"The female black bears have been separated from the male as we only have two enclosures, which are enough for six bears. If they breed again, there will be a space crunch. We have separated the males and the females from the enclosure and placed them a few metres away," said a senior zoo official, who did not want to be identified.

The zoo has six Himalayan black bears - two males, three females and a bear cub, born this March. "The other reason for separating them is that usually the male bears get ferocious at mating time and pick up fights with the females, causing injuries to the newborn. We have separated them in order to avoid this too," the zoo official said even as the eight-month-old cub, cuddled up with its mother, snored loudly.

Apart from the bears, the zoo officials are planning to separate deer which are prolific breeders during winter, except certain endangered species like sangai, chinkara and chowchinga.

"If we allow unhindered mating, then the Delhi Zoo would have little space left for deer as they are already over-populated," the official told IANS. The zoo houses about 11 species and sub-species of antelopes and deer, of which three varieties -- blackbucks, the sambar and hog deer -- are over-populated.

"We have over 100 blackbucks, 70 sambar deer and 50 hog deer. Winters are the favourite season for deer to mate. The blackbuck antelope is an endangered species and we cannot carry out a birth control procedure. So to stop them from mating, we have to keep the males and females separate," the official added.

Spread over an area of 240 acres, the Delhi Zoo houses over 1,000 varieties of mammals, reptiles and avian species. It is also home to many endangered species in India. The leopard cat, Indian rhinoceros, hippopotamus, blackbuck, Indian gazelle and lion-tailed macaque are some of the animals found here.