Washington state has the remaining five members of a pack of gray wolves in its gun sights this week, after assassinating six members of the pack for killing cattle that a local rancher had sent to graze atop their den.

"This wolf family has been shattered by the loss of the breeding alpha female and five other members. All that's left is an adult male and a few four-month-old pups."

—Noah Greenwald,

Center for Biological Diversity

"It's been a sickening week in the Pacific Northwest," writes Noah Greenwald, the endangered species program director for the Center for Biological Diversity. "Snipers, including gunners in helicopters, have snuffed out half of Washington state's Profanity Peak wolf pack and have put the rest of the pack in the crosshairs."

"This wolf family has been shattered by the loss of the breeding alpha female and five other members. All that's left is an adult male and a few four-month-old pups," Greenwald adds.

The state is proceeding with the extermination program despite research showing its ineffectiveness and vocal protests calling on authorities to protect the wolves, which were on the endangered species list until 2013.

The pack being targeted represents a full 12 percent of the state's gray wolf population, according to Greenwald.

This is the fourth time that the state's Fish & Wildlife Department has killed wolves to protect Len McIrvin's cattle, the Seattle Times reports, and it's the first time that the department has targeted an entire pack, according to Reuters.

Local researchers report that photographs prove McIrvin herded his cattle to graze on land directly atop the pack's den, notes the Seattle Times.

"This livestock operator elected to put his livestock directly on top of their den site; we have pictures of cows swamping it, I just want people to know," said Robert Wielgus, director of the Large Carnivore Conservation Lab at Washington State University, to the newspaper.

The Seattle Times reports:

The cattle pushed out the wolves' native prey of deer, and with a den full of young to feed, what came next was predictable, Wielgus said. After the wolves repeatedly killed McIrvin’s cattle, the Washington Department of Fish & Wildlife, as per its protocol, authorized shooting wolves in the pack by helicopter, killing the pack’s breeding female by mistake. The department then stopped the killings after the wolf predations subsided. But the department announced Saturday that after more cows were killed, it would eliminate the entire Profanity pack. That killing is ongoing, and department staff killed four more wolves this week, bringing the total to six. The department targeted the Wedge Pack after McIrvin lost cattle to that pack, near the same area. McIrvin has refused to radio-collar his cattle to help predict and avoid interactions with radio-collared wolves, Wielgus said. He called the killing of cows by the Profanity Peak pack at their den site predictable and avoidable.

Moreover, as the Center for Biological Diversity noted Thursday, a comprehensive review of the latest research found that killing predators such as gray wolves has little to no effect on livestock deaths—and it may even make the problem worse.

The study published in the Frontiers of Ecology and the Environment "shows that not only is Wildlife Services' annual killing of tens of thousands of wolves, coyotes, bears, bobcats, cougars and other animals unconscionable—it's also ineffective," said Michael Robinson of the Center for Biological Diversity. "Our government should ground the aerial snipers, pull the poisons and remove the steel leghold traps in response to these findings."

"The unexpected finding that carnivore killings can increase depredations is likely based on disruption of the predators' social dynamics," the Center for Biological Diversity observes, "namely, by removing dominant animals that maintain large territories, these killings release sub-adult animals that are less-skilled hunters and thus more likely to target domestic animals."

The conservation group argues for the state to force ranchers to take non-lethal measures to avoid livestock deaths, such as moving their cattle to other areas of public land far from wolf pack den sites, instead of assassinating rare predators like wolves.

"If non-lethal measures are not used to reduce the risk of losing cattle in the first place," Greenwald writes, "than the whole vicious cycle is likely to repeat itself once more wolves move back in. And what incentives do ranchers have to change their practices if the state comes in and kills wolves at taxpayer expense every time they start losing cows?"