Standards updated to confirm livestock killings by wolves in Arizona, New Mexico

PHOENIX — The U.S. Department of Agriculture’s Wildlife Services released a new set of standards to confirm livestock killings by Mexican wolves in Arizona and New Mexico.

The document states confirmation that a Mexican wolf was responsible for depredation requires subcutaneous hemorrhage and underlying tissue damage be present on carcasses, which would show the animal was still alive when an attack occurred. Wolves also scavenge on carrion, which has led to false blame.

Bite marks, tracks, scat, wolf movement patterns and multiple kills in one event are other forms of physical evidence that differentiate a wolf killing from other predators such as coyotes. But these alone are stated as insufficient to confirm the cause of death.

Conservation groups have praised the strengthened standards while calling on further regulations.

“It’s appalling that the U.S. Department of Agriculture blames endangered Mexican gray wolves for killing cows that died of something completely different,” Michael Robinson, senior conservation advocate at the Center for Biological Diversity, said in a press release. “I’m glad they’re tightening standards for determining the causes of cattle mortality, but the government should go further and require that ranchers properly dispose of dead cattle to protect both wolves and livestock.”

“Our goal has been to make sure that Mexican gray wolves aren’t being unfairly blamed for livestock depredation,” Greta Anderson, deputy director of Western Watersheds Project, said in the release. “The over-reported incidence of wolf involvement in cattle deaths in the Southwest has had negative impacts on the wolf recovery program, including the killing and capture of wild wolves.”

A male Mexican wolf named Rusty was killed in New Mexico by authorities in April for its alleged depredation of livestock. Environmental groups warned at the time that killing a breeding male could impact the pack’s survival.

The Mexican wolf was eliminated from the wild in the U.S. by the mid-1970s via traps, shootings and poison to protect livestock.

The species has been listed as endangered since 1976, but conservation efforts including breeding programs and cross fostering have led to an increase in wild packs in the Southwest. The wild population eclipsed 200 last year for the first time since reintroduction in 1998.

“Wildlife Services has a responsibility to not only accurately determine the cause of livestock death but also to help dispel the myths surrounding wolves and promote strategies that avoid conflicts,” Mary Katherine Ray, wildlife chair for the Rio Grande Chapter of the Sierra Club, said in the release.

Determination of depredation categories include confirmed, probable, unknown and other, which includes shootings, vehicle collisions, lightning strikes and other predators.