Mexican wolf pups are kept in dens in Arizona, New Mexico

Federal wildlife managers released 11 critically endangered Mexican wolf pups into the wild, injecting a much-needed genetic boost to an otherwise limited genetic pool.

This effort is part of the US Fish and Wildlife Service Mutual Adoption Program It mixes puppies born in captivity and the wild as mother wolves give birth in the spring.

While the adoption process involves many agencies and detailed planning, the concept is straightforward. Captive-bred wolves are removed from their dens at birth and placed in alternative wild families.

But working on the ground can be tricky. Wildlife managers must remove the pups from their biological families, nurse them during transport, collect blood samples for further research and then place them in wild dens, sometimes with adult wolves inside.

It is done to help the population thrive. Genetic diversity is an important measure of the success of the Mexican wolf recovery program. With only seven founding individuals present, the species has a critically low gene pool. According to some genetic research, every Mexican wild wolf is nearly as closely related as siblings.