On small ranch parcels and near wooded nooks, hidden cameras triggered by anything that moves are capturing images of the North's mightiest winged predators this winter in the Bitterroot.
No one knows for certain what researchers will learn from the thousands of images of eagles swooping down to feed on carcasses strategically placed around the valley.
But through the magic of the internet, people from both near and far will have a chance to take part in helping identify the golden and bald eagles that have stopped in for a bite on private lands scattered about the valley floor.
This winter’s camera trapping operation in the Bitterroot Valley is being led by Rob Domenech, executive director of Missoula-based Raptor View Research Institute, and MPG Ranch ecologist Kate Stone.
As of last week, the project had 12 cameras recording everything that has fed on deer carcasses from Lolo to Sula since December.
The photographs they’ve captured so far have been remarkable.
In one, a bald eagle with its wings spread wide stares down a magpie resting on a rib cage bleached white against the snow. A second photo shows a group of crows watching intently as a bald eagle swoops down on a golden eagle standing atop a carcass.
The photographs captured between December and March may add a puzzle piece or two to the understanding of how eagles make use of the winter habitat offered in the Bitterroot.
“We already know that eagles have an incredible fidelity to the Bitterroot Valley,” Stone said. “Golden eagles return here year after year to winter after breeding in the far northern reaches of Canada and the wilderness of Alaska.”
Since 2011, the two research organizations have been working together to capture and either band younger birds or place tiny GPS transmitters on older eagles that provide exact locations of the birds up to 12 times a day.
“Some of the birds that we’ve fitted with transmitters here in the Bitterroot have summered in the Brooks Range in Alaska,” Domenech said. “And then they come back down here to winter. The transmitters have been a great way to learn about how eagles use the mixed habitat here in the Bitterroot and to find important migration corridors.”
The solar-powered transmitters weigh between 45 and 90 grams and are about half the size of a pack of playing cards. They are designed so the eagles can pull them off whenever they choose.
One eagle that researchers have nicknamed “Wanderer” for its frequent forays from the Bitterroot to Glacier and the Rocky Mountain Front has been packing a transmitter since 2013.
“That transmitter is still going strong,” Domenech said.
Since the transmitters are expensive, they are reserved for adult birds.
“The reason we target adults is because they are the tried and true survivors,” he said. “We know that they can make these long migrations because they have done it before. We know from band returns that eagles can live up into their mid-30s. I think they can live longer than that. I believe there are bald and golden eagles that are 40 years plus.”
While the conservation success story of bald eagles is well known, Domenech said there is a lot of evidence that golden eagles are in decline.
No one is certain why that’s occurring.
Many are lost to vehicle collisions that happen when an eagle feeds on carrion too near a road. Some die from electrocution from power lines or from being shot. Changes in habitat can be a problem, too.
In the Bitterroot, the presence of lead in blood samples taken from captured eagles has been a troubling trend.
Of the 70 eagles that researchers have captured in the valley, 89 percent have had elevated levels of lead in their blood.
“The wintering birds here show really high levels of lead,” Domenech said. “We have to assume that they are getting that here in the valley.”
And eagles aren’t the only creatures being impacted.
Both Stone and Domenech believe that eagles pick up most of the lead while feeding on gut piles left behind by hunters.
Stone said a lead bullet can lose up to 20 percent of its mass after striking an animal. X-ray scans show elk and deer killed by a lead bullet are full of lead fragments.
“That means the hunter is consuming the lead and anyone in their family who eats the meat is consuming it, too,” she said.
“That’s a conservation message that we’re trying to spread. There are private landowners and block area managers who don’t want lead used on their property anymore.
“We have long accepted lead as poisonous in so many other uses,” she said. “It’s a conservation message that people can actually do something about. Finding a way to impact global climate change might seem daunting, but everyone who hunts can do something about lead.”
By tracking the movement of eagles in the Bitterroot, Stone said the researchers have also learned just how important private lands in the valley are to the raptors. Many of the camera sites have been set up on land protected by conservation easements.
“This research really provides some solid data on how important those working lands are to wildlife,” she said. “It’s been a way to open up dialogue with the ranching and farming community that is really valuable.”
The hope is that others interested in citizen science will find time to log on to zooniverse.org to help the two researchers sift through the thousands of photos captured this winter.
“The website allows anyone in the world to help tag animals in images,” Stone said. “Anyone can participate. They can look at our images and help us identify the birds that show up. If they see an eagle with a tag, they can let us know about that, too.”
“So instead of me going through 5 million images — which wouldn’t be possible — we can get some help from others,” she said. “Last night, I was tagging penguins.”
Anyone interested in learning more about the ongoing project can attend a talk and fundraiser from 5:30-8 p.m. Jan. 26 at the Stevensville Café.
“People can learn how they can participate and see how to process images there,” she said.
The researchers will also be set up at the MPG Lab on Missoula’s First Friday in February. The lab is located in the Lambros Center at 1001 S. Higgins.
Stone has also started a crowd sourced fundraising effort for the project: crowdrise.com/bitterroot-valley-winter-eagle-project/fundraiser/katestone3.