We conducted an extensive survey in search of hybrid baboons between
Papio hamadryas and
P. anubis along the Wabi-Shebeli river at the border of the Arusi and Bale Regions, Ethiopia. We made inquiries of villagers on the
roadsides concerning the existence of baboon species. We also conducted direct observations at several sites. There are three
routes which lead to the north bank of the Wabi-Shebeli river (Arusi Region), and we found hybrid baboons on the bank of the
Wabi-Shebeli river in two routes among the three. We found hamadryas baboons in all of the three routes at the cliff areas.
There are two routes which lead to the south bank of the Wabi-Shebeli river (Bale Region). We conducted a survey on one of
the two. We found hamadryas baboons at the cliff areas of the route.
We observed a population of gelada baboons along the cliff extending over 20 km along the north bank of the Wabi-Shebeli river
(Arusi Region). This area is far to the south of the known distribution range of gelada baboons (Yalden et al., 1977). The gelada baboons of this area appeared to represent a different form (subspecies?) from those at Debre Sina
(Showa Region) based on our observations in both areas.
We reached the conclusion that the distributions of baboon species along the Wabi-Shebeli river may have been strongly affected
by the intensive cultivation on the plateau of the highland. The distribution patterns of the three baboon species,P. anubis, P. hamadryas, andTheropithecus gelada, appeared to be influenced by their individual adaptabilities to the cliff environment. Hamadryas baboons were distributed
continuously along the cliff and the narrow lowland of the Wabi-Shebeli river. Anubis baboons were distributed discontinuously
on the cliffs, and their populations tended to be small and isolated. These anubis baboons were strongly hybridized with hamadryas
baboons.
Key Words Hybrid baboons -
Papio hamadryas
-
Theropithecus gelada