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BUFFALO, N.Y. (CBSDFW.COM/AP) — One of the Buffalo Zoo’s gorillas has given birth after cooperating for ultrasounds during her pregnancy.

Zoo officials say the baby western lowland gorilla was born around 11 p.m. Sunday. As of Tuesday, no one had gotten close enough to see whether it’s a boy or girl.

Zoo keepers say they were able to monitor the 18-year-old mother Sydney’s pregnancy using ultrasound technology after training her to present her abdomen to keepers and remain calm during the process.

The gestation period of gorillas is eight and a half months. The zoo’s 28-year-old male gorilla, Koga, is the father.

Just last month, a western lowland gorilla was born at the Fort worth Zoo. First-time parents Gracie and Elmo welcomed a boy gorilla, on Saturday, December 5. Western lowland gorillas are listed as critically endangered by the International Union for Conservation of Nature.

The Fort Worth Zoo is the only zoo in the nation to house representatives of all four great ape species — gorillas, orangutans, chimpanzees and bonobos.

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