The study to keep the northern spotted owl from extinction has been going on since 1985, and a primary cause of the birds continued decrease in numbers is the barred owl – an invasive species from the eastern United States that has outcompeted the spotted owl for food and habitat. To address this competition head on, Dr. David Wiens of the United States Geological Survey’s Corvallis office has recently completed a 17-year study.
We sat down with Wiens to talk about the different ideas considered, and what seems to be the most effective and ethical of them all – shooting the invaders.
TCA: Hi, I’m Sally Lehman, and I’m with The Advocate.
If you’ve lived in Oregon, you’ve heard of the fight to keep the northern spotted owl from going extinct. Today, we’re speaking to Dr. David Wiens of the United States Geological Survey’s Forest and Rangeland Ecosystem Science Center, who has been part of a 17 year study of one of the issues working against the spotted Owls – another owl species known as the barred owl. Thank you for being here today, Dr. Wiens.
Wiens: Thank you for having me today.
TCA: Your education took you through Arizona, Colorado, and Oregon. Are you originally from the western United States?
Wiens: Yes. In fact, I actually was born in Corvallis. Oregon, lived here until I was about eight years old, and then moved around various places in the western U.S. through Arizona, New Mexico, Colorado.
TCA: So glad to have you back.
Wiens: Oh, thank you. It’s wonderful to be back.
TCA: You began your career studying the Northern Goshawk, which are not currently protected. What did your research into these birds find?
Wiens: We were studying Northern Goshawks in Arizona, near the Grand Canyon, in this area where the species was thought to be facing similar issues as the northern spotted owls – declining populations from timber harvesting and logging were the main concerns. I worked with the Forest Service and we did a large scale study. It was showing that the population is in pretty good shape in that particular area, actually, despite the forest management. And actually some of those recommendations, the forest recommendations for Northern Goshawks that had been implemented in that region, were actually benefiting. Northern Goshawks are an amazing species – another forest dependent raptor species, much like spotted owls and barred owls.
TCA: Your doctoral dissertation concerned the northern spotted owl and the barred owl issue. What were your findings at that time?
Wiens: Yes, we did a large study just here in the Coast Range, west of Corvallis, looking at how spotted owls and barred owls were interacting. More specifically, we were looking at how the two species were sharing space and food, their prey resources, and also just looking at their numbers – differences in their numbers.
At this point, barred owls were a new species in the West Coast forests – they’re an invasive species. They were to be starting to impact northern spotted owls pretty heavily. And from the original work that I did with Oregon State, that we completed back in 2009, we found not only that barred owls were then outnumbering spotted owls by about three to one, but they were basically out competing spotted owls for critical resources such as nesting habitat and the older forest types, [and for] prey resources in particular.
So with that research we were able to determine pretty definitively that barred owls were a problem for spotted owls as they invaded the northern spotted owls range.
TCA: Do we know why the barred owls began to expand westward in the early 20th century?
Wiens: There are a couple hypotheses.
Barred owls are a native species to the eastern portion of North America. We know that they began expanding their range right around the turn of the century, about 120 to 130 years ago now. And at that time, their range expansion very much coincided with European settlement across the Great Plains. And that was one of the main questions: how did barred owls, a forest dependent species, make it across the Great Plains region – this largely treeless region? And some of that coincided with some changes that were taking place during that period with European settlement.
The other hypothesis that has been put forward is [that] there were some natural changes in the climate around that time, particularly in the northern regions of the boreal forests of Canada. Which is another route that barred owls took to get to the western portion of the United States. And so the thinking there is that the climate had changed enough to allow barred owls to persist in areas where they otherwise wouldn’t have been able to around that time.
We looked at that evidence and it pretty heavily points towards a human-caused range expansion that coincided with European settlement. But personally, I think there’s a whole combination of both of those things happening at that time, and there are also some changes in the climate happening that could have allowed barred owls to be places that you wouldn’t find them otherwise.
TCA: Can you outline the basics of the Northwest Forest Plan for me?
Wiens: Just very generally, the Northwest Forest Plan was implemented shortly after the spotted owl was listed as a threatened species and subspecies in 1990. The Northwest Forest Plan was implemented in 1993, and it is an ecosystem-based management strategy that is mandated by several federal agencies, including the Forest Service and Bureau of Land Management. But it’s an ecosystem-based approach that spans the entire range of the northern spotted owl, and its goals are to provide conservation for biodiversity in addition to forest products. So its goals are twofold – to continue to provide forest products to the community while also conserving biodiversity.
TCA: And has the Northwest Forest Plan helped to maintain the spotted owl population?
Wiens: I think so. Without the Northwest Forest Plan being implemented on the federal lands within the northern spotted Owls range, I think things would be in a much worse shape than they are now for spotted owls. In fact, prior to the major fires that we’ve seen in the past couple of years, we’re actually seeing increases in northern spotted owl habitat in areas managed by the Northwest Forest Plan. So it was taking things in the right direction for spotted owls and other old forest dependent species. Of course, several of the large forest fires that we had in the last couple of years have put another dent in that.
TCA: Recently, it was reported that other birds, I believe it was condors, had decided to nest at the top of a burnt out stump, and they had to be carefully moved. Is it possible that the spotted owls can adopt and adapt in that way?
Wiens: Oh, I think very much so. You know, historically, spotted owls evolved in fire prone forests in the Pacific Northwest, so they’re highly adaptive to fire and the impacts that it has on forests.
What we’re seeing more recently, however, is this move of the fire regime to outside of what we saw historically – much larger, more severe fires, and spotted owls can still use those burnt landscapes. But when you get those very large and severe fires, those impacts become more severe on spotted owls.
TCA: In your recent study you found that lethal removal of the barred owl benefitted the spotted owl. How are the barred owls lethally removed?
