The chimpanzee enclosure at Alipore zoo, where Cuzo and Jesse were kept. (Anindya Shankar Ray)

Calcutta, June 26: A 24-year-old male chimpanzee, which lost its partner three months ago, died at Alipore zoo on Friday morning.

Zoo authorities said Cuzo was suffering from old age-related ailments. “His kidneys, lungs and heart were not functioning properly. There were several dark spots on his heart and kidneys,” said Raju Das, the director of Alipore Zoological Garden.

Das said the average life expectancy of a chimpanzee was between 18 and 26 years, though a board hanging in front of Cuzo and his partner Jessi’s enclosure said chimpanzees live for 37 years on an average.

A wildlife expert said Cuzo could have also died of zoochosis, a sickness that many animals develop in captivity.

“Understanding the psychology of an animal is very important,” said Samik Gupta, a South Asia member of the International Union for the Conservation of Nature. “It is very common among chimpanzees to suffer from zoochosis.”

Abnormal behaviour resulting from zoochosis include repeated pacing, rocking, vomiting and even self-mutilation.

However, zoo authorities said they had not observed symptoms of zoochosis in Cuzo. “We did not notice any signs of zoochosis in Cuzo. Veterinary experts had been treating him for a long time,” Das said.

Zoo authorities said Cuzo had stopped eating a week back. “We were treating him but could not save him,” Das said.

Cuzo’s partner Jessi died three months ago. Both had been living in the zoo for the past 13 years.

On Saturday, an empty chimpanzee enclosure greeted visitors. Alipore zoo now has two chimpanzees left.