Accidents happen in the animal world, too.
Eloise, a 37-year-old siamang, surprised San Diego Zoo visitors, volunteers and staff last week when she went into labor and delivered a baby in her exhibit — despite the fact that the ape was on birth control and betrayed no visible sign that she was expecting, zoo workers said.
“It was amazing to see Eloise give birth,” Jill Andrews, animal care manager at the San Diego Zoo, said in a statement, “because she showed no outward signs of being pregnant.”
Delivered on Nov. 12, Eloise’s baby is the first infant siamang at the zoo in more than a decade. Eloise and her 35-year-old male companion Unkie already have six children together, which is why the zoo was using chemical contraception to keep them from having more: Having too many offspring would make them too dominant in the San Diego Zoo siamang population’s genetic pool.
Siamangs are small, endangered apes native to the tropical forests of Indonesia and Malaysia, according to the zoo. Siamangs don’t make nests (unlike other ape species) because they sleep upright, wedged in the fork of a tree. They are also among the few primates who pair up with their romantic partners long-term.
The zoo’s siamang population is a part of a breeding program called the Species Survival Program, which aims to restore endangered species’ populations while also guaranteeing genetic diversity.
“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,” Andrews said. “Still, we are overjoyed—because any birth of an endangered species is a reason to celebrate.”
The zoo said the baby’s gender will be revealed once animal care staff are able to give it a full exam, which should happen in the coming months.
“We’re just going to allow her to be a mama for right now,” zoo spokesman Andrew James said, according to the San Diego Union-Tribune.
Mother, baby and father are all doing well.
Logging and the spread of agriculture have cut into the apes’ habitat, pushing them to become endangered, according to the zoo. Another reason their population numbers have suffered is that poachers kill adult siamangs to sell their primate children as pets.
At 37, Eloise isn’t just old to be a new siamang mother — she’s old for her species: Siamangs’ life span in the wild is 25 to 30 years, according to the zoo.