Wiens: It’s a process that took several years to develop, very carefully, because we wanted it to be a process that’s as ethical to the birds as possible. It was determined before I even started the work as the lead scientists on the project that the most ethical approach to removing barred owls from spotted owl habitats and spotted owl territories was lethal removal using shotguns – 12 gauge shotguns. That process does involve using taped calls or recorded calls to lure in the birds as they go in to chase off what they believe are territorial intruders into their territories.
Some of the alternatives to doing that lethal removal were to do relocations and captures of barred owls. But that becomes very, very costly and complicated. Where are you going to take the barred owls? Where are you going to put them? You can’t hold them indefinitely. And it was determined that, you know, actually doing the lethal removal was probably the most ethical thing to do, the least of the evils that we were dealing with.
TCA: Another issue working against the survival of the spotted owl is the reduction of old growth forest in a state that’s heavily reliant on the timber industry. That must be quite a fight for you and your colleagues.
Wiens: Oh, I wouldn’t say it’s so much a fight. In fact, we coordinated very closely with several large timber companies on our large scale study and barred owl removal experiment. And coordinate very closely with them on the long term monitoring programs for northern spotted owls as well. On federal landscapes, I think, there’s a different management tactic than what’s happening on private timberlands in Oregon.
In a sense, there’s been a type of balance achieved in some of these areas managed by the Northwest Forest Plan.
TCA: On a regular year, one without outrageous wildfires, approximately how much of the spotted owl habitat do you lose on average?
Wiens: Oh, I don’t think I have a good answer for that. And like I said earlier, prior to the large fires, we’re actually seeing gradual increases in the amount of available spotted owl habitat on federal lands. If you look at available spotted owl habitat on private lands, that’s probably a different story. But on federal lands, we were actually measuring increases in the amount available of spotted owl habitat.
TCA: Has climate change affected spotted owl habitat?
Wiens: Yes, undoubtedly it has, I think.
You know, the thing that’s interesting …, when we talk about a spotted owl habitat, we’re really talking about the tall, older trees that Oregon is so well known for. And something that’s interesting about those tall old stands of trees is that they actually serve as a buffer against climate change, we’re finding.
Some studies are finding that those areas are actually able to retain moisture in their microclimate that is associated with those taller canopies – much better than the younger forest types. That also makes those forests more resilient to fire.
And so while climate change does have an impact on those forests and certainly the owls, the owls are largely affected by the weather in terms of their reproductive patterns. I think that the older forest types do serve as some resiliency towards climate change in the landscape as well.
TCA: In your study, you noted that barred owls are larger and they outcompete spotted owls. You also refer to the fight to keep the northern spotted owl from extinction difficult, costly and ethically challenging. Could it be that this is simply an issue of survival of the fittest?
Wiens: Well, I think what we said in the paper is that what was difficult and ethically challenging was the decision to whether to engage in long term management for barred owls or not. For example, do we start to establish some reserves in the spotted owl range where we manage barred owls to control their populations to levels where we can maintain spotted owls in the environment? I think that that question is a challenging one.
Along those lines, I think something that weighs very heavily for me in thinking about that very difficult decision is that barred owls are new invasive species in the Pacific Northwest and Oregon that didn’t used to be here. They’re now in very, very high numbers, are completely saturating our forests in western Oregon, and so this isn’t a situation where it’s only about barred owls and spotted owls.
Barred owls are impacting many other native species and native wildlife and the environment now. We know from prey studies of barred owls that are eating a lot of amphibian species, particularly frogs and salamanders. They’re also feeding heavily on small mammal species and a lot of different bird species as well, including smaller owls. And so when you really take a step back and look at the big picture that barred owls are now a part of, you see that they’re having a big impact on the native ecosystems in the forests. And I think that that has some leverage in making decisions about potential barred owl management strategies.
TCA: This goes beyond the attempt to keep the northern spotted owl from going extinct.
Wiens: I think it is to an extent. But also that being said, we now know that protecting spotted owl habitat in and of itself is not enough to keep the species from going extinct. That some kind of barred owl management will need to happen. Otherwise, the trajectory that spotted owls are on now, even with habitat protections in place, is looking bleak.
TCA: What other issues are being worked on in your department at the USGS?
Wiens: Well, thanks for asking. In my team, we also work a lot on other birds of prey. Particularly right now, we work a lot on golden eagles and energy development and how wind energy in particular might be impacting golden eagle populations. Golden eagles have a problem of colliding with large wind turbines and wind farms, and some of these impacts can be pretty severe to eagle populations. And so a lot of our research focuses on how to have compatible wind energy development and golden eagle conservation in these landscapes, particularly as the wind energy continues to expand throughout the western U.S.,
TCA: Are golden eagles also endangered?
Wiens: They’re not an endangered or threatened species, under the Endangered Species Act. However, they do have unique protections, federal protections, under the Golden and Bald Eagle Protection Act, so they have their own federal protections under that act.
TCA: What led you to want to spend your life working with these birds?
Wiens: When I was growing up here in Oregon, my father was a university professor. He’s an ornithologist. It’s pretty well known ornithologist – John Wiens is his name. And so he used to drag me out into eastern Oregon doing his bird studies. And I think it rubbed off on me.
I think I liked the lifestyle of being out in the outdoors and researching things and figuring out how nature works. And I particularly latched on to raptors and birds of prey.
A lot of the reason for that is because they’re this large, predatory, wide ranging species that has a lot of important functions in their environment and a lot of control over many other biological functions that occur in landscapes. And so by studying raptors and birds of prey in particular, I feel that we can get a really good handle on how to manage things just to see how their populations are responding. And they kind of tell us how we’re doing.
TCA: Thank you for your time.
Wiens: Well, thank you, Sally. I appreciate your time as well.
By Sally K Lehman
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