Sporting a curved beak and a rakish headdress, the common raven has increased its numbers dramatically with human development. Today, it is a nuissance to some despite being protected by the Migratory Bird Treaty Act. (Pixabay public domain)

The common raven is becoming so common in Wyoming and the West there’s a war being waged against it.

From Nevada to Idaho to Wyoming, ravens have capitalized on human sloppiness and development to the point their numbers have tripled in the last 40 years, according to one estimate. Considered an intelligent, even sacred, bird its status today is shifting in some circles to that of a pest.

In Sublette County, several years of study help direct workers to high-priority raven nest sites on manmade structures near important sage grouse habitat. (C-M Environmental Group Inc./Wyo. Game and Fish).

Ravens feast on garbage, roadkill and even sewage, roost on power poles and nest on windmills, oil wells and other man-made structures. They muck up industrial sites, foul livestock feed and peck out the eyes of baby lambs and cattle.

They prey on threatened desert tortoise in the Mojave Desert and rob sage grouse nests of their eggs. They may have birdbrains — but they have the largest of them — and that makes it hard to chase them off or even shoot them.

In Wyoming last year the U.S. Department of Agriculture through its Wildlife Services branch killed 832 ravens. Because of their wary nature, most of the deaths — 811 — were achieved only by poisoning.

For 2014, Wildlife Services has permission to poison as many as 2,850 ravens in the state, though it’s unlikely that many will be killed.

“The raven populations have pretty dramatically increased according to the counts I’ve seen,” said Rod Krischke, Wyoming state director of Wildlife Services. In his application for a permit to kill them in 2014, he estimated 6,000 “problem ravens” in the state and called them “the most economically damaging species,” of bird in Wyoming.

Ravens cause more than $100,000 in damage in Wyoming a year, according to the 2014 poison application. WyoFile obtained a copy of the documents from the U.S. Fish and Wildlife Service through the Freedom of Information Act.

Today, Krischke and the 41 others who are allowed to kill ravens under the permit, are protecting farmers, ranchers and industrial sites, he said. His permit application provides pages of information about why ravens could be killed to also protect sage grouse.

So far, however, ravens have not been poisoned for the sake of grouse, Krischke said. But there is “a possible indirect benefit to sage grouse,” from poisoning ravens at landfills and other sites.

“Game and Fish has expressed concern about impact to sage grouse, so were including that,” in the application, he said. “They haven’t asked us to do a specific project for sage grouse. I’m just trying to be ready.”

Canny, uncanny bird

At industrial sites, raven poop slickens catwalks and can contaminate products. At the FMC trona mine and factory in Green River, for example, the company prides itself in producing certified natural, organicbaking soda.

“You can’t have raven crap in your trona,” one biologist in the area said.

Another biologist in Rock Springs provides insight into raven behavior and shows how hard it is to kill them. He published a paper in the fall, 2012, issue of Human-Wildlife Interactions.

“Conflicts caused by ravens can be difficult and frustrating,” wrote Rod Merrell who works for Wildlife Services. Firecrackers, propane cannons and lasers don’t work well in frightening them away. Taking pot shots at ravens roosting or nesting at industrial facilities, including oil and gas wells, comes with obvious peril to the shooter.

“Effigies are the most effective means to keep ravens from roosting on towers, tanks, cable trays, and other elevated structures,” he wrote. He’s tried all manner of them, from owl decoys, to buzzards and fake, dead ravens.

“I found that only a dead raven hung upside down on about 12 to 48 inches of line or wire will effectively deter ravens for long periods of time,” the paper said.

A real dead raven is required. Merrell tried three fake ones made from Styrofoam and feathers, but they lasted only a day.

“The second day, I found all three torn to pieces and left useless by the ravens,” he wrote. “I attribute this behavior to the ravens’ keen eye and sense of smell leading them to recognize that the dummies were not real.”

Raven nests like this one can only be disturbed under a permit issued by the U.S. Fish and Wildlife Service. Although considered a pest by many, the species is protected under the Migratory Bird Treaty Act. (C-M Environmental Group Inc./Wyo. Game and Fish).
Wildlife Service, Services

Wildlife Services can’t just go out and start harassing, shooting or poisoning ravens, however. Because Corvus corax is protected under the Migratory Bird Treaty Act, Krischke must apply to the U.S. Fish and Wildlife Service every year for a permit to kill them.

