Born on Friday night, the calf is the fifth black rhino to be born under the zoo's breeding program and is the first female for Western Plains Zoo.

The birth of a female means the as-yet-unnamed calf can stay at the zoo to take part in an internationally-renowned program to breed with unrelated males already in residence at the zoo.

According to Western Plains life sciences manager for Africa Andrew Thorne, staff could not be happier.

"This is just huge," he said.

"With the birth of four boys before, we've found we already had enough male rhinos and for the breeding program we need more females than males.

"We certainly won't be shipping this one off - there are males here that are not related to her so we can breed her with them."

The calf was born after a 458-day pregnancy, with the baby walking around the enclosure within an hour and suckling from mother Kalungwizi within two hours.

The newborn, sired by Siabuwa, brings the number of black rhinos at Western Plains Zoo to 12.

On show to the local media yesterday, the calf was happy to stick by mum, who charged forcefully at the fence if she thought inquisitive photographers or journalists were getting too close.

Mr Thorne said every birth of a black rhino was important.

"There are only 250 in captivity around the world and only 2800 left in the wild, so one birth, every birth, is significant," he said.

"Western Plains has five per cent of the world's captive population of black rhinos and our success rate is one of the best in the world.

"It's a real coup for us."

Unlike other endangered animals, habitat destruction is not the main reason for the declining numbers of rhinos in the wild - hunting and poaching is the number one cause.

Rhinos continue to be killed for the horn, which is used in Asiatic medicines and for dagger handles.

In 1970 there were more than 65,000 black rhinoceros in Africa but by 1980 this number had plummeted to 15,000 and to only 3000 in 1990.

The zoo's acting general manager Steve Rees said the birth was "outstanding news".

"The survival of the species depends on the success of these zoo-based breeding programs which are establishing a gene pool outside Africa," he said.

"Western Plains Zoo staff have been dedicated to this breeding program and have worked hard to make this birth a success."

Mother and calf will now be left alone for bonding and to ensure the calf's health before both go back on display for the public.