SYRACUSE, N.Y. (AP) — Two baby sambar monkeys were born several weeks apart at the Rosamond Gifford Zoo in upstate New York and are now being raised by keepers after their mothers showed a lack of maternal instinct, a zoo official said Thursday.

Iniko gave birth to Sisu on April 26, and Iniko’s older sister Kasi also gave birth to a female, Mushu, on May 11. The father of the big-eyed, big-eared babies was the leader of the Patas group, Mac, making them half-sisters.

The Rosamond Gifford squirrel monkey group lives in the zoo like the very social species in the wild, in a group consisting of one male and several females, according to the zoo. The survival rate of squirrel monkeys in the wild is relatively low because young monkey mothers are often unable or unwilling to raise their young.

Zookeepers watched for signs that Iniko and Kasi needed help and intervened when it became apparent that this was the case. Staff are raising the half-sisters together, drawing on experience raising Iniko after her mother died in childbirth in 2020.

“Given the difficulties this species faces in reproducing, Iniko and Kasi’s babies are an extraordinary contribution to the zoo’s herd of quisser monkeys and the North American population,” zoo director Ted Fox said in a press release.

The Associated Press