The Geographical Distribution of Roosevelt Sable in East Africa
by Dr Rolf Baldus
Wildlife conservation, support to protected areas and community-based management of natural resources has been a priority in Tanzanian-German development cooperation since 1987. Monitoring of wildlife populations and trends has been a part of these programs. In order to assess the conservation value of the Selous and Saadani Game Reserves and the surrounding buffer zones, the taxonomic status of the local sable population was regarded as important. The Wildlife Division and Deutsche Gesellschaft fuer Technische Zusammenarbeit (GTZ), the German bilateral development agency, therefore contracted the Berlin based “Institute for Zoo Biology and Wildlife Research” (IZW) to conduct a respective study. The scientists responsible for the study were Prof. R.R. Hofmannn, Prof. C. Pitra and Dr. D. Lieck- feldt.
Due to the generous support of Dr. R. Kock (Veterinary Unit of Kenya Wildlife Service) it was possible for the first time to collect tissue samples of nominate Hippotragus niger roosevelti for analysis in the Shimba Hills Nature Reserve in Kenya. For comparison, samples were also collected from the sable antelopes of the Selous and Saadani Game Reserves, Western and Southern Tanzania and Northern Mozambique.
The scientific results of the research were published amongst others by Baldus (1998), “The Eastern Tanzanian Sable Antelope is Roosevelt” (Gnusletter. IUCN Species Survival Commission. Vol.17, No. 2.), by Pitra, Hansen, Lieckfeldt & Arctander (2002) “An Exceptional Case of Historical Outbreeding in African Sable Antelope Populations” (Molecular Ecology, 11(7), 1197-1208) and by Pitra, Lieckfeldt & Baldus (2004) “Spatial Distribution of Roosevelt sable Antelope (Hippotragus niger roosevelti) in East Africa” (in preparation).
DNA analysis and comparison of the different samples col- lected proved that the sable antelopes living between the following border lines can all be regarded as belonging to the subspecies roosevelti:
Northern boundary: Shimba Hills National Park in South Eastern Kenya.
Western boundary: Western boundary of the Selous Game Reserve.
Eastern boundary: Indian Ocean
Southern boundary: Ruvuma river (Tanzania – Mozambique border)
Within these boundaries no evidence of hybridization with the Western and Southern sable types could be found. This means that roosevelti is an isolated and genetically clearly identifiable subspecies.
The subspecies has been exterminated in some parts of its former range, e.g. in South-Eastern Kenya except Shimba Hills (approx. 100 - 200 animals).
The analysis of further samples from Northern Mozambique will reveal whether these sable are indeed all of the Southern type, as our present knowledge indicates. Further analysis of samples from the western buffer zone of the Selous (including the Kilombero valley) might indicate that these sable are still roosevelti and the western distribution might not be limited by the Selous boundary, but more around 50 to 100 km west along the escarpment to the central highlands. It is also possible that the two subspecies have interbred there. But for any practical purpose this is rather insignificant.
Practical Consequences for Hunting Trophies
There is no hunting of sable neither in Kenya nor in Eastern Tanzania north of the Ruvu River. Therefore sable trophies originating from hunting blocks in the following areas can be regarded as roosevelti:
1. Selous Game Reserve
2. Northern buffer zone of Selous between Ruvu river and Selous
3. Eastern buffer zone of Selous between coast and Selous boundary
4. Southern buffer zone of Selous between Ruvuma river (Mo- zambique boundary) and Selous
We estimate the total number of sable in this area as between 7,000 and 12,000, at least half of which live outside the Selous Game Reserve. The subspecies is not endangered in Tanzania and can be hunted on a sustainable basis. It is protected by law with the exception of sable hunted by tourists in official hunting blocks and on the basis of a quota given by the Wildlife Division. There is no resident hunting for sable.
(Cartography by Mike Shand)