New Attention Towards Recent Rhino Extinctions: Western Black Rhino

dreamstime_xxl_18899530The emerging debate around the recent announcement of the Dallas Safari Club’s plans to auction a trophy hunt for a critically endangered black rhino in Namibia has touched off a firestorm of comments from concerned individuals and organizations around the world.  The International Rhino Foundation’s (IRF) commentary on this auction can be found on our home page, www.rhinos.org.  The debate touches upon the broad spectrum of hunting activities, which range from the culling of selected animals to the unregulated, illegal slaughter we know as poaching, which threatens the very existence of a number of critically endangered species. It also seems to have refocused attention towards recent rhino extinctions.

Species vs. Subspecies

Fortunately, we have not lost any rhino species in recent times, but at least two rhino subspecies have been lost in the past decade.  The difference between a species and a subspecies tends to cause a lot of confusion when extinctions are reported by the media. A species is one of the basic units of biological classification – a group of organisms capable of interbreeding and producing fertile offspring.  A species can be defined by many different measures, including similarity of DNA, morphology, or ecological niche.

Presence of specific locally-adapted traits may further subdivide species into “infraspecific taxa”, generally called subspecies.  A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more (including any that are extinct), never just one.  Think of it sort of as a “nested” system. Organisms that belong to different subspecies of the same species are capable of interbreeding and producing fertile offspring, but they often do not interbreed in nature because of geographic isolation or other factors. The differences between subspecies are usually less distinct than the differences between species. The characteristics attributed to subspecies usually have evolved as a result of geographic isolation.

So while it is a conservation tragedy to lose a subspecies, the loss of an entire species is incredibly more serious in evolutionary terms.

thelastremai
The Last Vietnamese Rhino

In Vietnam, the last Javan rhino from mainland Asia lost its life to poachers in April 2010. The victim was found in Cat Tien National Park, shot through the leg with its horn chopped off.  This female was the last known survivor of the subspecies Rhinoceros sondaicus lasiotis.  Ironically, this subspecies had already been written off more than 20 years earlier in 1988, just before the Cat Tien population was discovered.  The numbers were not in its favor, however, as only a handful of animals had managed to hang on, and it was only a matter of time and government neglect before the fate of this subspecies was sealed by a poacher’s bullet.

The Ill-Fated Western Black Rhino

Another rhino subspecies, Diceros bicornis longipes, the western black rhino, once roamed the woodlands and savannas of west-central Africa.  This subspecies was reported from several countries, and also has vanished.  Its demise came largely as the result of hunting for its horn and habitat loss.  Its decline probably was exacerbated by civil unrest and the capacity to purchase serious weapons with money from the sale of horn.  By the 1980s, western black rhinos were on the path to extinction, probably numbering only in the low hundreds. By 2000, less than a dozen were believed to survive.

The subspecies was last reported from Cameroon, but field surveys in 2006 could turn up no evidence of its existence. Biologists searched for any sign – footprints, dung or feeding marks on vegetation – but couldn’t find anything to indicate that any rhinos survived. Sadly, no new evidence has emerged since.  It’s not unheard of that a species or subspecies once believed to be extinct may then be “rediscovered”, but such cases are highly unlikely with creatures as large and conspicuous as rhinos. The “final” decision to declare a species extinct based on evidence of its absence rests with International Union for Conservation of Nature (IUCN), which maintains the global Red List of Threatened Species.

Black Rhino,  Diceros bicornis,  Pittsburgh Zoo

Black Rhino,
Diceros bicornis,
Pittsburgh Zoo

The black rhino subspecies that inhabits Namibia, Diceros bicornis bicornis, is in relatively good shape. Just under 2,000 remain, close to 90% in Namibia and the rest in South Africa, save for one lone animal that possibly may survive in Angola.  The southern black rhino, Diceros bicornis minor, is slightly more numerous and widespread, numbering nearly 2,300 individuals scattered over seven countries – South Africa, Zimbabwe, Tanzania, Zambia, Malawi, Swaziland, and Botswana. It is believed that no rhinos survive in Mozambique, essentially the “hub” for rhino poachers in southern Africa. The eastern black rhino, Diceros bicornis michaeli, is the least numerous of the remaining subspecies, with just under 800 animals left in Kenya, Tanzania and South Africa.

IRF’s Black Rhino Work

The IRF, working in close collaboration with Zimbabwe’s Lowveld Rhino Trust, helps to monitor and protect several hundred southern black rhinos (and white rhinos) in two privately-owned and operated wildlife conservancies that contain more than one-and-a-half million acres of suitable rhino habitat.  In fact, biologists believe that this region is capable of supporting a rhino population double that of its present size.  The IRF is also working closely with Wilderness Safaris in an attempt to reintroduce southern black rhinos to Botswana, as well as with zoological parks and breeding centers in North America and Australia to establish a sustainable captive population of this subspecies with clear linkages to field conservation.

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