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BY Hayleigh Evans
Visitors squeezed into a small examination room at the Southwest Wildlife Conservation Center in Scottsdale as Cruz, a 7-year-old Mexican gray wolf, underwent his annual health checkup. The wolf slept under sedation on the exam table, and aside from the occasional twitch, appeared oblivious to the flurry of activity around him.
Veterinarian staff checked his teeth and paws, administered vaccinations and fluids and drew blood to ensure Cruz was in peak condition.
His heart monitor beeped steadily, punctuated by the clicks of photographers with their cameras as they made the most of a health exam usually closed to visitors.
Cruz’s mate, Terra, waited in a crate in the next room for her turn on the table.
To catch a glimpse of an endangered Mexican gray wolf would usually require trekking into the wilds of the White Mountains, where most of Arizona’s packs roam. The Southwest Wildlife Conservation Center offered a rare opportunity to see lobos up close.
The Arizona Game and Fish Department opened the exam as it marked the 25th anniversary of the first Mexican wolves reintroduced to the wild and to tout the program’s recent advancements.
Mexican gray wolves were nearly extinct in the wild in the 1970s, but after the subspecies was added to the Endangered Species Act list, they began a slow path toward recovery.
Terra and Cruz, known in records at F1402 and M1506, are valuable genetically diverse wolves that officials believe represent the future of the repopulation efforts. They are two of about 360 wolves in captivity, and biologists believe their offspring could contribute to the wild population.
Officials want to place more wolves in a foster program that pairs pups born in captivity with wild packs, part of efforts to diversify the gene pool and boost an upward trend in the repopulation effort.
“Terra and Cruz both have some valuable genetics, and we would like them to breed and give us some puppies,” said Dr. Anne Justice-Allen, a veterinarian for Arizona Game and Fish who led the exams. “They look healthy, but they’ve had multiple opportunities to breed and haven’t done it yet.”
The U.S. Fish and Wildlife Service, along with state wildlife agencies in Arizona and New Mexico, believe the efforts are a success as the wolf population steadily increases toward levels that would allow the federal government to remove the wolves from the endangered species list.
But while wolves are gaining numbers — last year’s count of 242 wolves in the wild was a 23% increase from 2021 — wolf advocates believe agencies should be doing more to save the imperiled species.
Those advocates want the agencies to rescind the stipulation that calls for the killing or live removal of wolves outside the recovery zone, release family packs of wolves instead of pups and allow wolves to roam north of Interstate 40 to breed with northern gray wolves, which will diversify the gene pool.
“The genetic diversity is what’s going to make or break the Mexican wolf recovery ultimately,” said Michael Robinson, a senior conservation advocate for the Center for Biological Diversity.
As the recovery program enters its 25th year, questions remain about how wolves can co-exist with people and other species, even as activists worry that too little progress is being made.
Genetic diversity:11 Mexican gray wolf pups are released into the wild. Will it help the species recover?
State points to rising population numbers
Wolves have been roaming the southwestern U.S. and Mexico since they migrated from Eurasia during the Ice Age. But after settlers arrived in the species’ natural range in Arizona, New Mexico, Texas and Mexico, the population began to dwindle.
As human activity in the region increased, wolves’ native prey decreased and the animals turned to domestic livestock to supplement their diet, which created conflict with ranchers and other people moving into the region.
With the help of government agencies, people began targeting and killing wolves to protect livestock. The wolf population declined over the decades until few remained in the wild.
“Wolves were persecuted and, in essence, absent from the U.S. by the 1930s largely as a result of eradication programs by some federal agencies,” said Jim deVos, the Mexican wolf coordinator for the Arizona Game and Fish Department.
After Mexican gray wolves were classified as an endangered species, recovery efforts began. The populations in the wild and captivity descended from three lineages in the remaining seven purebred Mexican wolves.
Biologists merged the three lineages from the original seven. Three were captured in Mexico, two came from a zoo in Mexico, and two were found in the U.S. They created the Blue Range Wolf Recovery Area, which includes parts of the Apache-Sitgreaves National Forests in Arizona and the Gila National Forest in New Mexico south of Interstate 40.
The wolves in the recovery area are part of a nonessential experimental population. State officials say the designation gives them greater flexibility to manage the population.
The first captive-born wolves were released in March 1998, and releases since then have had varying results over the last 25 years.
“We’ve had successes and problems along the way, but the last decade has been amazing for the Mexican wolf. It’s gone up in numbers every year,” deVos said.
As of the last annual count in 2022, there were 242 wolves in the wild with 32 breeding pairs. DeVos expects this year’s count will show another increase.
Habitat boundaries:Wildlife officials drew a line at I-40 for Mexican gray wolves, but has it hurt recovery?
How genetic diversity could help the population grow
Eventually, officials hope to remove Mexican wolves from the endangered species list. The state and federal agencies believe continuing the foster program is key to expanding the population in the wild and building genetic diversity.
In the captive population, the agencies monitor wolves’ genetic sequences in an attempt to create a healthy, strong and resilient subspecies.
