Babu, the only remaining chimpanzee at the zoo, in his enclosure on Tuesday. Picture by Tamaghna Banerjee

A 27-year-old female chimpanzee who had been in respiratory distress for a week died in her cage at the zoo on Tuesday morning, raising questions about the upkeep of animals in the Alipore facility. Chimpanzees live up to 60 years in captivity.

The zoo authorities said Rani, who had been brought to the city from the Cologne zoo in Germany in 1989, was suffering from age-related ailments. “Her lungs were not functioning properly and she was having acute difficulty breathing since last Thursday. She was being treated in her cage,” said Subir Chowdhury, the director of Alipore Zoological Garden.

A keeper found her dead in her cage at 6.40am.

Chowdhury claimed the average life span of chimpanzees is around 30 years, although the board hanging outside the chimpanzee enclosure says they live for 37 years on an average. According to wildlife experts, chimpanzees live 40-45 years in the wild and longer in captivity because of ready access to food and medical care.

“If the chimpanzee’s condition was critical why didn’t the authorities shift her to a hospital? Several animals have been falling ill at the zoo. We have written to the forest minister demanding a thorough probe into the chimpanzee’s untimely death,” said Rakesh Singh, the leader of an employees’ federation affiliated to the Congress.

Chowdhury told Metro that they would have had to tranquillise the chimpanzee to shift her from the cage to the adjacent hospital but that would have worsened her condition.

A wildlife expert said the chimpanzee could have been shifted without tranquillising her. “The chimpanzee could have been put in a smaller cage or taken to the hospital for better diagnosis,” said Pradeep Vyas, the director of Sunderbans Biosphere Reserve.

State forest minister Hiten Burman, who is in north Bengal, said he would go through the chimpanzee’s post-mortem report and other documents to decide whether to order an inquiry.

In April 2010, a female chimpanzee named Jessy had fallen to her death while swinging from one tree to another in the zoo. A probe revealed the chimp had been sedated before it escaped and started climbing a tree.