Zoo Atlanta received a Halloween night surprise when Kuchi, a 21-year-old gorilla, delivered twins at Zoo Atlanta, either late Monday or early Tuesday.
It was only the seventh time since 1956, when gorilla births were first monitored, that a twin birth has been recorded in North America, said Dr. Tara Stoinski, a Zoo Atlanta researcher who studies the endangered species.
It is the first twin gorilla birth in North America since 1999.
"What we're seeing [is] one set of twins for every 160 births," said Dan Wharton, the director of the Central Park Zoo in New York. Wharton is coordinator of the gorilla species survival plan, a management system that aids captive populations that is administered by the American Zoo and Aquarium Association. "That's roughly twice as rare as [twin] human births."