“You want some slightly different copies of the same gene because that means there’s variability in the population. You don’t want inbreeding,” Justice-Allen said. “They’re better able to respond to changes in their environment.”
The agencies pair genetically diverse wolves, like Terra and Cruz, in hopes they will breed and produce pups. When a captive wolf becomes pregnant, biologists monitor the wild population using telemetry collars that track the animals’ location.
They match the litter in captivity with one or more litters in the wild; those litters are ideally born within five days of each other so the pups are nearly the same age.
Depending on litter size, one or two pups remain with their mother in captivity, and the rest are taken to a den in the wild. Officials ensure the pack will accept the pups as its own by scenting the newest additions.
“Everybody gets rubbed down with the same stuff, so they all smell the same,” Justice-Allen said. “The mother wolves and everybody in the pack take to them just fine. It’s a good thing wolves can’t count. Nobody notices a few extra noses in there.”
The goal is to remove the subspecies from the endangered species list and, based on the revised 2022 wolf recovery plan, there are two criteria for that action.
First, the wild population must reach 320 wolves between Arizona and New Mexico. The population must remain at a 320 average for eight years, and numbers in the final three years must be stable or increasing.
The agencies must also introduce genetically diverse adult wolves from captivity that survive for a year or pups that survive for two years. According to deVos, the agencies have released 15 pups this year that they hope will live.
As the agency prepares for its annual count this winter, deVos said he’s optimistic they could surpass 320 wolves. He believes the wolf population could be delisted in the next 15 years.
“When Congress wrote the Endangered Species Act, it was clearly their intent that animals on the list would go off,” deVos said. “The goal is to get Mexican wolves off the endangered species list to where they have a secure future on the landscape throughout its historical range.”
If the Mexican wolf is delisted, the state agencies would continue to address the stressors that hinder the population, trying to decrease illegal killings by humans, provide ample habitat and ensure a varied genetic pool.
Wolf advocates have expressed concerns that the species could die out due to a lack of genetic diversity from inbreeding and questioned current management practices, despite Arizona Game and Fish’s confidence that the wolf population will continue to rise.
For the second time in a year, a wild Mexican wolf named Asha — also known as F2754 — has left the recovery area and ventured north of the I-40 boundary.
Wolf advocate groups like the Center for Biological Diversity believe her determination to journey north justifies their demand for officials to expand the recovery area into the southern Rocky Mountains.
“Recovery is still possible, but it’s a lot less possible than 10 or even five years ago if things had been done differently,” said Robinson, who works on wolf issues for the center.
There are three things the management agencies have to do that coincide with extending the boundary to prevent extinction, Robinson said.
Advocates want the agencies to repeal the rule that requires the removal or euthanization of wolves in the wild that stray from the recovery area or have conflict with livestock.
They also believe releasing family groups of wolves from captivity instead of fostering wolf pups would be more effective in diversifying the gene pool.
Experts have found the genetic variability through the entire wild population is equivalent to just two individual wolves. The variation in the captive population is slightly better, equal to about three individual wolves.
“The genetic variation of the Mexican wolves is the lowest of any wolf population,” said Phil Hedrick, a former professor at Arizona State University who specializes in wolf population genetics and conservation biology.
Hedrick believes inbreeding within the subspecies could ultimately lead to its extinction.
By releasing entire families instead of only pups through the fostering program, wolf advocates believe there is a higher chance of introducing distinct genes from captive populations into the wild packs.
Advocates’ third strategy to ensure survival is to allow wolves to roam north of I-40 and breed with northern gray wolves. In theory, this would allow introgression — the transfer of genetic material between subspecies — and revitalize genetic variation in the population.
According to Hedrick, wolf subspecies naturally bred in the past, creating numerous subspecies between the northern gray wolf and Mexican wolves that were eventually killed or hunted out.
He says establishing two more recovery areas would prevent a complete degradation of the Mexican wolves’ genetic identity.
“Reestablishing this pattern of mixing north and south is what naturally occurred. Having a population in southern Colorado, northern New Mexico and the North Rim of the Grand Canyon would be a buffer if there was a problem of northern gray wolves coming down,” Hedrick said.
“These are all wolves, they’re all the same species,” he said.
State officials believe they should continue restricting wolves to the recovery area and releasing pups in the foster program. deVos said allowing them to wander past I-40 “really does a disservice to the wolves.”
The agencies conduct public outreach to ensure hunters, ranchers and communities know Mexican wolves are in their area.
When wolves like Asha leave the recovery area, they are more likely to be killed by hunters assuming they are coyotes or conflict with humans and livestock. Asha could be wandering in search of a mate, but she will not find fellow Mexican wolves that far from the repopulation zone.
Because Mexican wolf numbers are increasing, the Arizona Game and Fish Department sees no physical indication that it needs to introduce new genes from Northern wolves.
“We are very concerned that if a Mexican wolf goes north of I-40 and a Northern wolf comes south and they breed, we’ve lost the genetic integrity of the Mexican wolf,” deVos said. “Let’s conserve the Mexican wolf as a unique species.”
Hayleigh Evans covers environmental issues for The Arizona Republic and azcentral.