Officials at the Maryland Zoo in Baltimore are investigating the death of a middle-aged female chimpanzee that was found lifeless in an enclosure early Wednesday morning, several hours after being anesthetized for a scheduled physical exam.
Whether the anesthesia was a factor in the animal's death will be reviewed as part of a necropsy, or animal autopsy, zoo officials said.
The 21-year-old primate, named Renee, was among the first group of chimpanzees to inhabit the zoo's Chimpanzee Forest following its opening in 1995. She arrived in Baltimore with her mother, Joice, the troop's matriarch, from the Yerkes Primate Center in Atlanta.
Chimpanzees live an average of 40 to 45 years, and can live to 60 in captivity, according to the National Primate Research Center at the University of Wisconsin-Madison.
Joice is 41 years old and still living in the Chimpanzee Forest, said Jane Ballentine, a zoo spokeswoman.
Zoo officials said Renee was anesthetized in the Chimpanzee Forest on Tuesday, taken to a veterinary hospital on the zoo's grounds and given her bi-annual physical exam.
"During her exam, we found no serious health issues," Dr. Ellen Bronson, the zoo's senior veterinarian, said in a statement.
Renee was then transported back to an individual enclosure for observation.
"She was recovering slowly but well," Ballentine said. "They didn't have any cause for concern while staff was monitoring her."
The chimpanzee was not observed overnight and was found dead in the morning by zoo staff, Ballentine said. The zoo now has 10 chimpanzees.
Zoo officials mourned the loss.
"I worked with the chimps when they first arrived in 1995, and Renee was playful, mischievous and full of life," said Mike McClure, the zoo's general curator, in a statement. "Watching her grow up has been amazing. Joice was stout and lively when she first arrived at the Zoo, and Renee grew into the spitting image of her mother. I am very saddened by her loss."
"I would describe her as a 'chimp's chimp,' " said Carey Ricciardone, mammal collection and conservation manager, in a statement. "Renee didn't care much for human interaction but could be very playful with zookeepers when she wanted to, on her terms. She was very smart and watchful, and was a high-ranking female in the troop. I know she will be fondly remembered by zoo staff, volunteers, and guests."
Ballentine said it is difficult to attribute human emotions like grief to animals, even primates, but that zoo staff did show the other chimpanzees Renee's body before removing it from the enclosure.
The necropsy will be conducted by zoo veterinarians and veterinary pathologists from the Johns Hopkins University, the zoo said. Results could take several weeks.