In the News: Mexican gray wolf population grows by 24% in the 2019 survey
The number of Mexican gray wolves in the wild grew by 24% in 2019, according to the annual survey of the endangered predators.
But environmentalists and some wildlife biologists are concerned that the wolves are still subject to the effects of inbreeding, and called for more releases from captive adult families in addition to the current release practice, in which tiny pups from captive dens are cross-fostered with wild mothers.
The U.S. Fish and Wildlife Service and the Arizona Game and Fish Department, the two agencies responsible for the recovery of the wolf in Arizona and New Mexico, said the annual count found at least 163 wolves in the wild. Last year's survey found 131 wolves.
In the 2019 count, 76 wolves were found in Arizona and 87 in New Mexico, according to the Interagency Field Team, which includes the agencies and private entities in the Species Survival Plan. The team documented 42 packs distributed in the gray wolf recovery area.
The wolf release program began in 1998, and the population has increased an average of 15% for the past 10 years.
Even more encouraging, the team said 90 pups were born in 2019 with at least 52 surviving their first year. That's a 58% survival rate, higher than the average pup survival rate of 50%.
One factor that cheered biologists and other wolf recovery workers: Just 14 wolves were found dead in 2019, a decrease of 33% over 2018, when 21 deaths were reported.
"We're happy to see progress in the growth of the wolf population," said Aislinn Maestas of the Fish and Wildlife Service. "We’re working toward our recovery goals, and we see population growth is progress toward reaching our ultimate goal."
That goal, according to the wildlife service's 2017 recovery plan, is for two gray wolf populations to average 320 over an eight-year period and to achieve sufficient genetic diversity in the species so that 22 wolves released into the wild grow to adulthood at age 2, when they are of breeding age.
The genetic diversity goal is key to the gray wolf's long-term survival, since the entire species population, which includes the wild population and about 300 canids that live in captivity, is descended from just seven wolves.
Concerns about the wolf's genetics
Although he's glad to see the population increasing, Michael Robinson of the Center for Biological Diversity is still worried about how closely related the wolves in the wild are.
"Inbreeding is still a problem," said Robinson. "It's not nearly enough resolved by cross-fostering."
He said each wolf born in the wild is as closely related as if they are siblings. Without a greater infusion of fresh genes from the captive wolves, Robinson said, the wolves will experience physiological problems like general unfitness and reduced resistance to diseases.
Robinson recommended a return to releasing entire wolf families, known as packs, from captivity into the wild. However, he said, the "shotgun marriage" approach to releasing adult pairs doesn't work, as the pairs haven't yet bonded and they usually go their separate ways.
Instead, he said, "leave the wolves paired for at least six months to a year before sending them out so they'll stay paired."
Robinson said the cross-fostering program isn't nearly as effective.
"Just two out of 12 pups being known to be alive from 2019's release isn't a good number," he said, although he acknowledged that nobody knows for sure since the surveys can't count every single wolf. Robinson said the current release program will result in only a "medium-term survival" of the wild population.
Wildlife biologists Phil Hedrick and Rich Fredrickson agreed that the wild gray wolf population is on the increase.
But, they said, "without genetic information and analysis, it is not possible to determine whether the increase in numbers has a positive or negative effect on genetic variation and inbreeding depression."
In the emailed statement, Hedrick and Frederickson added that it's hard to say when inbreeding will lead to declines in wolf fitness levels that could imperil their survival, because in large part, more than half of the packs are artificially fed during the spring and summer seasons.
"This artificial environment increases pup survival relative to packs that are not fed, thus masking the potential effects of any inbreeding accumulation," they said.
And, they added, they observed that the same packs are fed year after year, which they feel could accelerate inbreeding to the eventual detriment of the wild population.
"The big question is what happens after artificial feeding is discontinued in the future," the biologists wrote. "We don't think the wild population will suddenly collapse but we may eventually see a reduction in growth, followed by no growth or even a decline in population. However, if the feedings stop now, we think that the population would experience a sudden drop."
Wildlife agencies say cross-fostering works
Jim deVos of the Arizona Game and Fish Department disagrees with that assessment.
"The calls for adult releases don't understand the science behind cross-fostering," he said. "Each year, the organizations and agencies participating in the gray wolf's Species Survival Plan meet to match wolves listed in the studbook."
That's the genetic record kept of every wolf, both living and dead, that the survival plan agencies use to breed captive wolves.
"We know about how many pups are going to be born that year," he said.
DeVos added that despite wolf conservation centers' best efforts, adult gray wolves are essentially no longer wild, and that causes problems when they are in the wild.
"The data say that the released adults get into trouble by going around people, and not hunting elk or other wild game like they're supposed to," he said.
Maestas, of the federal agency, and deVos added that New Mexico's reentry into the wolf recovery program will contribute to the success of the cross-fostering program.
DeVos said the Arizona Game and Fish Commission has capped the number of released pups at 12, but now that New Mexico is back as a partner, the cross-fostering program can increase that number.
Both Maestas and deVos said they weren't certain why the mortality rate had declined in 2019, but deVos has a theory as to one possible reason.
"Last fall we reached out to every hunter," he said. The outreach and education program involved letters sent to hunters urging them to take a second look when they think they have spotted a coyote, especially in eastern Arizona where the wolves are being managed.
And deVos said he feels much of the initial resistance by local ranchers and residents to wolf releases has subsided.
Maestas said Catron County, New Mexico, long a holdout to wolf releases, has joined the conservation effort. And deVos said he senses a decrease in environmental resistance to the recovery effort.
"It's been a while since I felt like I had to sit in the last chair because I might have to leave fast" due to threats, he said.
Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic environmental reporting team at environment.azcentral.com and @azcenvironment on Facebook, Twitter and Instagram.
Reach the reporter at debra.krol@AZCentral.com or at 602-444-8490. Follow her on Twitter at @debkrol.