A 49-year-old chimpanzee at the Toledo Zoo has died.
Fifi, who came to the zoo in 1963 at the age of three, died Friday, a day after her keepers noticed she seemed stiff and tired, zoo officials announced on Sunday.
She was one of the oldest females in the North American zoo population.
A necropsy performed Friday revealed possible blood vessel abnormalities in the brain and further tests are pending.
Fifi's keepers noticed on Thursday that the chimpanzee seemed stiff and tired and she was started on medication after a visual examination.
By Friday morning her condition was improving and she was more active, but later that afternoon she became disoriented. She deteriorated rapidly and died.
Fifi was easily identified in the zoo's Kingdom of the Apes exhibit by the small white toy alligator she carried with her for more than nine years.
Fifi's death leaves the zoo with one chimpanzee, the 50-year-old male named Harvey.
The Toledo Zoo plans to work with the chimpanzee Species Survival Plan, which is a cooperative breeding and conservation plan created by the Association of Zoos and Aquariums, to decide the best social situation for Harvey.