The Western black rhinoceros is extinct. There have been no reports or sightings of the species, Diceros bicornis longpipes, since 2006, reports the International Union for Conservation of Nature and Natural Resources (ICUN). Once widespread throughout central Africa, the number of Western black rhinoceroses continued to drop until they disappeared, primarily due to poaching. There aren't any known to be held in captivity.

But that sad note is just part of the bigger story. All black rhinos are in trouble, and a new conservation plan must be developed to save the broader group from extinction, say researchers from Cardiff University.

In their study, the Cardiff researchers compared the genes of living and extinct rhinos by extracting DNA from tissue and fecal samples from wild animals and from the skin of museum specimens. They measured genetic diversity in the species from the past versus the present and compared the profiles of animals in various regions of Africa. What they found was a major drop in genetic diversity. They discovered that 44 of 64 genetic lineages no longer exist, which suggests that "the future is bleak" unless a new conservation plan is put in place.

"Our findings reveal that hunting and habitat loss has reduced the evolutionary potential of the black rhinoceros dramatically over the last 200 years. The magnitude of this loss in genetic diversity really did surprise us — we did not expect it to be so profound," Professor Mike Bruford from Cardiff University’s School of Biosciences, said in a statement.

“The decline in the species’ genetic diversity threatens to compromise its potential to adapt in the future as the climate and African landscape changes due to increased pressure from man ..."

To save the animals from extinction, it's key to conserve genetically distinct populations, the researchers say.

"The new genetic data we have collected will allow us to identify populations of priority for conservation, giving us a better chance of preventing the species from total extinction," Bruford says.

History of the black rhinoceros

A black rhinoceros mother and calf visit a watering hole in the Etosha National Park in Namibia. A black rhinoceros mother and calf visit a watering hole in the Etosha National Park in Namibia. (Photo: Yathin S Krishnappa/Wikimedia Commons)

The World Wildlife Fund recalls a blunt 1961 Daily Mirror headline: “DOOMED.” It accompanied a full-page photo of two African rhinos and an article that said the rhinos were “doomed to disappear from the face of the earth due to man’s folly, greed, neglect.”

There were about 100,000 black rhinos in 1960, according to the IUCN. Between 1970 and 1992, 96 percent of Africa's remaining black rhinos were killed in a long-lasting wave of poaching, reports the WWF. Their numbers bottomed out to just 2,410 in 1995. Today, the black rhino is listed as critically endangered.

More recently, conservation efforts have offered glimmers of hope, as those numbers grew to 4,880 in 2010. Two black rhino babies were born in Tanzania in October 2016 to mothers that had been raised in captivity and then released into the wild, reports the BBC.

Four range states — South Africa, Namibia, Zimbabwe and Kenya — currently conserve the majority (96.1 percent) of remaining black rhinos in the wild.

A rising demand for rhino horn, which is used in some cultures for folk remedies, has triggered a recent increase in poaching in South Africa, reports the WWF. In 2014, 1,215 rhinos were poached in South Africa, a 21 percent increase from the year before.

The researchers address this in their study, published in the journal Scientific Reports:

In light of the present crisis, conservation priorities should remain the protection and survival of extant populations. It is clear that for the black rhinoceros to have a future in which evolutionary processes can occur, management against the ongoing poaching threat is the top priority. However once the current poaching episode subsides, the genetic management of the remaining, reduced stocks will undoubtedly be a key focus for the long-term survival of the species.

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.