The death of a 22-year-old female chimpanzee at Alipore zoo on Thursday has turned the spotlight on the living conditions of the inmates of India’s oldest zoo.

The chimpanzee, Jessy, was probably under sedation when she fell while swinging from a branch of a 30ft tall tree and died of injuries to her lung and liver.

Climbing trees and swinging come naturally to primates but at Alipore zoo the chimps are not exposed to trees.

“I have found out that Jessy had never climbed trees earlier,” said zoo director Raju Das.

Another senior official of the zoo said: “The chimps swing on the parallel bars outside their cells. We have never seen them swing on trees.”

According to a wildlife expert, the zoo authorities had not created the right environment for primates. “They should plant trees in the enclosure,” he said.

Alipore zoo had four chimpanzees, including Jessy, who lived in pairs in cells in the primate enclosure. The enclosure has only two trees in its rear portion, but the chimps are not allowed to go near them, admitted zoo officials.

A probe also revealed lapses by the zoo authorities and doctors attending to Jessy.

“She was beaten up and bitten by her partner eight days ago but she was not shifted to a separate cell. Only when her wound got worse on Thursday did two veterinary doctors and her keeper decide to shift her,” a zoo official said.

They tranquillised her around 1pm on Thursday. But within 10 minutes she woke up and climbed a nearby tree, another zoo official said. “The effect of the sedative had probably not worn off,” he added.

Jessy and her partner Teju were brought to the zoo in 1997 from the UK.