Research Projects
Northeast Kenya Antelope Survey

Gunther’s dik-dik (Madoqua guentheri) north of Marsabit, northern Kenya
Completed March 2024
Determine the taxonomic status, distribution, relative abundance, and threats of the antelopes of northeast Kenya, provide information for the next IUCN Red List reassessments of their degree of threat status, provide recommendations for ameliorating the threats and bring attention to the unique biodiversity of this region.
Final report: Butynski & De Jong 2024
This survey is funded by the Zoologische Gesellschaft für Arten- und Populationsschutz (ZGAP).
Mahale Mountains National Park: Tourism Development and Ranger and Guide in Research Methods
April 2022 – August 2023
From 12–23 April 2022, we conducted a training course on natural history and large mammal monitoring in Mahale NP for eight guides and trackers from Greystoke Mahale and five Tanzania National Park (TANAPA) rangers. An undescribed subspecies of Colobus angolensis has only been observed three times by scientists (1976, 1979 and 2022) in Mahale Mountains National Park, central west Tanzania. During this exercise we encountered this undescribed primate and formally named it as the Mahale Angola colobus Colobus angolensis mahale (De Jong and Butynski 2023).
This exercise was supported by Tanzania National Parks, Nomad Tanzania, and Re:wild
Primates of East Africa: Pocket Identification Guide (Second Edition)
The second edition of the Primates of East Africa Pocket Identification Guide became available in May 2023, five years after the first edition (De Jong and Butynski 2018). The second edition recognizes 73 taxa. As for the first edition, the second edition is part of Re:wild’s Tropical Pocket Guide Series (series editors: Russell A. Mittermeier and Anthony B. Rylands) and is illustrated and designed by Stephen D. Nash. The second edition includes 13 QR codes to the vocal profiles of the galagos of East Africa. These were compiled by the Nocturnal Primate Research Group at Oxford Brookes University (Bearder et al. 2013). The second edition adopts the current degree of threat status of these primates as provided by the IUCN Red List of Threatened Species (IUCN 2023). The main differences between the first edition (2018) and second edition (2023) are depicted in De Jong and Butynski (2023)

Adult male desert warthog Phacochoerus aethiopicus at Suyian Ranch, Laikipia, central Kenya
Biogeography and conservation of desert warthog Phacochoerus aethiopicus and common warthog Phacochoerus africanus in the Horn of Africa
Ongoing project
Knowledge of the distributions, habitats, and environments of the desert warthog Phacochoerus aethiopicus and common warthog Phacochoerus africanus in the Horn of Africa (HoA) is essential for their conservation yet poorly understood. In this study we provide an overview of the biogeography and conservation status of these two species in the HoA.
De Jong, Y.A., d’Huart, J.-P. & Butynski, T.M. (2018). Biogeography and conservation of desert warthog (Phacochoerus aethiopicus) and common warthog (Phacochoerus africanus) in the Horn of Africa. 12th International Symposium on Wild Boar and Other Suids, Lázně Bělohrad, Czech Republic.

Somali lesser galago Galago gallarum. Drawing by Stephen Nash
Primates of Northeast Africa: Pocket Identification Guide
The Pocket Identification Guide of Northeast Africa (here taken as Djibouti, Ethiopia, Eritrea, Somalia, South Sudan, Sudan) includes 10 genera, 18 species, and 28 taxa of primates. For an additional 3 genera and 4 species it is uncertain as to whether they occur in this region. Illustrations in this Pocket Identification Guide are by Stephen Nash. Funded by Primate Action Fund.
Primates of East Africa: Pocket Identification Guide

Adult male southern patas monkey Erythrocebus baumstarki, Serengeti NP, Tanzania. Photograph by Richard Hoare & Sian Brown.
Distribution, Taxonomy and Conservation of the Southern Patas Monkey Erythrocebus baumstarki
Ongoing project
The geographical range of the southern patas monkey Erythrocebus baumstarki is poorly understood. Locality data are obtained from the literature and communications with other researchers, rangers, tour guides, naturalist, etc to reassess their historic distribution and update their current range and conservation status.
Have you seen patas monkeys in eastern Africa? To send us a reports of your encounters, click here!

