Black rhino birth a true labour of love

NSW zookeepers are brimming with pride after several years of patient work ended with the safe arrival of a perky little black rhino.

The chunky, big-headed boy emerged feet first at Taronga Western Plains Zoo in Dubbo two weeks ago.

The calf, which is yet to be named, is the 16th born under the zoo's long-running breeding program for the critically endangered species.

And he gets the award for the "most hard won calf" given it took an entire team of people years and hundreds of carefully orchestrated ultrasounds to achieve his conception.

His mother, 13-year-old Kufara, had her first calf, Mesi, six years ago but failed to conceive naturally again.

When zoo experts delved into why, they discovered the outward signs she displayed of being in season didn't line up with the release of her eggs, so the sexy time she was spending with the bulls was futile.

Black rhino supervisor Jennifer Conaghan explains what it took to solve the problem.

"We ended up having to internally ultrasound her twice a week ... to determine the size of her follicle to pinpoint when she was most receptive, regardless of what behaviour she as displaying."

But given black rhinos are notoriously sensitive that meant a whole lot of work to create precisely the right conditions for her to willingly submit to the process.

"Of all the rhino species, black rhinos are the most high maintenance. They are very sensitive and complex," Miss Conaghan says.

"It only takes them to have a perceived negative experience - it might be 'Oh a bird landed on the fence and it scared me. I'm done'. And it's not I'm done for a week. It's I'm done."

Which explains why every single one of those hundreds of ultrasounds was a four-person job.

Kufara had to come willingly. 

She had to be able to walk away if she didn't like any aspect of the intimate procedure involving a vet's arm and the rectum.

And she had to have some nice distractions from a dedicated pat provider and a snack attendant, while two others at the back got the job done.

The elaborate process has also uncovered new knowledge about the species, says Justine O'Brien, Taronga's manager of conservation science.

Kufara gave birth 490 days after mating, exceeding the longest recorded gestation length of 486 days.

"It shows that normal range can vary, with more and more animals that we are monitoring. That's a classic thing for threatened species, where there are not many left, and we don't get the opportunity to gather this data," Dr O'Brien says.

"So every rhino in our zoos, and those that we're monitoring in wild populations, are so valuable for giving us this information."

There are fewer than 6,500 black rhinos left in the wild due to habitat destruction, and poaching for the illegal rhino horn trade.