Biogeography, Taxonomy, Abundance, and Conservation Status of the Primates of Northeast Uganda and West Kenya
Report for the National Geographic Society
Thomas M. Butynski & Yvonne A. de Jong
Eastern Africa Primate Diversity and Conservation Program & Lolldaiga Hills Research Programme
At the country-level, the biogeography, taxonomy, abundance, and conservation status of most of East Africa’s non-human primates remains poorly-known. During this survey, ‘rapid surveys’ were used to gather data on the biogeography, taxonomy, abundance, and conservation status of the primates of northeast Uganda.
A total of 402 h of survey were conducted (261 h diurnal and 141 h nocturnal, including 125 h listening) during two field trips in west Kenya and northeast Uganda. The two principal researchers each spent 30 days in the field. A total of 5,787 km were surveyed (5,690 km diurnal, 97 km nocturnal).
Natural history and conservation data were obtained for seven genera, eight species, and 11 subspecies of primate. In addition, indirect evidence for eastern robust chimpanzee Pan troglodytes schweinfurthii was collected in the Otzi Mts., north Uganda.
Diurnal primates were encountered at 0.01 groups/km and 0.27 groups/h (n=62 groups) during vehicle surveys and 0.21 groups/km and 0.42 groups/h (n=12) during foot surveys. These groups represented five genera, six species, and nine subspecies; western guereza Colobus guereza occidentalis (n=2 groups), Mau Forest guereza Colobus guereza matschiei (n=17), Mt. Kenya guereza Colobus guereza kikuyuensis (n=3), Dodinga Hills guereza Colobus guereza dodingae (n=3), olive baboon Papio anubis (n=30), eastern patas monkey Erythrocebus patas pyrrhonotus (n=6), Budgett’s tantalus monkey Chlorocebus tantalus budgetti (n=5), Hilgert’s vervet monkey Chlorocebus pygerythrus hilgerti (n=7), savanna monkey Chlorocebus sp. (n=3), Stuhlmann’s blue monkey Cercopithecus mitis stuhlmanni (n=23), and Kolb’s monkey Cercopithecus mitis kolbi (n=2).
Nocturnal primates were encountered at 0.14 individuals/km and 1.20 individuals/h (n=12 individuals) during vehicle surveys and 0.38 individuals/km and 0.50 individuals/h (n=3) during foot surveys. Two genera, two species, and two subspecies were encountered; eastern potto Perodicticus potto ibeanus (n=2) and Senegal lesser galago Galago senegalensis senegalensis (n=24).
Colobus g. dodingae, was found in Agoro-Agu Forest Reserve (FR), central north Uganda. This finding is important as it (1) reduces the list of endemic primate subspecies in South Sudan by one; (2) is an additional primate subspecies for Uganda and East Africa; and (3) establishes C. g. dodingae as one of the most threatened primate subspecies in Uganda and East Africa.
Two groups of C. g. occidentalis were encountered in Otzi East Central Forest Reserve (CFR). This is the first record of this species for this forest. The Otzi Mts. represent the northeast limit for C. g. occidentalis. The White Nile River is the geographic barrier that separates C. g. occidentalis in the west from C. g. dodingae in the east.
Pan t. schweinfurthii, discovered in Otzi East CFR in 1993, was not encountered, and only indirect evidence of its (past) presence found. Residents claimed that P. troglodytes sometimes occupy Mt. Nyeri (Otzi East CFR) but seasonally move up Mt. Nyeri and into South Sudan’s Nimule National Park (NP). None of the residents interviewed had seen or heard chimpanzees within the last 3 years.
A group of P. anubis was observed at 2,738 m above sea level (asl) on Mount Elgon NP, west Kenya. The previous altitude record for P. anubis in East Africa is 2,550 m asl.
Six groups of E. p. pyrrhonotus were encountered during this survey, all in Kidepo Valley NP. Reports were obtained of presence in seven other areas.
Four groups and one individual C. t. budgetti were encountered. Four groups and three solitary individuals C. p. hilgerti were encountered. All individuals encountered (solitary or within a group) were shy.
Cercopithecus m. stuhlmanni was encountered in and near Agoro-Agu FR. Residents said this monkey is present within and near Kidepo Valley NP. These localities are near the north limit for C. m. stuhlmanni. Cercopithecus mitis on Mt. Elgon is considered by some authorities to be C. m. elgonis. Based on preliminary phenotypic analysis we suspect that elgonis is not a valid subspecies, and that C. m. elgonis is best placed as a synonym of C. m. stuhlmanni.
Perodicticus i. ibeanus was encountered twice in Teressa Forest Reserve (FR), southwest Kenya. This is a new locality record for this species but well within the known geographic range.
Galago s. senegalensis was found at three sites in north Uganda (Kidepo Valley NP, Agoro-Agu FR, and Otzi East CFR), and at one site in southwest Kenya (Teressa FR). All four localities are new for this subspecies but well within the known geographic range.
Fifteen genera, 24 species, and 18 subspecies of primate occur in Uganda. Six species (25%) and seven subspecies (39%) were assessed as ‘Threatened’ during the IUCN/SSC African Primate Red List Assessment Workshop in Rome (April 2016). Of these, two species are ‘Critically Endangered’; robust chimpanzee Pan troglodytes and eastern gorilla Gorilla beringei.
The future for most primate taxa in northeast Uganda appears bleak. Overall, primate densities are low, populations are small and fragmented, and the individuals of all taxa are shy and wary of humans. Primates are hunted over all of northeast Uganda and people are generally intolerant of primates outside protected areas.
The pressure on the few remaining forests of northeast Uganda is very high due to a growing scarcity of natural resources in the face of a human population that is doubling every 20–25 years. Frequent bush fires, logging, collection of poles and firewood, charcoal production, and agricultural encroachment into protected areas, are all contributing to the degradation, loss, and fragmentation of the natural habitats of this region, particularly the woodlands and forests. In addition, primates are hunted for meat and in response to crop raiding. These threats are of particular concern for forest-dependent species.
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