Survey Finds 257 Mexican Gray Wolves Living in U.S. Southwest

The tepid 6% growth occurred mostly through reproduction in the wild; wolves who were released from captivity into the wild did not fare well. There were 87 pups-of-the-year seen alive at the end of 2023, including only one surviving pup out of 16 captive-born pups released into the dens of wild wolves last year.

All the Mexican gray wolves who have been reintroduced since 1998 came from just seven wild-caught wolves bred in captivity decades ago. Since that time the genetic diversity in today’s reintroduced population has dropped to just 2.09 of those seven, meaning every Mexican gray wolf is almost as closely related to the next as siblings are. This genetic diversity was lost due to live removals and killings, coupled with few effective releases.

Releases from captivity are necessary but insufficient to diversify the wild population because the captive population retains the genetic equivalent of 2.85 wolves, which is 36% more than in the wild population. In 2016 the Service began releasing captive-born pups. Since then 99 pups have been placed into wild wolves’ dens, but 73 of those 99 disappeared, while another 12 were found dead. Just 14 are known to be alive in the wild presently, including the one from last year.

Yet the Service still refuses to release wolf families from captivity together into the wild, a practice the agency itself has stated has a 66% success rate in areas with adequate prey. The last time the Service released a well-bonded male-female pair with pups was in 2006, after which it discontinued family releases because of livestock industry opposition.

Introducing Mexican gray wolves into southwestern Colorado to mate with northern gray wolves in the southern Rocky Mountains would further help foster genetic diversity.

Mexican wolf fertility and pup survival have been documented to decrease from inbreeding, but the Service’s artificial feeding of wild wolves increases their fertility and pup survival rates without solving the underlying inbreeding. In 2023 the Service systematically fed 16 wolf families, amounting to 29% of the 56 packs present at the end of the year.

Thirty-one wolves are known to have died in 2023. The Service has tentatively identified 11 as having been killed illegally and will likely eventually determine, based on past examples, that most of the rest also died from gunshots. The alpha male of the Mangas pack was shot in April by the U.S. Department of Agriculture for killing cattle. Another male wolf in New Mexico died inadvertently in an agency-set leghold trap in September. Two died after being hit by vehicles, and one died after suffering an injury from natural causes.