Biologists with the Mexican Wolf Interagency Field Team learned that a fostered wolf pup introduced to a pack two years ago has produced a pup.

I’s being called a “critical breakthrough” in Mexican wolf management, by the Arizona Game and Fish Department.

Genetic testing by the U.S. Fish and Wildlife Service of a male wolf revealed it was the offspring of a female that was fostered into a den in New Mexico in 2014.

According to a statement from Game and Fish, the agency supports this fostering technique that introduces very young pups in captivity and places them into a wild born litter of the same age.