To be clear, Wildlife Services is an arm of the Animal Plant Health Inspection Service, part of the U.S. Department of Agriculture. The U.S Fish and Wildlife Service is part of the Department of the Interior and it has jurisdiction over rare, threatened and endangered species.

The former kills animals, the latter saves them.

In seeking its 2014 permit, Krischke had to outline other steps it takes to reduce raven numbers shy of killing them. In the Upper Green River Basin, postcards were mailed to residents explaining about trash and ravens and landfills. Landfills in the region, except one at Farson, are covered daily. The effort also includes finding and destroying nests that are built on manmade structures. Raven nests on natural features are not bothered.

A report for Wyoming Game and Fish and Sublette County Conservation District by an environmental consulting firm in Pinedale reveals the extent of such efforts one year. The goal was to destroy nests on manmade structures near important sage grouse habitat. Workers had identified 22 priority sites to be visited in April and May of 2013.

Workers for C-M Environmental Group, Inc., spent 125 man hours and drove 1,496 miles. They destroyed 14 nests with eggs, two with chicks and one nest with chicks and an egg.

Costs came down to $176 a visit for 80 visits to various windmills and towers. The percentage of sites occupied dropped from 77 percent in 2011 to 53 percent in 2013.

There’s an effort to take down non-functioning windmills and to convert others to solar power. At the same time, the number of other structures, like cell phone towers, is increasing.

The consultants couldn’t say whether the effort actually helps grouse, however, “without analyzing all of the other programs affecting sage grouse populations in Sublette County and the surrounding areas.”

A slow-acting poison

Despite these efforts, the avicide DRC-1339 is ultimately required to kill some in the unbalanced raven population, Wildlife Services says. The poison causes kidney failure and can take several days to kill a bird.

At industrial sites a variety of structures offer ravens a convenient place to nest and roost. Such “subsidies” have allowed their numbers to triple in the last 40 years, according to one estimate. (C-M Environmental Group Inc./Wyo. Game and Fish ).
At industrial sites a variety of structures offer ravens a convenient place to nest and roost. Such “subsidies” have allowed their numbers to triple in the last 40 years, according to one estimate. (C-M Environmental Group Inc./Wyo. Game and Fish ).

It usually degrades over a few days. It is said to target ravens, magpies and a few other similar species, but not much more — a characterization that’s debated by some conservationists.

The poison comes with specific instructions. Landfill sites in southwest Wyoming, for example, are “pre-baited” before the poison is put out, Krischke said.

Wildlife Services in Wyoming uses dog food as bait in some instances. Some untainted dog food is first placed on platforms and observed as ravens feed, he said. The goal is to be sure no non-target species come to the bait.

Only when that’s established, poison rules say, can DRC-1339 be put on the bait and used. The warning label for DRC-1339 requires users to collect the carcasses of dead and dying birds.

“We don’t find a lot,” Krischke said. “We put out a public notice last year … in four to five newspapers … that we were doing this project to alert people. If they observe any carcasses we come and pick them up.”

Even though the DRC-1339 label says rules require handling carcasses with scoops, “There’s not a secondary hazard issue,” he said.

Despite laboratory studies, that assertion and the narrowness of affected species is contested. The Animal, Plant Health Inspection Service’s own literature admits to uncertainty.

“The sensitivity of non-target species to DRC-1339 is not as clear as what is observed for target species,” states an undated APHIS paper that quotes studies as recent as 2003. Barn owls, for one, are sensitive to the poison. “According to the U.S. EPA’s terminology, DRC-1339 is moderately toxic to even the least sensitive species,” the paper said.

Such information causes consternation at the American Bird Conservancy (ABC), a Washington, D.C.-based conservation group, according to an internal report prepared by Cynthia Palmer, pesticides and program manager for the group. She’s working with federal regulators at the EPA on a years-long project to strengthen protocols used when spreading the poison, hoping a more formalized checklist or documentation with signatures is required for applications of DRC-1339.

Other groups, like WildEarth Guardians based in Santa Fe, New Mexico, are more critical. It has called for abolition of Wildlife Services.

