A 37-year-old Siamang caught employees at the San Diego Zoo by surprise when she gave birth to a healthy baby on Nov. 12.
“Baby alert Eloise the siamang welcomed a wee surprise last week,” the San Diego Zoo announced on Twitter Sunday.
Not only were zookeepers shocked by Eloise’s surprise pregnancy, but they thought it was nearly impossible, considering the Siamang — a type of ape in the family of Gibbon native to Indonesia and Thailand, had been on birth control for the past several years.
According to the San Diego Zoo, Siamangs are on the endangered list.
According to the San Diego Union-Tribune, Eloise and her partner Unkie, 35, are already parents to six other Gibbons.
After Eloise and Unkie, who have been together for many years, welcomed their sixth child in 2006 at the zoo, Eloise was placed on a chemical contraception in an attempt to maintain genetic diversity in the zoo population of the Siamang species, USA Today reported.
“We’re not certain why birth control didn’t work in this case, but as with humans, it is not uncommon for contraceptive failure to happen from time to time,” Jill Andrews, animal care manager at the San Diego Zoo said in a statement obtained by USA Today and The Union-Tribune.
“It was amazing… she showed no outward signs of being pregnant.”
“Still, we are overjoyed— because any birth of an endangered species is a reason to celebrate,” Andrews added.
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At this time, the sex of the baby Siamang is unknown as zookeepers haven’t been able to come in contact with the baby. The Union-Tribune reports that Siamang mothers are fiercely protective of their young.
“We’re just going to allow her to be a mama for right now,” zoo spokesman Andrew James told The Union-Tribune.
Once zookeepers determine the sex of the baby they will come up with a name.