A 1-year-old wolf pup is examined for general health during the annual Mexican gray wolf count on Feb. 1, 2020, in the Apache National Forest near Alpine. A consortium of federal and state agencies responsible for managing wild populations of the endangered canine visually counts packs and pack members and evaluates wolves for general health.

ALPINE — On a clear, frosty February day in eastern Arizona, ice hugs sidewalks and piles up in the shade of pine trees, steep slopes and buildings. Snowdrifts from a recent storm paint the nearby slopes glittering white in the bright sunlight, the promise of a warmer day ahead.

But while the temperature is just 36 degrees, the timing is right for the annual count of the endangered Mexican gray wolf across east-central Arizona and western New Mexico. The process usually stretches from November to the beginning of February.

For the past three months, biologists and technicians have roamed the region enumerating wolves and their packs in the Apache-Sitgreaves and Gila national forests. They’re members of the Interagency Field Team, a consortium of federal, tribal and state agencies charged with ensuring the recovery of one of the country’s most imperiled wolf species.

On this day, a group of nearly 20 biologists, technicians, managers and volunteers were gathering for the next step in the count, to survey at least one member of each Mexican gray wolf pack in Arizona and New Mexico and collar wolves that were previously not collared.

The annual count is critical in the ongoing effort to rebuild the population of wolves on a landscape where the predator was once all but eradicated.

The government tracks the progress of the wolves’ recovery using the wild population, which has increased an average of 12% since 2009. The U.S. Fish and Wildlife Service’s 2017 recovery plan says that one goal for taking the wolf off the endangered species list is demonstrating an average of 320 wolves over an 8-year period. The 2018 count showed that the wild wolf population grew to 131 from 117, with 64 of them roaming Arizona.

Locating and collaring previously uncontacted wolves supports another key goal of the recovery plan: widening the packs’ genetic pool. Each “new” wolf has a DNA sample taken. The results become part of the “studbook,” a listing of every known wolf, living and dead, in the recovery program.

Because the entire population of wolves, both in the wild and in captivity, is descended from just seven canids, increasing genetic diversity is vital to their long-term viability.

Read more: Health of packs studied, new wolves identified in annual Mexican gray wolf count