“Wildlife Services cannot document how many birds it actually kills using DRC-1339,” the group says in a position paper. “The agency’s own researchers indicate that models – not actual data – project how many birds they kill per year. Despite Wildlife Services’ assurances to the contrary, WildEarth Guardians remains concerned about the potential for non-target species to be killed by this toxicant, the decline in native bird populations across the U.S., as well as secondary poison threats to wildlife and to people’s pets.”

DRC-1339 has been used in a study in Nevada to kill ravens that rob sage grouse nests. But a plan to use it across Idaho in another program, characterized as a study, stalled in the face of opposition. Protests were based largely on failures of the proposal to follow requirements for pre-bating. A coalition of conservation groups, including ABC, joined in opposition.

Ravens roost and perch on a variety of manmade structures, like these in Sublette County, enabling them to reside in areas they used to be mainly seasonal visitors. (C-M Environmental Group Inc./Wyo. Game and Fish ).

There’s great danger in using DRC-1339 widely, said Todd Tucci, an attorney with Advocates for the West, a public-interest law and policy firm that also worked against the Idaho plan. “It’s only going to take one or two mistakes for this to be a disaster,” he said.

“Wildlife Services is bombing ahead right now,” Tucci said. While the agency may be using the avicide according to regulations in Wyoming, “They should slow down.

“Gov. Mead wants to say, ‘look at all the great things I’m doing to protect sage grouse,’” Tucci said.

Across Wyoming, there’s trepidation about what could happen to industry and agriculture if the Fish and Wildlife Service lists the sage grouse as threatened or endangered by a September deadline next year. Wyoming Game and Fish has written Krischke saying they’re looking at whether use of the poison might benefit sage grouse, Krischke said.

Sweetwater County commissioners worry about possible federal protection of the sage grouse, and so the effect of ravens on them. In a 2011 resolution, they said 70 percent of the county’s ad valorem tax base is derived from the mineral industry that exploits public land where the bird lives.

“Until sufficient effort is put forth to control predatory bird species, which feed on greater sage grouse eggs, greater sage grouse populations will continue to decline…” the resolution states. “The increase in predation appears to correlate with the relatively recent increase in the raven populations in Wyoming,” commissioners said, seeking control of ravens that are targeting grouse.

Wildlife Services agrees. “The expansion of ravens within greater sage grouse habitat likely has more impact on sage grouse numbers than the actual impacts of oil development,” the agency said in its 2014 application to poison.

Not everybody sees the relationship between grouse and ravens as so simple. Grazing, for one, reduces understory and cover for grouse nests. Whether predation is a major detriment to grouse also is unsettled science.

“The USFWS’ own 2013 Conservation Objectives Team Report ranks predation (by all predators, not just ravens), as threat number 17 (out of 18) to Greater Sage-Grouse populations,” conservation groups wrote to the U.S. Fish and Wildlife Service director in opposing the Idaho poisoning project. Also, predator control is usually short-lived.

“Raven removal in northeastern Nevada resulted in only short-term reductions in raven numbers,” a U.S.G.S. paper says, citing a 2007 study by lead author Peter Coates. “Any benefits to sage-grouse populations were negated by an increase in badger predation.”

Researchers have used video cameras to document ravens stealing sage grouse eggs. A plan to distribute poison eggs across Idaho to kill 4,000 ravens ran into stiff opposition before being abandoned this spring. (Peter Coates)

Nevertheless, there may be places where habitat quality is low and fragmented and manmade structures abound to the point that poisoning ravens may benefit sage grouse, the report says.

An ongoing study in the Bighorn Basin seeks to find out what factors, including raven densities, affect sage grouse survival, Krischke said. Some information is in and he included it in his application to poison ravens.

Three years of data from trail cameras, ground telemetry and nest inspections show ravens as “significant predators,” of sage grouse nests, the application states. “Over the course of this study, approximately 75 percent of nests have been depredated, and up to 70 percent of sage grouse chicks up to 35 days of age have been impacted by predation,” the application states.

Whether that’s significant enough to begin poisoning ravens solely for the sake of grouse hasn’t been determined. “We don’t have a definitive answer right now,” Krischke said.

Angus M. Thuermer Jr.

