ST. LOUIS – A male western lowland gorilla arrived at Saint Louis Zoo last week to join the zoo’s bachelor program, with the long-term goal of propagating the species.

Kayin was born at the Buffalo Zoo in 2016, and has lived in a family troop with his parents, aunts, and siblings ever since. Kayin, now 7, is at an age where males typically leave their troop to find a mate or join what’s known as a bachelor gorilla group.

The western lowland gorilla is the most common of four subspecies of gorilla. However, it’s a critically-endangered species, and they are facing complete extinction in the wild.

Kayin will be part of the zoo’s bachelor gorilla group, joining Joe, Bakari, and Zachary in the Jungle of the Apes exhibit. The males live together until they’re ready to become part of a breeding group.

These bachelor groups are commonly found in the wild, the zoo says.

At present, Kayin is being kept in parts of the zoo that are off-limits to guests. He’ll be introduced to the outdoor habitats this summer.

Kayin’s transfer came at the recommendation of the Association of Zoos and Aquariums’ Species Survival Plan, a program designed to strengthen western lowland gorilla populations in North American zoos.