Federal biologists look to boost Mexican wolf genetics
GILA NATIONAL FOREST, N.M. — On an early Monday morning, four helpless, tiny creatures that will eventually become some of nature’s top predators found themselves nestled under a commercial airline seat.
The Mexican wolf pups, removed from their mother’s den in captivity in Missouri a few hours earlier, were destined for wild dens in southwestern New Mexico.
The U.S. Fish and Wildlife Service is hopeful that this tactic, called cross-fostering, will aid in the recovery of a species that was nearly eliminated and now numbers just over 100 animals in the United States.
The primary goal isn’t to increase the wolf population, but to increase the population’s genetic diversity. This diversity is lacking because the entire current population descended from just seven wolves pulled from the wild.
The cross-fostering process is incredibly complicated and requires precise coordination by multiple agencies in the United States and Mexico.
It begins when Mexican wolves breed in February and March. The 50 or so wolf recovery facilities throughout the two countries that have observed breeding pairs will alert the Fish and Wildlife Service to potential future pups.
Females give birth to litters after 63 days and then things have to move quickly.
The captive pups and the wild litter they’ll be inserted into can be no more than a few days apart in age, all must be under 14 days old and the captive pups can’t be taken from their mother until they’re at least 5 days old.
“It’s tough to align those stars,” said Maggie Dwire, the assistant Mexican wolf recovery coordinator for the Fish and Wildlife Service.
While it’s fairly easy for the captive facilities to know when a litter has been born, their wild counterparts are a little trickier to monitor.
Using radio collars that have been placed on many of the adult wolves in the population, the recovery team will track a female’s movement, looking for signs that she may be making a den.
Once she’s been in the same spot for a couple of days, the team will assume she has had a litter.
Captive pups will be matched with potential wild dens.
In this case, four pups from a litter of eight born May 7 at the Endangered Wolf Center in Eureka, Missouri, were chosen to be placed in two dens in New Mexico’s Gila National Forest.
A long day’s journey
Regina Mossotti, the Endangered Wolf Center’s director of animal care and conservation, rises at 1 a.m. Monday and travels to the center to retrieve the pups.
She and her team extract four of the healthiest and largest pups, two males and two females, whose eyes and ears are still closed at this age. Each weighs around a pound-and-a-half.
The center has named them Orion, Cimarron, Ruby and Katie. Once they’re in the wild, the Fish and Wildlife Service will assign them identifying numbers.
From there, it’s on to the airport. The pups are stowed under a seat in a small carrying bag, their temperature closely regulated using hand warmers and a thermometer.
If the pups get too warm, they’ll move farther apart, sometimes splaying out in a spread-eagle position.
After a layover in Denver, Mossotti and the pups arrive in Albuquerque.
Mossotti and members of the Fish and Wildlife Service’s Mexican wolf recovery team meet in a dirt pulloff near the airport to check on the pups.
To the untrained eye, it’s difficult to tell them apart from dogs. They whimper and squeal like domestic puppies.
They’re tube-fed warm formula, which nearly instantly renders them still and quiet.
Then they are packed into the bag again, and it’s time to hit the road.
The destinations are in the Gila National Forest, a patch of wilderness located in the southwest corner of the state. The pups, resting in their carrying case in the back seat next to Mossotti, can occasionally be heard squeaking in disapproval after going over particularly large bumps.
Passing Socorro, the journey is now exclusively on remote, dirt roads that pass the gargantuan white dishes of the Very Large Array and the Luera Mountains.
Herds of elk, which make up most of a Mexican wolf’s diet, and cattle – which they do prey on from time to time – can be seen grazing from the road.
There were 36 confirmed cases of livestock depredation in 2017 between New Mexico and Arizona.
After hours of driving, the team meets just outside the forest to do a final health check on the pups and split them up to head to their new homes.
An agency veterinarian also injects the pups with some additional fluids, and they’re fed again to tide them over until their adoptive mother returns to the den to feed them.
Then, it’s back in the truck.
Dwire and Mossotti are heading to the Iron Creek Den. The others are headed for the Lava Den.
Even at this stage in the game, there’s still a level of uncertainty: Dwire says it’s possible there aren’t any wild pups in the den, or maybe they’ll appear unhealthy or they’re much older than the captive pups.
“But none of that is going to happen today!” Mossotti interrupts from the back seat. “Everything is going to go smoothly.”
After parking at the staging area, Dwire places the two pups in a backpack and makes the half-mile hike to the den along with biologists from Fish and Wildlife Service and the U.S. Forest Service.
Biologists who arrived first have already located and flushed the female from the den.
The female did good work; the den is long and deep in the ground.
One biologist has to shimmy into the den on her belly, and only her feet are visible as she retrieves the five wild pups found inside.
Then, the seven pups are placed on a tarp where DNA samples are collected and microchips inserted.
The wild pups are larger than expected, and certainly larger than their new siblings, but the team is heartened since the captive pups seem more coordinated.
The biggest wild pup, which Dwire dubs a “fat frat dude,” is removed from the den to reduce competition for mother’s milk.
“We opted to try to increase chances that the captive pups would do well,” Dwire said later.
He was placed in a third den with the nearby Dark Canyon pack.
The pups are then put back into the den, and the team hikes out.
A promising approach
This will likely be the last cross-fostering of the year. Four additional pups from the Endangered Wolf Center were placed in two dens in New Mexico and Arizona last month.
Dwire said her agency is hopeful that cross-fostering will be at least as effective as releasing adults into the wild.
In total, releases from captivity, including pups and adults, have a 28 percent success rate, Dwire said. Success means they survived and bred.
Of the 12 pups cross-fostered into wild litters since 2014, four are documented to have survived, with three of them having produced pups in the wild.
“If cross-fostering works as well (as adult releases), then I think cross-fostering would be preferred because then you’re not dealing with naive wolves being released to the wild,” Dwire said.
Wolves raised in captivity and released as adults typically display unnatural behaviors, at least for the first few months. For example, they’ve been documented chasing ATVs.
“Their flight response isn’t as high,” Dwire said.
Whatever recovery tools the team uses, Dwire said she hopes the population in New Mexico and Arizona will experience a larger increase than last year, when it went from 113 in 2016 to just 114 in 2017.
For now, the team has done its part, and now it’s up to the pups and their mother to stay alive.
Only about half of Mexican wolf pups survive, and wild wolves have significantly shorter lifespans than those in captivity.
The team won’t know how the Iron Creek litter fared for at least a few weeks, when the pups venture out of the den for the first time.
“Our biggest goal is to help conserve an endangered species. But we worry about these guys, too,” Mossotti said after the pups were placed in the wild den. “The wild, it’s a rough life, but it’s worth it to give them a chance at freedom.”