Researchers study golden eagles in Oregon

In Wallowa County, the Oregon Department of Fish and Wildlife has led collaborative research on golden eagles. The pilot project aims to study the survival, movement and reproductive success of the birds. ODFW worked with the U.S. Fish and Wildlife Service and the Nature Conservancy to capture data.

The golden eagle uses a variety of habitats and seeks rocky cliffs or large trees. It can dive at a speed of 120 miles per hour and preys on animals including squirrels and foxes. Humans are largely responsible for their decline. The birds collide with wind turbines, face habitat loss and are killed illegally.

Holly Tuers Lance is the acting district wildlife biologist for the ODFW field office based in Enterprise. She joins us with more about the raptors and the work being done locally.

Note: The following transcript was transcribed digitally and validated for accuracy, readability and formatting by an OPB volunteer.

Dave Miller: From the Gert Boyle Studio at OPB, this is Think Out Loud. I’m Dave Miller. We turn now to a new collaborative research effort to better understand golden eagles in Eastern Oregon. The Oregon Department of Fish and Wildlife is partnering with the U.S. Fish and Wildlife Service and the Nature Conservancy to learn more about the survival, movement and reproductive success of these massive raptors.

Holly Tuers Lance is the acting district wildlife biologist for the ODFW Field Office based in Enterprise, and she joins us now. It’s great to have you on Think Out Loud.

Holly Tuers Lance: Yeah, thanks for having me.

Miller: I mentioned that these are massive raptors. Can you give us a sense just for their size?

Tuers Lance: Yeah, so they are large birds of prey. Typically of any bird of prey, females are larger than males, so female golden eagles can weigh anywhere from 8 to 14 pounds with a wingspan of 6 to 7 feet. They’re very large birds.

Miller: Where can they be found?

Tuers Lance: Pretty much anywhere in any of the counties east of the Cascade Range. They occupy most habitat types found east of Cascades.

Miller:  I mean, is it fair to say that they’re pretty adaptable birds?

Tuers Lance: They are. Yeah, that’s a fair assessment.

Miller: What do they eat?

Tuers Lance: They’re a bird of prey, so that means they hunt small to medium-sized animals, but they will also scavenge on carrion that they find.

Miller: How are they doing population-wise nationwide?

Tuers Lance: There is some concern. There are declining population trends nationwide and at a state level, so we’re interested in seeing if those trends hold true in our localized area.

Miller: Do you have a sense for what the reasons are for their population declines?

Tuers Lance: Not particularly. There’s a lot of different factors that can influence populations of different species. For golden eagles, there’s a couple different things that could be influencing their populations. Disturbances in areas where they nest or forage can cause reproductive failure, which can lead to population decline. Additionally, a high rate of mortality in your adult birds from things like vehicle strikes, strikes with turbines, electrocution, poaching is pretty high and exposure to toxins on the landscape. There’s a lot of things that can kill these birds. So those are all different causes of mortality that could lead to a declining population.

Miller: What are their numbers like in Oregon?

Tuers Lance: That’s a great question. I don’t have a good answer for you. We’re interested in a smaller scale than just the statewide number and we’re just looking at survival. So we’re interested in seeing how these birds are doing in our specific area, not across the state.

Miller: So what’s the big idea behind this pilot program that you’re doing with the U.S. Fish and Wildlife in the northeast corner of the state?

Tuers Lance: As you mentioned, it’s a collaborative study looking at gaining a better understanding of golden eagle movements and localized population trends. We have two specific objectives. We want to assess golden eagle movement ecology and habitat use in Northeast Oregon. And then we want to look at occupancy and reproductive success in their nesting. So for objective one, we are trying to capture and radio tag golden eagles in Northeast Oregon, and that gives us GPS locations of where these birds are going or traveling across the landscape. Also, with that unit on these birds, we’re able to find them if they were to die and we can get co-specific mortality from conducting the necropsy investigations on those birds. Then surveying nest sites, we can go to historically known nest sites and look for occupancy, and then over time we can see if they were reproductively successful from chick to fledging.

Miller: The press release for this pilot study said that very few people in the U.S. have the certification and experience necessary to handle eagles, but that one of them is a U.S. Fish and Wildlife biologist who works in Oregon named Matt Stuber. What has he been doing for this study?

