BAKER CITY — Employees from a federal agency used poisoned chicken eggs to kill about 50 ravens east of Baker City last year, and the agency is authorized to kill as many as 400 of the birds this year as part of an effort to protect another avian species, the sage grouse.

This year, the last in a four-year experiment, U.S. Wildlife Services, acting on behalf of the Oregon Department of Fish and Wildlife, can use poisoned eggs or meat to kill ravens, or shoot the birds.

The permit, which the U.S. Fish and Wildlife Service issued to ODFW, also allows Wildlife Services employees to destroy as many as 100 raven nests in or near sage grouse habitat.

Biologists from ODFW and Oregon State University are studying results from the first three years but they have not published any conclusions about whether killing ravens and destroying their nests is helping sage grouse recover from a significant decline in population in Baker County.

They will continue to analyze data collected over the four years, said Brian Ratliff, district wildlife biologist at ODFW’s Baker City office.

The four-year experiment is within the Baker Priority Area of Conservation — PAC — for sage grouse. It covers about 336,000 acres, all east of Interstate 84. The PAC extends north to near Thief Valley Reservoir, east to the Love Reservoir area about 20 miles east of Baker City, and southeast to near Durkee.

The poison used to kill ravens, known as DRC-1339, is especially toxic to ravens and other corvids, which include crows, jays and magpies, but has little to no effect on other birds, such as hawks and eagles, or on mammals, Ratliff said.

According to the Fish and Wildlife Service’s March 2021 decision allowing ODFW to kill ravens — the state agency needed a permit because ravens are protected by the 1918 Migratory Bird Act — “the risk of exposure to non-target birds is low because bait sites will be monitored. Any incidental take of corvids (or other scavengers) are likely to be very few or non-existent and there not have any significant effect on local populations.”

Ravens and sage grouse

Biologists have been interested in the possible link between ravens and declining sage grouse populations in Baker County for many years.

Between 2006 and 2016, the population dropped by an estimated 73% in Baker County, based on ODFW surveys.

More recently, in a September 2023 report, ODFW stated that sage grouse populations in the BLM’s Baker Resource Area, which includes Baker County, appear to be “stable” over the past five to eight years.

The chicken-size bird has been a candidate for protection under the Endangered Species Act for more than a decade.

The U.S. Fish and Wildlife Service declined, in 2015, to list the bird as threatened or endangered.

Baker County accounts for less than 10% of Oregon’s sage grouse habitat, and 3.5% of the state’s population, according to ODFW.

Most of Baker County’s sage grouse population is east of Baker City and in the Unity area.

The bulk of the birds in Oregon, however, are in the southeast part of the state, including Malheur, Harney and Lake counties.

In looking for reasons for the plummeting population in Baker County, biologists cited studies in Nevada which showed that ravens, which eat sage grouse eggs and chicks, can have a substantial effect on sage grouse populations.

The research suggests that ravens pose a particular threat when their population densities exceed 0.7 birds per square kilometer during the sage grouse nesting spring in the spring, according to ODFW.

Other studies, according to an ODFW document that was part of the agency’s application for the federal permit allowing the killing of ravens and the removal of nests, have shown that sage grouse nesting success, and the number of birds at breeding sites, declined when raven densities exceeded 0.2 birds per square kilometer.

During April and May of 2016, ODFW surveyed sage grouse habitat in Baker County for ravens and calculated a preliminary population density estimate of 0.89 ravens per square kilometer — almost 29% higher than the threshold cited in the Nevada research.

Later surveys from 2017-19 yielded an estimated raven density of .44 per square kilometer.

ODFW estimates the raven population in the Baker PAC was about 600 birds before the four-year project started.

The 2016 survey prompted ODFW to apply for a federal permit to kill ravens and destroy their nests.

The concept was controversial.

Opponents, including The Humane Society, Oregon Wild and the Portland Audubon Society (recently renamed as the Bird Alliance of Oregon), argued that poisoning ravens was not an appropriate way to try to help sage grouse and that there wasn’t sufficient evidence that the tactic would work.

Fish and Wildlife Service officials disagreed.

In the document awarding the raven-killing permit to ODFW, Michael Green, acting chief for the federal agency’s Migratory Birds and Habitat Program, wrote that sage grouse in Baker County “would likely benefit” from reducing raven populations.

An ODFW document cites research which showed sage grouse nesting success increased after raven densities were reduced from 0.40 to 0.45 per square kilometer to about 0.25.

Joe Liebezeit, assistant director of statewide conservation for the Bird Alliance of Oregon, said on Thursday, April 4 that the organization continues to oppose the ODFW policy of killing one native species — ravens — with the putative goal of helping another — sage grouse.

“We just don’t feel like the science was there to back up killing ravens to protect sage grouse,” Liebezeit said.

He said the organization also objects to killing ravens on “ethical grounds.”

Liebezeit said multiple factors likely have contributed to the significant decline in sage grouse populations in Baker County over the past two decades or so, including livestock grazing and invasive weeds.

He said the organization sometimes endorses nonlethal methods, such as removing raven nests.

Liebezeit said that although he understands it will take years to assess whether killing ravens helps sage grouse recover, he believes ODFW has an obligation to the public to report any preliminary findings about the benefits of the experiment.

Targeting nests for two years

For the first two years of the project, 2021 and 2022, Wildlife Services destroyed raven nests but didn’t poison or shoot any birds, Ratliff said.

The tactic was largely fruitless, he said, because ravens “are really good at renesting.”

In some cases birds rebuilt nests twice, Ratliff said.

In 2023, the first year Wildlife Services distributed poisoned eggs near raven nests, Ratliff said workers targeted 18 nests where there was documented evidence, in the form of sage grouse egg remnants, that ravens from that nest had eaten sage grouse eggs.

Poisoned eggs were also set near raven nests within two miles of a sage grouse “lek” — the areas where birds gather each spring during the breeding season.

Before setting out poisoned eggs, workers placed untainted chicken eggs near the nests along with remote cameras, Ratliff said. If ravens took the eggs, Wildlife Service employees returned to place poisoned eggs.

If birds other than ravens took the eggs, then workers didn’t put out poisoned eggs to avoid killing species other than ravens, Ratliff said.

The poisoned eggs killed an estimated 49 adult ravens, he said.

(The permit for 2023 authorized killing up to 400 ravens.)

The figure is based on past research, using the same technique, which showed that on average, one raven was killed for every 10 eggs distributed, Ratliff said.

Wildlife Service workers placed 490 poisoned eggs in 2023.

Ratliff said employees did find raven carcasses near some nests, but the figure of 49 birds killed is an estimate based on the 1 to 10 ratio.

The dead birds were destroyed to prevent scavengers from eating them and potentially being poisoned.

Last year’s project also showed that ravens in some cases cache eggs rather than eating them immediately, Ratliff said.

Because the poison dissipates within a few days to nonlethal levels, those cached eggs won’t kill ravens, he said.

This year, the federal permit also allows Wildlife Services workers to place meat injected with the same poison.

Ratliff said ravens eat meat almost immediately rather than caching it.

The 2024 permit also allows employees to shoot ravens.

Mike Widman, a Baker County cattle rancher whose property includes several breeding sites, where birds gather in the spring, said removing ravens should be the “number one priority” in the effort to help sage grouse populations recover.

“We see the ravens — they’re a very smart bird and will take the easiest meal they can find,” Widman said. “They’re terrible.”

Widman said he strives to take care of his rangeland, including controlling noxious weeds that can degrade sage grouse habitat.

The birds, as their name implies, rely on sagebrush both as protection from predators and as food. Sage grouse also eat other plant seeds as well as insects.