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I decided to join ranger Andrew Stainthorpe on a walk through the Hlangwini breeding and quarantine boma, situated just south of the camp. Although such a walk doesn't offer the same experience as the popular wilderness trails conducted by qualified guides, it does offer visitors to Pretoriuskop the experience of walking through the African bush, albeit in the safe sanctuary of a predator-proof holding camp.

According to Andrew, the 300-hectare enclosure hosts Lichtenstein's hartebeest, tsessebe, steenbok, kudu, mountain reedbuck and, much to my surprise, a 'roable'. The latter is a bizarre creature resulting from the natural hybridisation between a roan and a sable and the one at Hlangwini is the only known example.

On our three-hour ramble we had distant sightings of Lichtenstein's hartebeest, tsessebe and kudu and spent much of the walk identifying trees. The highlight was a brief sighting of the roable: I clearly noticed a flash of a roan's characteristic masked face curiously blended with a sable's elegantly curved horns.

Then most probably a crossing between Roan and Sable. I have read somewhere that this does occur and that is one of the reasons why both are on the danger list.

In closely related animals such as black and blue wildebeest or blesbok and bontebok, hybridisation is a big problem. This is also the reason why you are not supposed to keep the two species together nor move the one species in to the distribution area of the other.

I do however not think that it is a real problem between roan and sable, nor a substantial reason for them being scarce. That has more to do with factors such as habitat preference and the influence of man.

So are the males off these offspring fertile? While Roan and Sable are similar they are not as closely related to one another as Bontebock are to Blesbuck. Just wondering if maybe they throw a "mule" effect?

Due to varaitions, one can always find fertile hyrbrids. In some cases (with very closely related "species") it is quite common, while in others, such as the mule, it ought to be very rare.

Don't know how the case is with the roan/sable. Any litterature or other references anyone?

Absence of geographic chromosomal variation in the roan and sable antelope and the cytogenetics of a naturally occurring hybrid.

Robinson TJ, Harley EH.

Department of Zoology and Entomology, University of Pretoria, South Africa.

The determination of geographic chromosomal variation in rare or endangered species, or those of special management concern, is important, since geographically defined cytotypes can negatively influence breeding programs involving founders drawn from widely divergent localities. We cytogenetically analyzed specimens of the roan (Hippotragus equinus) and sable antelope (H. niger) collected from widely divergent localities throughout their respective ranges. Each species was characterized by a diploid number of 60 and an invariant karyotype. In contrast to the absence of intraspecific variation, however, the two species differ with respect to centromeric constitutive heterochromatin and numbers of nucleolar organizer regions. These cytogenetic landmarks were subsequently used to verify an anecdotal account of a naturally occurring roan x sable hybrid. The data show that, despite their markedly distinct phenotypes, the roan and sable antelope are nonetheless sufficiently similar genetically to produce viable offspring. Hybridization, although a rare event between these species, is probably partly promoted by behavioral differences which are not always sufficient to prevent mating between them.

Fertile hybrids seem to be more common among bird species than mammals?? (and no!, I'm not bringing up the Mallard subject again! )

...and the one at Hlangwini is the only known example...

<...>By looking at the study Jose added, it would seem that other "naturally occuring roables" could have been recorded- interesting!<...>

The story of a roble (Africa Geographic, March 2006 issue, page 14).

Dr. Richard Estes found one known hybrid of the two Hippotragus species. In the Kruger NP.

Some quotes from the article (comments made by Dr. Ian Whyte, Sanparks research's manager for large herbivores ):

"This hybrid resulted from a situation where a roan bull joined a sable herd in the area north of Satara in Kruger. ...This roble - as this possible unique roan x sable had been dubbed - was placed in a large enclosure located in the Pretoriuskop area of the park, a section free of other sable or roan. Last year it was suggested that as the hybrid was now 19 years old, it should be euthanased for the benefit of science."

"Before this could happen, however, it died of natural causes and so ended the life of the roble."

Thanks Impisi08!
So it happened in the park and not in the enclosure- that's interesting!