Tana River red colobus Piliocolobus rufomitratus, Ndera Conservancy, Lower Tana River, Kenya
Current taxonomy, biogeography, and conservation of Africa’s colobine monkeys (Cercopithecidae, Colobinae)
Within the order of primates, the colobus monkeys of Africa represent one of the most threatened groups. In this study we assess the current taxonomy, biogeography, conservation status, and threats for Africa’s colobines, as well as recommendations for research and conservation action.
Natural History of the Somali Lesser Galago (Galago gallarum)
Ongoing project

Somali lesser galago (Galago gallarum), Chalbi Desert, Kenya
The Somali lesser galago (or Somali bushbaby) (Galago gallarum) is one of Africa’s least known primates. Field observations, literature reviews and museum visits are being undertaken to obtain information on the natural history of the Somali lesser galago. This project reviews what is known about the taxonomy, distribution, abundance, ecology, behaviour, and conservation status of the Somali lesser galago.
Butynski, T.M. & De Jong, Y.A. 2004. Natural history of the Somali lesser galago (Galago gallarum). Journal of East African Natural History 93: 23-38.
De Jong, Y.A. & Butynski, T.M. 2004. Life in the thornbush – the Somali bushbaby. Swara 27 – 22.
The Manyara Monkey: A New Subspecies of Monkey Endemic to Tanzania

Manyara monkey Cercopithecus mitis manyaraensis, Lake Manyara NP, Tanzania
Completed 2020
In Primate Conservation (Issue 34, April 2020), Butynski and De Jong review the taxonomy and distribution of the eight subspecies of Gentle monkey Cercopithecus mitis and describe a new subspecies endemic to central north Tanzania, the Manyara Monkey Cercopithecus mitis manyaraensis. This new subspecies is named after Lake Manyara which lies near the centre of its geographic range.
Primates of East Africa, Pocket Identification Guide
Completed 2018
Pocket Identification Guide with 70 taxa, 32 distribution maps and 73 drawings by Stephen Nash. Funded by Global Wildlife Conservation.

Mount Kilimanjaro guereza colobus monkey Colobus caudatus
Geographic range, taxonomy, and conservation of the Mount Kilimanjaro guereza colobus monkey Colobus caudatus
Completed 2018
The aim of this project was to assess the geographic range and conservation status of the Mount Kilimanjaro guereza, referred to as “Colobus guereza caudatus Thomas 1885”. This monkey is geographically very isolated, and phenotypically distinct from all other taxa of guereza monkeys. Application of the “Phylogenetic Species Concept” resurrects the Mount Kilimanjaro guereza to specific rank as Colobus caudatus.
Butynski, T.M. & De Jong, Y.A. 2018. Geographic range, taxonomy, and conservation of the Mount Kilimanjaro guereza colobus monkey
(Primates: Cercopithecidae: Colobus). Hystrix 29 (1): 81–85.
Biogeography, Taxonomy, Abundance, and Conservation Status of the Primates of North-eastern Uganda
Completed 2017

Northern lesser galago (Galago senegalensis) at Agoro-Agu Forest Reserve, Imatong Mountains, central-north Uganda.
The biogeography, taxonomy, abundance, and conservation status of non-human primates in northeast Uganda remain poorly-known. The main goal of this project is to contribute towards the long-term conservation of the primates of northeast Uganda by obtaining the scientific information needed for assessing conservation status and for setting conservation priorities. The primary objectives of this primate survey are to: (1) Determine, to the subspecies level, which taxa of primate occur; (2) Obtain preliminary information on distribution, relative abundance, and habitat for each primate taxon; (3) Establish a baseline against which long-term trends in distribution and abundance can be assessed; (4) Determine the conservation status of all primate taxa and work with the Uganda Wildlife Authority and others to set priorities for the conservation of primates in northeast Uganda. Meeting these objectives is expected to stimulate interest in primate research and conservation in northeast Uganda, and improve on the current IUCN Red List assessments for those primate taxa that occur.
Research project funded by the National Geographic Society.
Some of the research findings are published on our National Geographic Blog
Read ‘Update from the Field’
Read also: Technical report
Historic and current distribution, abundance, and habitats of Roosevelt’s sable antelope Hippotragus niger roosevelti in Kenya
Completed 2015
ABSTRACT: Roosevelt’s sable Hippotragus niger roosevelti is one of Kenya’s most distinctive and threatened large mammals. Historically, sable herds occurred in the vicinity of Taveta, and in the miombo and Diospyros woodlands of the coastal hinterland from the Tanzania-Kenya border northward for at least 210 km. Most of the historic distribution of sable in Kenya lies 15–35 km inland from the coast at 100–200 m altitude where mean annual rainfall is 800–1200 mm. In terms of numbers, however, most sable occurred in the higher and wetter Shimba Hills (150–460 m; mean annual rainfall 1000–1200 mm). Bachelor males sometimes moved >150 km inland. Much of the decline of
the distribution and size of Kenya’s sable population occurred during 1950–1980. Sable in Kenya not reported outside of Shimba Hills National Reserve after 1994. Geographic distribution of sable herds in Kenya declined from roughly 5000 km² in 1884 to 70 km² today (>98% decline in 132 years). The number of sable in Kenya was already small as of 1884, when there were probably <400 individuals. Kenya’s sable population declined from >235 individuals in the mid-1970s to ca. 60 individuals in 2015 (>74% decline in 40 years). Given the low number, small distribution, and rapid decline, sable in Kenya qualifies as a nationally ‘Critically Endangered’ species. Recommendations for the conservation of sable in Kenya are provided.
Butynski TM, Parker I & De Jong YA 2015. Historic and current distribution, abundance, and habitats of Roosevelt’s sable antelope Hippotragus niger roosevelti (Heller, 1910) (Cerartiodactyla: Bovidae) in Kenya. Journal of East African Natural History 104(1&2): 41–77.
Distribution, Abundance, Ecology and Conservation Status of the Desert Warthog Phacochoerus aethiopicus, Central South Kenya
Completed 2014

