three golden eagles caught in separate snare traps over the past few days have raised concerns among biologists who are racing to understand what’s causing the raptor’s migratory population to dwindle across the region.
The Montana Raptor Conservation Center in Bozeman posted an image of one injured eagle on its Facebook page. The bird arrived at the center tangled in what remained of a wire snare.
Of the three trapped eagles, it was the only one to survive. Whoever found the raptor cut the snare, but left the bird to wander with the cable embedded in its wing and shoulder.
“It started pretty much last Thursday when we received the first eagle dead on arrival,” said Becky Kean of the Bozeman center. “We got the second one in Friday and it’s still with us. The third one had to be euthanized at the trap.”
Kean said one of the birds was caught in a snare trap near Ringling. The other two traps were set near Big Timber. The surviving eagle is scheduled for surgery Tuesday to mend wounds left by the snare.
“That cable dug in pretty deep,” Kean said. “We usually see four trapped eagles a year, but they’re usually leg-hold traps. This is the first we’ve seen of snares, and there have been three of them now.”
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Biologist Rob Domenech, founder and president of the Raptor View Research Center in Missoula, said it wasn’t the first time golden eagles have been caught in traps.
Yet losing three birds to snare traps in such short order has raised concerns among biologists, who are working across the region to understand why migratory golden eagles are declining in number.
“One of the trapped birds was a bird we put a satellite transmitter on in October 2010 at Nora Ridge off Flesher Pass,” Domenech said. “We were tracking her, and it was the third year of us following her.”
By tracking the bird, Domenech and his team learned that the eagle summered in the Brooks Range of Alaska before heading south for Montana each winter.
It traveled to the Paradise Valley and the Gardiner area, and was fond of the Bridger and Big Belt mountains. Losing the bird to a snare was a setback for the study, both scientifically and emotionally.
“We’ve become attached to these birds on some level, and this one had given us a ton of information in terms of migration routes and the size of wintering grounds,” said Domenech. “Now she’s given us information on a cause of mortality. It’s not a happy ending, but it is data for our research.”
Tom Barnes, president of the Montana Trappers Association, declined to comment Monday on the separate incidents until he learned how the eagles were snared and where the traps were placed.
Barnes did say that Montana has rules in place to minimize the accidental trapping of non-target animals. The rules cover where snare traps are placed and how much bait can be used.
“There are restrictions on how they (traps) can be set for exposed bait,” Barnes said. “I have no idea how these (traps) were set. Without finding out what happened, I don’t feel comfortable commenting on it.”
Biologists have been working to understand more about golden eagles and what’s killing them. When transmitters stop working, Domenech said, scientists typically find the birds dead.
He said the causes nearly always stem from human factors, including electrocution, poisoning, car collisions and accidental trapping.
“In all the years we’ve been doing this, I don’t recall any time where we’ve had three incidences with eagles in snares in as many days,” he said. “That throws up a red flag that there’s something else going on out there.”
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Golden eagles may be facing a new threat in the West, where energy development is advancing at a rapid pace. While the birds have adapted to coexist in a human-dominated environment, there are limits to their ability to change.
Steve Hoffman, executive director of the Montana Audubon Society in Helena, started the Bridger Raptor Migration Project in 1991 with a focus on golden eagles. The group’s 21 years of data has shown a marked decline in the population.
“We’ve seen a 40 to 50 percent decline since 1999,” said Hoffman. “That’s across all the life stages of the eagle. It’s a great concern for all of us.”
Like others in the field, Hoffman attributes the decline to a number of factors. Among them, he’s focused on the loss of quality habitat and the abundance of prey – primarily the availability of jackrabbits on the sagebrush steppes of Montana and Wyoming.
“That’s where we’re seeing a huge expansion of energy development,” Hoffman said. “Golden eagles are one of the most adaptable, widespread raptors on the North American continent. The environment has to change very rapidly for them to have problems.”
To ramp up their study of golden eagles and understand their declining numbers, biologists have issued a call for information – a challenge to the scientific community to study the birds and do it fast.
Domenech and his team are now tagging more golden eagles in a cooperative study taking place on a Bitterroot Valley ranch. Many of the birds that migrate south for winter won’t make it home, and biologists want to know what’s killing them during their southern forays.
“The transmitters are part of greater mortality study,” Domenech said. “We’re trying to get as much information on golden eagles and causes of mortality. It’ll give us a better idea of what’s taking these birds out.