Angus M. Thuermer Jr. is the natural resources reporter for WyoFile. He is a veteran Wyoming reporter and editor with more than 35 years experience in Wyoming. Contact him at or (307)...

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  1. Excellent article, Angus, thanks. The same approach is being taken in Idaho, where, in place of science or valid studies of the various impacts on grouse populations, the Legislature in its infinite wisdom, has authorized the killing of up to 4,000 ravens. Yes, by Wildlife “Services”. What a euphemism. All, really, to avoid taking a hard look at loss of habitat, the basic problem that’s not going away.

  2. The increase in ravens in our little area of Montana began with a l48,000 acre fire in l984. We simply did not have them prior to the fire. We have never sprayed our sagebrush, but the fire opened areas of grass land, then the neighbor plowed up several sections of sagebrush to plant wheat thanks to govt subsidies, and the final problem for sage grouse occurred when another large ranch with lots of sage sold, and the new owners viewed sagebrush as hindering grass production, burning their sage and some of ours as well. Taken all together I would estimate that in this area about 75% of the sage habitat has disappeared due to natural or man made causes. When sage disappears here, the mountain blue bird also become scarce.

    I wouldn’t say that cows were to blame for any of the losses, but man’s greed, one way and another.

  3. The published literature suggests raptors and corvids have a limited impact on greater sage-grouse populations. I hope Wildlife Services will not shortly propose killing golden eagles and other raptors to ‘protect’ sage grouse. The numbers of predatory species increased in large part because of human activities, such as how trash is handled and where power poles are placed. If Wildlife Services has convincing data that killing ravens has a long-term positive impact on sage-grouse populations, let’s see it. USFWS has exhaustively listed the reasons for sage-grouse declines: There is little disagreement on the proximate threats. They are habitat fragmentation from agriculture, urbanization, increased fire frequency, invasive plants, and energy development.

    See: file:///C:/Users/DOT/Downloads/B06W_V02.pdf

    Killing ravens with starlicide (3-chloro-p-toluidine hydrochloride) is a more-than-usually pointless. It puts non-target species at risk from primary and secondary exposure. It kills ravens and other species, such as red-winged blackbirds, that many of us enjoy seeing as part of our heritage as citizens of Wyoming.

  4. As mankind continues to alter natural ecosystems; unintended consequences will continue to plague the natural world. Whether it is the importation of invasive species, the degradation wildlife habitat from energy production, or the expansion of ravens into heretofore unreachable sagegrouse habitat…all have negative unintended consequences. We ALL have the responsibility to try to mitigate these negative effects. Their is blood on ALL our hands. We cannot shrink from our responsibilities of mitigating these impacts; nor can we hide behind a position or ethos. We must do what we can. No one is “green” or “Environmentally correct”. Control the ravens, spray the weeds, pay more at the pump, etc. We Are the problem….We have to be the solution.

  5. Having studied western raven (Corvus corax sinuatus) breeding pairs and their territories since 1984 in Eastern Oregon, California coast, and Baja California, I have also watched the decline of sagebrush habitats due to cattle grazing and the reluctance of public land management agencies to own up to that major factor as the main cause of the decline of sage grouse populations. In Oregon they are still killed for sport. I know that in a natural ecosystem a raven pair keeps their territory free of vagrant raven flocks, an area of an average mile or more in radius. I have consulted with Dr. Bernd Heinrich for 20 some years about social flocks of immature and non breeding ravens. Therefore I view all state and federal statements regarding excessive raven predation of sage grouse with a very jaundiced eye. Especially in cattle grazing areas of public lands.

  6. Sounds like something Wildlife Services cooked up to justify their existence as an agency. I wonder if this will be as (non) effective as their coyote “control” efforts. It would be interesting to see how many tax payers dollars have been spent to “correct” a problem that we humans created and that we could fix with a little effort. We suck at playing God, especially in matters of Nature.

  7. Interesting article. Seems the issue is garbage not the critters that live off of it. Take away the food source and their populations will decline. Every time we try poisons we wind up poisoning pets, livestock, wells, and sometimes our kids. Ravens do have some natural predators but we have been tough on owls, eagles, and coyotes as well. Government attempting to tinker at being Mother Nature does not seem an effective solution and almost invariably leads to the need for a solution to undo the harm created by our initial steps and so forth.