A female sloth bear on loan to the Toledo Zoo for breeding has been found dead in its den, where it had been isolated to give birth.
Initial necropsy results showed no obvious cause of death, but the initial results showed that Medusa, 18, was not pregnant, Doug Porter, zoo assistant director, said.
The zoo will investigate whether the female's isolation, because it was not pregnant, was a factor in the death, Mr. Porter said.
“It may be when bears are pregnant, their physiology changes,” allowing isolation, Mr. Porter said. “Obviously, if she's not pregnant, her physiology is not going to change.”
Medusa was denned Nov. 17.
She was loaded with chow, separated from all other zoo life, and visited by keepers only once a week.
The reason? Because zoo staff members saw her breeding with Hans, 6, and expected a birth by early January.
“We don't have the fancy techniques humans do to determine pregnancy” in bears, Mr. Porter said. “When we do see confirmed breeding, we hope for the best.
“The female [bear] in the wild will isolate herself, den up, and have her cubs,” he said. “That's what we try to simulate in the zoo - get the male away so he's not banging on the door. We don't clean. We don't feed. The idea is that the female will begin to feel secure, and she'll have cubs.”
A keeper found Medusa's body Monday during a weekly visit. The bear likely was dead “only a matter of a few days,” Mr. Porter said.
“We're still asking our selves what might we do different, are there better techniques to determine pregnancy,” he said.
Sloth bears typically live into their 20s in the wild and in their 30s in captivity, Andi Norman, zoo spokeswoman, said.
Medusa arrived last year from the Detroit Zoo, where she had given birth in 1996 to a male cub and a female cub, Ms. Norman said.
Medusa's partner sloth bear, Hans, arrived in 1997 from the Warsaw Zoo with a female sibling, which has since gone to the National Zoo in Washington.
The sloth bear, native to the Indian subcontinent and Sri Lanka, is protected by international treaty and is rare in zoos, Mr. Porter said. The Toledo Zoo had hoped to contribute to the population by breeding Medusa and plans to continue efforts with Hans.
The male bear “is valuable for the gene pool,” Mr. Porter said. “We're going to scramble around to find another female to pair up with him.”
The zoo's last American black bear was euthanized in August, 1998, after veterinarians found a cancerous mass in its abdomen.
Its African leopard, 23, was euthanized in August, 2000, after a seizure and liver disease. The zoo's last cheetah, 18, was euthanized in May because it had gone blind, and a female chimpanzee, 42, died in March from heart failure and pneumonia.