SILVER CITY, N.M.— The population of endangered Mexican gray wolves in Arizona and New Mexico grew by 10 animals last year, from 186 animals in 2020 to 196 in 2021. While this represents an overall increase, the pace of recovery is being hampered by illegal killings, disease, and genetic mismanagement.
“It’s worrisome that so little’s known about why Mexican wolf population growth is slowing,” said Michael Robinson, a senior conservation advocate at the Center for Biological Diversity. “I’m concerned that high pup mortality is part of the problem. Rather than putting pups into unrelated wolves’ dens, moms, dads and pups should all begin new lives in the wild together.”
The small population increase came despite last year’s releases of 22 captive-born pups into the dens of unrelated wild wolves in an effort to restore lost genetic diversity. Between 2016 and 2020, 50 other captive-born pups were similarly released. Of these 72 pups released by the U.S. Fish and Wildlife Service, just 14 are now known to be alive in the wild.
A 2007 study showed that low levels of genetic diversity correlated with lower reproductive success in Mexican wolves.
Population growth in 2021 was dampened by the customarily high removal and mortality rate. The federal government removed 10 wolves alive from the wild in 2021. Twenty-five GPS-collared wolves died. Several other collared wolves disappeared, as did many of the released pups who were too small to be outfitted with collars.
Among other wolf deaths in 2021, the Cerro Trigo pack in Arizona first lost a pup and later both adults; the pack no longer exists. No causes of death have been reported, but most known mortalities end up being classified as illegal killings years after they occur.
The Service is under a court order to amend its recovery plan to include a strategy to decrease the number of wolves killed illegally. Scientists and conservationists have urged the agency to retrieve telemetry receivers loaned by the government to livestock owners, two of whom have pled guilty to illegally killing Mexican wolves.
Though most other causes of death were not reported, the Service disclosed that two wolves in 2021 died of canine distemper.
One storied wolf, Mr. Goodbar, traveled to the border wall in New Mexico in 2021, then back north, where he was shot and had his leg amputated this year. Having now recovered, he has roamed dozens of miles through the Gila National Forest and nearby public lands.
“Even though the wolves show grit, determination and intelligence, that may not be enough to save them,” said Robinson. “I’m afraid that without a more serious federal commitment to science-based management, wolf numbers will stagnate and genetic problems will multiply.”
Mexican gray wolves are a genetically and morphologically unique gray wolf subspecies native to Mexico and the southwestern United States.
The U.S. government exterminated wolves in both nations on behalf of the livestock industry in the 20th century. The subspecies was saved following the 1973 passage of the Endangered Species Act through live capture and successful breeding of six wolves from Mexico and one from Arizona.
Some of their descendants were reintroduced into the United States beginning in 1998 and in Mexico, where approximately 40 wolves survive, beginning in 2011.