India chimpanzee birthday
Chimps usually live up to 40 years in the wild but longer in captivity Susana Vera/Reuters file photo

A zoo in the Indian capital of New Delhi is marking the rough birthday of the country's oldest living chimpanzee, Rita, although the exact date of her birth is still not known.

Rita, who was taken to the Delhi zoo in 1964 from Amsterdam at the age of four, will receive toys as presents on her 57th birthday. A cake will also be cut in her honour.

The authorities are marking the birthday in order to raise awareness of wildlife conservation.

"We will cut a cake and I'll feed a big slice to Rita with my hands," the zoo's director, Renu Singh, told the BBC.

"We will also screen some wildlife films for her as a birthday treat as she's very fond of watching videos and observes them very intently."

A giant television screen will also be placed outside her enclosure for the visitors to watch her.

Besides toys, Rita will also receive a new blanket as a birthday present. Though the chimp, described as a "very friendly ape", has no health problems, she does not leave her cage because of her old age.

Rita is the oldest living inmate in the zoo. Her birthday party comes just months after the zoo celebrated the 10th birthday of a white tiger.

"As its oldest inmate, she is a crucial part of the park," Raja Ram Singh, joint director of the National Zoological Park, told the Press Trust of India.

"She shows many human instincts. She wants to interact with her visitors, but old age forces her to stay back,"

Chimpanzees can live to about 40 in the wild but tend to live longer if kept in captivity.