Tuers Lance: Matt’s been great. We needed somebody who had the certifications, qualifications and skills necessary to catch birds for our first objective to put radio trackers on them. Matt, as a partner with this project, came out to Wallowa County this winter for our pilot study. And in six capture days, he helped us catch five birds [and] we were able to put GPS backpacks on four of them. So Matt was essential in getting that part of the project going.

Miller: So right now, there are five eagles with little backpacks on them, flying around or roosting in various places in Wallowa County?

Tuers Lance: Yeah, there’s four eagles with GPS backpacks on them, yep.

Miller: Were you there on hand when he was capturing some of them and putting these backpacks on?

Tuers Lance: Yeah, I was there for one of the capture events. It’s quite the process. You have to go out before sunrise and sneak into a ground blind in the dark, so the birds don’t know you’re there. You have your traps set up with bait, and when the birds come in, you just kind of wait until that happens. Then you catch one with this net that’s set up on the ground. You get them out of the net. Then Matt puts the GPS backpack unit on him and lets them go.

Miller: And I imagine these are light enough that the birds don’t mind too much that they’re now wearing backpacks.

Tuers Lance: That’s correct. They’re not very big. They sit on their back, between their shoulders and between their wings. And they don’t impact their ability to fly, hunt or any of their normal behaviors at all. The unit’s very, very light and it’s a solar powered unit, which also increases the fact that it’s lighter because it doesn’t have a battery in it. And those units will be on those birds for the lifespan of those birds and they’ll be sending us continuous points as those birds sit in the sun. The GPS unit will send us points of where it’s located.

Miller: What kind of data have you already been getting?

Tuers Lance: We have units on two adults and two sub-adults. For one of the adults, she appears to be nesting and we’ve verified that she’s on a nest with eggs from ground surveys that we’ve done. Some of our sub-adult data is really interesting. We had one bird that kind of left the county for a while, went to Idaho, went down to Baker County, came back. As a sub-adult, it’s still looking for its territory. It’s not breeding yet, so it’s just kind of flying around a larger area, which is super interesting to watch.

Miller: That reminds me a little bit of talk about wolves. Folks may remember OR-7 years ago who just went all over the place, ended up, I think, in California. But is this sort of regular golden eagle behavior, that when they are, as you say, sub-adults, it’s up to them sometimes to go off and find their own place to live?

Tuers Lance: Yep, so birds of prey are territorial. They hold a specific area that’s their territory. So these sub-adults who aren’t quite ready yet to breed are just flying around and seeing what territories are unoccupied, what areas that they could establish and set up shop when they are ready to breed. We also got lucky in the fact that none of the birds that we happened to tag this year were non-residents. There is a population of non-resident birds that migrate south from Alaska to Oregon to spend the winter, to overwinter here, and then they’ll go back to Alaska in the spring and breed up in Alaska. So we got lucky that we didn’t happen to catch any of those birds.

Miller: Why is it important to partner with these other organizations: U.S. Forest Service and Nature Conservancy?

Tuers Lance: In any projects that we do, it’s a lot of work and a lot of time and commitment. And having these partnerships and collaborations helps spread the workload out. The Forest Service is already doing quite a few nest surveys on their property. We partnered with the Nature Conservancy in order to use some of their land for capture locations. They happened to have done some recent surveys that had known eagle territories within those areas and we wanted to target those for some of our winter captures. So when we partnered with them, not only was it helpful to us to be able to meet the objectives of our project, but it was helpful to them because now they have some eagles that have been marked on their property. They can see what habitat they’re using and then they can adjust their management style for that species.

Miller: You are at a state agency, Oregon Department of Fish and Wildlife, but has this partnership been at all affected yet, or so far, by budget and staff reductions at the federal level?

Tuers Lance: Not directly. The federal agencies that we have partnered with have lost staff, and that’s unfortunate. It does lead to less productivity. We’re doing everything we can to try to help assist them with their workload because we’re all in this together. So it is an impact that has been felt by all of us.

Miller: I have called this a pilot project. What is next for this?

Tuers Lance: Right now, we’re in the middle of our nest surveys. We’re doing them in all four counties in Northeastern Oregon, and that’ll continue through midsummer. And we put in a grant request for some money to hopefully continue tagging birds the next couple winters and we’re just waiting to hear back if we’ve secured some money for that.

Miller: Holly Tuers Lance, thanks very much.

Tuers Lance: Yeah, thank you.

Miller: Holly Tuers Lance is the acting district wildlife biologist for the Oregon Department of Fish and Wildlife’s office based in Enterprise in Wallowa County.

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