ALBUQUERQUE, N.M. (AP) — It's a carefully planned mission that involves coordination across state lines — from Mexican gray wolf dens hidden deep in the woods of New Mexico and Arizona to breeding facilities at zoos and special conservation centers around the U.S.
It's also about timing as wolves in the wild and those in captivity need to be having pups at the same time to ensure a smooth transition.
Pups born within a couple days of each other are the best candidates for a fostering program that aims to get more pups out of captivity and into the wild in hopes of boosting the genetic diversity of the endangered species.
"It's really a balance of science and astrology — because the stars have to align," said Maggie Dwire, a biologist with the U.S. Fish and Wildlife Service team that oversees recovery of Mexican gray wolves in the American Southwest.
U.S. officials claimed success Tuesday, saying 12 pups were placed this year with packs living in a mountainous region along the New Mexico-Arizona state line.
That marks the most pups fostered in a single breeding season since biologists first attempted the technique in 2014 by moving wild-born pups from one wild pack to another.
In 2016, they tried placing captive-born pups with wild packs, discovering that the survival rate of the foster pups was on par with those born in the wild.
Since 2014, 30 pups have been fostered by wild packs, another handful has been transferred among wild packs and seven were taken from the wild and reared by captive parents.
Jim deVos, assistant director for wildlife management at the Arizona Game and Fish Department, called the fostering project one of the most important when it comes to recovering the species.
"Given the very small initial population of wolves, infusing new genetics into the growing wolf population is a crucial step to recovery," he said.
More Mexican wolves are in the wild now than at any time since they were nearly exterminated decades ago. Mexican wolves, a subspecies of the Western gray wolf, have faced a difficult road to recovery that has been complicated by politics, legal fights and conflicts involving livestock.
At least 131 of the predators now span southwestern New Mexico and southeastern Arizona.
Members of a field team track the wild wolves via radio collars. When females stop roaming, that usually means they're ready to den. The team will keep watch, knowing that pups will likely be born in about two months.
Officials at the captive breeding facilities also monitor their pairs for denning behavior.
"That's the astrology part," Dwire said. "Whichever facility aligns is the one we're going to pull from."
Then begins the stressful part: Transporting tiny pups — their eyes still closed — in soft-sided containers. The pups still require tube feeding and warm temperatures that mimic the dark, cozy confines of a den where they would snuggle with their litter mates.
This year's foster class came from the Endangered Wolf Center in Missouri, the Wolf Conservation Center in New York and Sedgwick County Zoo in Kansas.
In the wild, the team pulls the wild pups from their den. Cheek swabs collect DNA and health checks are done. Then they're mixed with the foster pups, rubbing them together and using dirt and fur from the den to ensure they all smell the same as they're slipped back into the den before mom returns.
There's no fooling the female wolf, but Dwire said the animal either immediately goes into the den and starts caring for the litter or moves them and then starts tending to them.
"That maternal instinct kicks in," she said.