Common warthog (Phacochoerus africanus) in Tsavo East National Park, central south Kenya
The primary objectives of this project were to: (1) Obtain information on the distribution and abundance of desert warthog Phacochoerus aethiopicus and common warthog Phacochoerus africanus in central south Kenya; (2) Establish a baseline against which long-term trends in distribution and abundance of both warthog species can be determined and evaluated for the region; (3) Reassess the conservation status of both warthog species for the region.
Research project funded by Zoo New England.
Biogeography and Conservation Status of the Eastern Patas Monkey Erythrocebus patas pyrrhonotus in eastern Laikipia, Kenya
Completed 2014

Eastern patas monkey (Erythrocebus patas pyrrhonotus)
To manage Laikipia’s patas monkey population, it is important to monitor changes in its distribution and size. Patas surveys were conducted in Laikipia in 1979–1981 and 1992–2004. The Eastern Africa Primate Diversity and Conservation Program, in cooperation with the Lolldaiga Hills Biodiversity Research Program, is currently conducting a third survey of this population. As for the previous two surveys, much of the data will be obtained through a questionnaire. All owners/managers of large properties in Laikipia are invited to take a few minutes to complete the below questionnaire.
Have you seen patas monkeys in Laikipia or elsewere in East Africa? To send us a reports of your encounters, click here!
Read also ‘Survey of the Patas Monkey in Laikipia’
Read also: Technical report
Distribution, Abundance, Ecology and Conservation Status of the Desert Warthog Phacochoerus aethiopicus, Northern Kenya
Completed 2014

Desert warthog (Phacochoerus aethiopicus), Meru National Park, Kenya
The primary objectives of this project were to: (1) Obtain information on the distribution and abundance of Phacochoerus aethiopicus and Phacochoerus africanus in northwestern and central north Kenya; (2) Establish a baseline against which long-term trends in distribution and abundance of both warthog species can be determined and evaluated for the region; (3) Obtain a large body of new ecological and behavioral data; (4) Reassess the conservation status of both warthog species for the region.
Research project financed by the National Geographic Society. For more information read our blogs on the National Geographic Explorers Website
Survey of the Primates of the Loita Hills, Kenya
Completed 2012

Hilgert’s vervet monkey (Chlorocebus pygerythrus hilterti)
The principal aims of this survey in the Loita Hills (central south Kenya) were to (1) determine, to the subspecies level, which primate taxa are present; (2) Obtain information on distribution and abundance of each primate taxon; (3) Obtain basic ecological information on each primate taxon (e.g., altitudinal limits, habitats used, group size); (4) Establish a baseline for the long-term monitoring of the status of each primate taxon; (5) Assess the treats to each primate taxon; and (6) Assess the conservation status of each primate taxon and, if necessary, make recommendations for conservation actions and research.
Primate Survey of the North Coast of Kenya: Biogeography, Diversity and Conservation
Completed 2011

Three of the primate species of the coastal forests of Kenya
The principal aims of this survey of the north coast of Kenya were to (1) Document which species of primates and other large mammals are present; (2) Assess the geographic range and altitude limits of the primates; and (3) Examine intra-specific variation (phenotypic, vocal, habitat-use, etc.) for the primates. In addition, this assessment was designed to provide a rough indication of relative abundance and a baseline against which to monitor change.
Description of Sykes’s Monkey Cercopithecus mitis x Vervet Monkey Chlorocebus pygerythrus Hybrids in Kenya
Completed 2010

