A pair of Mexican wolves that had been waiting for their final release into the wild in Arizona are heading back to captivity after federal officials determined that the alpha male of an existing pack behaved aggressively toward them.
Authorities with the U.S. Fish and Wildlife Service had pre-positioned the male and female in a temporary pen since they were removed in April from the Sevilleta National Wildlife Refuge in New Mexico. The wolves had been in a fenced area to allow them to acclimate to the release area in the Apache-Sitgreaves National Forest, in what authorities believed to be unoccupied wolf habitat.
The pair and their newborn pups were waiting to be released but wildlife officials noticed another wolf pair acting aggressively toward the penned wolves, indicating that they would defend their territory against the interlopers.
It was the second setback for the program in recent weeks. A male wolf was recaptured after he left his mate and their pups after being released last month.
There are only about 75 Mexican wolves in the wild, and the Fish and Wildlife Service said last week that it intends to place the animal on the Endangered Species List.