Mexican gray wolf population surpasses 200 for the first time since recovery efforts began

For the first time since efforts began to reintroduce the species into the wild, the number of Mexican gray wolves in Arizona and New Mexico has surpassed 200, with at least 241 wild wolves documented in 2022. Of those, 105 were counted in eastern Arizona.

This year’s count, released Tuesday, is up 23% from 2021, when the population minimum was recorded at 196. This marks the seventh consecutive year of population growth and a more than doubling in size since 2017, as interagency recovery and conservation work continue.

“This milestone has been 25 years in the making,” said Brady McGee, U.S. Fish and Wildlife Service Mexican wolf recovery coordinator, in a news release. “To go from zero wild Mexican wolves at the start to 241 today is truly remarkable. In 2022, we recorded more packs, more breeding pairs, and a growing occupied range, proving we are on the path to recovery. These achievements are a testament to partner-driven conservation in the West.”

Allison Greenleaf, a field biologist with the Fish and Wildlife Service who helped conduct this year’s count, has been working with the wolves for the past 15 years. She says this year's count means recovery efforts are taking the species in the right direction.

“That 23 percent growth is really high, and we're optimistic that it’s going to keep growing and growing until we get to the point of reaching that 320, which puts us in the arena for delisting,” she said. “So we're getting closer every year to that goal, and this year was a great show of that."

Recovery plan includes annual count

The Mexican gray wolf is the rarest subspecies of gray wolf in North America and was federally listed as endangered in 1976. The Mexican wolf recovery team was formed three years later by the Fish and Wildlife Service, which developed a recovery plan for the species that called for reestablishment of at least 100 wolves in their historic range through a captive breeding program.

At the time, only seven wolves remained in existence. The wolves were reintroduced to the wild for the first time in 1998.

Since then, an interagency field team, composed of officials from the Fish and Wildlife Service and both the Arizona and New Mexico game and fish departments, has gathered information and conducted yearly counts on the wolves to track recovery efforts. The team uses a variety of methods to measure the population from both the ground and the air, including remote cameras, scat collection and visual observation.

Ground monitoring begins in November, when experts set out on foot to try to get eyes on radio-collared packs. There were 109 collared wolves in the wild at the end of last year, which accounts for 45% of the entire wild population. 

“We get a telemetry signal and do a triangulation to pinpoint where the animal is and, generally, we will hike out and try and get eyes on the rest of the members in the pack,” Greenleaf said. “If you get some good tracks in the mud or snow or traveling down the road, you can get a good count that way as well and it’s pretty accurate.”

Getting a visual count on uncollared wolves can be more difficult because of the animal's strong sense of smell. Greenleaf says the scent of humans can spook the wolves away from the field team operations.

But the team has learned to use the wolves' strong sense of smell, critical for hunting, to their advantage. The team sets up trail cameras and will lure the wolves into the frame by using a makeshift "scent station" that is abundant in fatty acids.

“We’ll use some nasty smelling stuff that canids think are amazing, and they will stop in front of the camera, and we can get a count that way as well,” Greenleaf said.

In January, the team takes to the air, via helicopter, to count the wolves through visual spotting led by the telemetry equipment. They will use the highest number from either the ground or aerial count to establish a minimum count for any given pack.

“The road to recovery for any endangered species is neither straight or easy, and this has proven to be the case for the Mexican wolf,” said Jim deVos, Arizona Game and Fish Department Mexican wolf coordinator, in a news release. "With the stunning growth that occurred in 2022, recovery has accelerated at an amazing rate."

Survival of pups boosts numbers

A minimum of 59 packs were documented at the end of 2022, with 40 of those packs counted in New Mexico and 19 in Arizona. Of those packs, at least 31 were breeding pairs, which are defined as a pack that consists of an adult male and female and at least one pup from the year surviving through the end of the year.

An impressive 121 pups were born in 2022, with at least 81 surviving by the end of the year. The 61% survival rate for the pups is also higher than the average of 50% for the species, likely due to increased genetic diversity thanks to the greater share of breeding pairs.

In addition to strong growth rates across the board for the species, mortalities have plunged this past year, with only 12 recorded deaths, the lowest number since 2017. The field team documented 25 deaths in 2021 and 29 in 2020.

Greenleaf says that additional breeding pairs have been fundamental in the population growth for the species in recent years. She hopes the trend will continue on the road to delisting the species and increasing genetic diversity.

“With the new packs that have formed, theoretically, they are now going to have pups as well and become breeding pairs, so it just goes on and on," Greenleaf said. “They are starting to colonize and set up territories in new areas of the recovery area.”

Species' genetic diversity remains low

But genetic diversity remains a hurdle for Mexican gray wolf recovery, according to Greenleaf. And despite the highest-ever population count, conservationists are concerned that recovery is still hindered by a lack of genetic diversity.

“More Mexican gray wolves surviving in 2022 is howling good news,” said Michael Robinson, a senior conservation advocate at the Center for Biological Diversity in a news release. “But with nearly all southwestern wolves as closely genetically related to each other as siblings, the Fish and Wildlife Service can’t pretend these animals are approaching recovery.”

The center says genetic diversity in the Southwestern wolves remains one of the lowest rates of almost any animal population in the world. The advocacy group believes the low genetic diversity is due to previous government and private killings. There have also been unexplained disappearances of more genetically diverse wolves released from captivity.

Greenleaf says part of recovery includes increasing genetic diversity so the wolves can achieve a self-sustaining population. She says they have found success in cross-fostering young pups.

The field team will take genetically valuable captive-born pups that are less than 10 days old and place them into a wild wolf den with pups of the same age. The wolves will then be raised as wild and, in turn, increase genetic diversity of that pack. If all goes well, pups will be documented later in the season and then collared and tracked for life.

But the center believes that sending pups into the wild without their parents is a death sentence for the endangered species. Only two of the 11 captive-born wolf pups released during 2022 into dens of unrelated wolves are known to be alive. Of the 83 total captive-born pups released since 2016, just 14 were known to be alive in 2022.

“Celebrating population growth while ignoring genetic stagnation is shortsighted,” Robinson said. “It’s time the agency resumed releasing well-bonded wolf families in which parents are usually successful in keeping pups alive to pass on their precious DNA.”

In addition to the minimum wild population, there are approximately 380 Mexican wolves currently maintained in more than 60 facilities throughout the United States and Mexico through the Mexican Wolf Species Survival Plan.

Jake Frederico covers environment issues for The Arizona Republic and azcentral. Send tips or questions to jake.frederico@arizonarepublic.com.

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