Why wildlife officials are killing some PNW owls to save others - Anlık Haber

Stripes, round bodies, dark penetrating eyes. At a glance, the barred owl and the northern spotted owl are easily mistaken for the same bird.

So what warrants protections for one and killing the other?

The U.S. Fish and Wildlife Service <a href=”https://www.fws.gov/press-release/2024-08/strategy-manage-invasive-barred-owls-protect-imperiled-spotted-owls”>finalized its Barred Owl Management Strategy</a> in August. The plan could result in killing up to half a million barred owls over 30 years to save the endangered northern spotted owl, which is at risk of extinction, said USFWS Wildlife Biologist Robin Bown, who led the Barred Owl Management Strategy team.

“Our goal is to continue to have both owls persist on the landscape,” said Kessina Lee, the Oregon state supervisor for USFWS. “Preventing the extinction of species is what we’re charged with on behalf of the American people.”

When the northern spotted owl was first listed as threatened under the Endangered Species Act in 1990, habitat loss was the primary cause of endangerment. Soon after, in the early 2000s, the invasive barred owl, which had recently migrated from the East Coast, was added as another driving factor, said Bown.

In this May 8, 2003, file photo, a northern spotted owl sits on a tree in the Deschutes National Forest near Camp Sherman, Ore. In March 2024 the Biden administration restored rules to protect imperiled plants and animals that had been rolled back under former President Donald Trump. (AP Photo/Don Ryan)

Human-mediated activities made the barred owl’s range expansion possible, said Peter Hodum, professor of avian ecology at the University of Puget Sound. A combination of direct changes like planting forests and indirect efforts like fire suppression created conditions that allowed the barred owls to expand westward, he said.

Barred owls made it to Washington in the 1970s, and their population has increased about one percent per year, pushing northern spotted owls out of their native territories, said Lee.

Barred owls easily out-compete northern spotted owls in areas where they overlap, said Claire Catania, executive director of conservation nonprofit Birds Connect Seattle. “They’re very territorial, and the barred owl’s territories can be more densely packed than a northern spotted owl. Barred owls eat a greater variety of foods than the northern spotted owls, so they can do more, consume more in a smaller area.”

The barred owl’s existence in Pacific Northwest forests is a direct threat to the survival of northern spotted owls, said Bown. It’s difficult to predict what the extinction of the spotted owl could do to our ecosystems on a grander scale, said Hodum.

Ecosystems are extremely complex, and sometimes something that seems innocuous could cause a significant impact, said Bown.

Barred owls are generalist predators that target species not threatened by owls before they came to Washington, she said.

Generalist predators are animals that eat a large variety of prey, and barred owls have a wider range of diet than northern spotted owls, said Hodum.

“We’re really worried that they could have some significant impacts on our salamanders and there’s a lot of salamanders … species that are at risk. They can also have impacts on our fish [populations],” said Bown.

People are worried that the existence of barred owls in Pacific Northwest forests could have a cascade of impacts all the way down the food chain, she added.

Forest protection

But relying on the Barred Owl Management Strategy alone to save the northern spotted owl is not sufficient, said Catania of Birds Connect Seattle.

“We have to continue to do more aggressively to protect our forests … [to prevent] further habitat destruction,” she said. “Or else this management strategy will not be successful because it is not the only ingredient required.”

In 1994, federal agencies <a href=”https://www.cascadepbs.org/2014/04/northwest-forest-plan-20-years-battles-obama”>developed the Northwest Forest Plan</a>, which guides habitat and federal land management to protect endangered wildlife and improve regional sustainability. A critical focus of the Northwest Forest Plan is to protect old-growth forests and habitat for spotted owls, said Bown.

Northern spotted owls need to reside in complex tree canopies that can support their prey and provide shelter, said Hodum, and those are usually old-growth forests that have never been logged.

“We actually were starting to see an improvement in spotted owl population trends as a result of that habitat management, not that they were increasing, but the rate of decrease was less,” said Bown.

Forests that were once logged take at least 250 years to develop the characteristics of an old-growth forest, Hodum explained.

“But out West at least, because the history of logging is only 150 or 160 years old,” he said. “We don’t have that same history as, like, the East Coast, where forests may have been cut in the early late 1600s, early 1700s, and then just left to recover. So our logged forests are going to be younger.”

Northern spotted owls don’t have a 250-year period to wait around, he said.

“We’re talking about a long time horizon. We can’t wait,” he said. “If we don’t do anything but the habitat restoration, the trajectories show spotted owls will be long gone from these landscapes before those forests mature to the point at which they’re suitable for spotted owls.”

Despite positive trends impacted by current habitat management, when barred owls moved into the ranges of spotted owls, the positive trend crashed, said Bown.