Adult male Sykes’s monkey x vervet monkey hybrid, Diani, Kenya
Natural hybrids have been reported for several species of African primates. An adult male monkey that is believed to be a Sykes’s monkey Cercopithecus mitis x vervet monkey Chlorocebus pygerythrus hybrid was found at Diani, Kenya, in December 2008. This is both the first record of a hybrid between these species as well as between these genera. Two other C. mitis x C. pygerythrus hybrids are described.
Assessment of the Primates, Large Mammals and Birds of the Mathews Range Forest Reserve, Central Kenya
Completed 2010

Pearl-spotted owlet (Glaucidium perlatum), Mathews Range, Kenya
The Mathews Range Forest Reserve (ca. 940 km²) lies within the Namunyak Conservancy (ca. 3332 km²) and is the southern-most of the forest-covered chain of mountains that crosses the semi-arid plains of Samburu District in north-central Kenya. Knowledge of the biodiversity of the Mathews Range is sparse and scattered. From 2 – 14 June 2010, 278 km (128 h) of foot and vehicle surveys were undertaken in the Mathews Range and adjacent parts of Namunyak Conservancy. The principal aims of this survey were to (1) Document which species of primates, large mammals and birds were present and obtain an indication of abundance; (2) Determine the habitat used and altitude limits for these species; (3) Assess intra-specific variation (phenotypic, vocal, habitat-use) between the primate species of the Mathews Range and conspecifics at other sites; (4) Establish a baseline against which to monitor change; and (5) Assess threats to the biodiversity of the Mathews Range.
Assessment of the Diversity and Conservation Status of Primates in the Coastal Forests of Kenya
Completed 2009

Peter’s Angola colobus (Colobus angolensis palliatus) at Diani, southeast Kenya
Although primates represent one of the best-known taxonomic groups found in the coastal forests of Kenya, numerous important questions remain concerning their taxonomy, distribution, abundance, conservation status, and priorities for conservation actions.
The main aim of this project was to assess primate diversity, distribution, taxonomy and the conservation status of all primates in the coastal forests of Kenya.
Research project supported by the Critical Ecosystem Partnership Fund.
Body Measurements for the Monkeys of Bioko Island, Equatorial Guinea
Completed 2009
This article presents the first large set of body measurement data for each of the seven species of monkeys endemic to Bioko Island; means, ranges, standard deviations and sample sizes for seven body measurements. These 49 data sets derived from 544 fresh adult specimens (235 adult males and 309 adult females) collected by shotgun hunters for sale in the bushmeat market in Malabo.
Guide Training and Expansion of Nature Tourism Activities at Greystoke-Mahale, Tanzania
Completed 2009

Eastern chimpanzee Pan troglodytes schweinfurthii, Mahale Mountains National Park, western Tanzania
The aim of this project was to help establish Greystoke-Mahale itself as one of the premier primate-viewing and montane forest tourism destination in Africa.
See Greystoke Mahale Guide and Tracker Blog for natural history information for Mahale Mountains National Park.
Description of a New Potto Perodicticus potto stockleyi in Kenya
Completed 2006
The potto Perodicticus potto is a small, arboreal, nocturnal primate with an extensive, but poorly-known, distribution through tropical Africa, and a debated taxonomy. This project (1) examined the Eastern Rift Valley as a major barrier to primate distribution in eastern Africa, (2) reviewed the taxonomy of P. potto, (3) described the distribution of the eastern potto P.p. ibeanus, (4) summarized what is known about the body size, abundance, elevation and rainfall limits of P.p. ibeanus, (5) provided evidence for the presence of P. potto east of the Eastern Rift Valley, and (6) described, named, and discussed a new subspecies of Perodicticus for Mount Kenya (the ’Mount Kenya potto’ Perodicticus potto stockleyi).
Butynski, T. & De Jong, Y. 2004. Where are Kenya’s potto’s. Swara 27: 17.
Taxonomy, Distribution, and Conservation Status of Three Species of Dwarf Galagos (Galagoides) in Eastern Africa
Completed 2006

Juvenile Kenya coast galago Galagoides cocos, Mpeketoni, Kenya
This study reviewed the complicated nomenclatural history for the Kenya coast galago, Galagoides cf. cocos, and examined whether ‘cocos’ is the valid species name for this recently resurrected taxon. It also reviewed the phenotypic and vocal differences among G. cocos; the Zanzibar galago (Galagoides zanzibaricus zanzibaricus); the Udzungwa galago (Galagoides zanzibaricus udzungwensis); and the Mozambique galago (Galagoides granti), as well as their geographic ranges and conservation status.