According to a <a href=”https://www.nps.gov/articles/000/nccn-nso-monitoring.htm#:~:text=Populations%20on%20the%20Olympic%20Peninsula,over%2080%2C000%20acres%20of%20habitat.”>study on Mount Rainier National Park</a>, barred owls invaded and moved into an area that has not seen forest disturbance in 120 years, and the results showed poor rates of spotted owl survival and occupancy rates, said Andy Geissler, federal timber program director for the American Forest Resource Council.

Alternative solutions considered

The ideal solution would be to prevent barred owls from arriving, but that’s not possible, said Hodum. Spotted owls and barred owls are able to access the same locations, so solutions need to involve removing barred owls, he said.

The USFWS considered a variety of alternative methods of barred owl removal before settling on killing them, said Bown.

“Unfortunately, most of the non-lethal methods just really don’t provide for a reduced population of barred owls,” she said. “Or at least one that gets reduced fast enough that you can take advantage of it.”

The USFWS also considered capturing and sterilizing barred owls.

While barred owl populations would decline eventually, it would happen only after captured and sterilized adults die off. By that time, the spotted owls would have all died, said Bown.

Another option was capturing and relocating the owls.

“We’re talking about tens of thousands of barred owls. We can’t keep them all in captivity, you know?” said Hodum. “That’s just not realistic to have facilities where we’re keeping tens of thousands of wild owls in captivity. It’s also arguably really inhumane if you’re taking wild animals and then, you know, keeping them in restricted captivity.”

Bown said relocating barred owls back to the East Coast was also considered.

USFWS contacted the state departments of native barred owl states and they were concerned about the risks of overpopulation, as their habitats were already fully occupied. They were also worried about the potential of moving the owls and accidentally bringing parasites and diseases from the West into the native population in the East, said Bown.

Numerous studies over the past 10 years in Washington, Oregon and Northern California have found that removing barred owls by killing them caused an immediate improvement in spotted owl survival, said Bown. In those areas, spotted owl population stabilized over three to four years, in contrast to other areas where barred owls were not removed and the spotted owl population decreased by 12% each year.

“We were able to run the study [on the Hooper Reservation in California] for 10 years, which allowed us to look at not just the short term, you know, movement, but whether that continued,” said Bown. “In fact, it did continue. Their populations have actually increased, not just stabilized but increased over the course of that 10 years.”

Elimination of one species to preserve another is not a new conservation strategy, said Hodum.

In the Midwest, one cause of the endangerment of the Kirtland’s warbler was brown-headed cowbirds, said Hodum. After federal agencies killed the brown-headed cowbirds, the warbler populations rebounded.

In 2019, after 40 years of brown-headed cowbird management, the Kirtland’s warbler was <a href=”https://www.fws.gov/species-publication-action/removing-kirtlands-warbler-federal-list-endangered-and-threatened-0″>officially delisted</a> from the federal endangered and threatened list. Hodum said they hope to repeat that success with the Barred Owl Management Strategy.

According to the <a href=”https://www.fws.gov/sites/default/files/documents/2024-08/final-barred-owl-management-strategy-2024_508.pdf”>official Barred Owl Management Strategy</a>, trained specialists would attract barred owls with recorded calls and shoot birds that respond and approach closely. This was evaluated to be the most humane method that minimizes the possibility of non-fatal injuries.

The Barred Owl Management Strategy is not a concrete 30-year plan; allowances are made for yearly progress reports and a reevaluation every five years. The approach would focus on certain areas with the idea of optimizing the increase of spotted owl populations.

In Washington, the USFWS would target barred owl management in areas such as the Cascade Mountain Range, the Olympic Peninsula and the Western Washington Lowlands, said Bown.

“[The goal is to] allow spotted owls to survive and thrive, but also having them spread across the landscape,” said Bown. “To [expand] the diversity of environments that they’re in, and if a fire burns through an area, we don’t lose everything. We’re trying not to put all our eggs in one basket.”

Hodum called the ethical dilemma in the Barred Owl Management Strategy a trolley problem conundrum: a choice between saving one species and sacrificing another.

“Ultimately, when we’re talking about invasive species, something is going to suffer,” he said. “Something is going to die, and in this case we have a choice, and I think sometimes what’s lost in this is that if we choose the path of no action, we are then by default choosing to let spotted owls die.”

Around 16,000 barred owls would be removed per year, and the removal at its maximum would represent half of 1% of North America’s total population of 3.5 million barred owls, said Lee.

“We shouldn’t be immune to the tragedy that the lethal management of the barred owl presents,” said Catania. “I love owls very, very much. They’re beautiful, and I am deeply saddened that this has become necessary and wish that it hadn’t, if we had done what we should have to protect our old-growth forests.”

The USFWS does not take the decision to kill barred owls lightly and strives for a future where barred and northern spotted owls can coexist, said Bown.

“If we do something now,” she said, “then we can have both species on the landscape.”

Topics: 

Source

Yorum yapın Yanıtı iptal et