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Discoveries From Two Years With Kenya’s Warthogs

Yvonne de Jong & Thomas Butynski

In December, 2012, we began our quest to better understand one of Africa’s least-known large mammals: the desert warthog (Phacochoerus aethiopicus).

Over the following two years we shared the findings from our project here on the Explorers Journal blog, revealing observations not only of warthogs, but also of several other species. This project has now come to an end, so we present a brief overview of what we discovered on our “Quest for Kenya’s Desert Warthog.”

Tom Butynski inspecting a dry river bed in Turkana for warthog footprints. Photograph by Yvonne de Jong.
Tom Butynski inspecting a dry river bed in Turkana for warthog footprints (Photo by Yvonne de Jong)

The Lay of the Land

Together, northern and central Kenya support vast areas of desert, savannah, lava rock plain, sparsely wooded grassland, shrubland, and patches of mid-altitude forest and montane forest. In the area covered by this survey (no less than 128,000 sq. km), all of these ecosystems are represented. The altitude ranges from 260 m above sea level (Kora National Park, Tana River County) to 3,060 m asl (Cherangani Hills, Trans Nzoia County). Due to security issues in northern Kenya, few ground surveys of the larger mammals have been conducted in the past. For this same reason, we were somewhat restricted in our movements through the region and we had to avoid northeastern Kenya.

This survey comprised a total of 8,463 km and 623 hours during 47 field days. The desert warthog was not found in northwest Kenya, is rare in central-north Kenya, and is locally common in central Kenya. We did not find evidence for the desert warthog west of the Eastern (Gregory) Rift Valley; the known western limit lies just west of Baragoi (E 36.810°).

Geographical range of the desert warthog (Phacochoerus aethiopicus) and common warthog (Phacochoerus africanus), and areas of sympatry, in Kenya. The extent of occurrence is based on the localities presented in WarthogBase and on the findings (depicted) of this project. Question marks indicate areas which require surveys. Map compiled by Yvonne de Jong & Tom Butynski.
Geographical range of the desert warthog (Phacochoerus aethiopicus) and common warthog (Phacochoerus africanus) , and areas of sympatry, in Kenya. The extent of occurrence is based on the localities presented in WarthogBase and on the findings (depicted by triangles) of this project. Question marks indicate areas which require surveys. (Image created by Yvonne de Jong & Tom Butynski)

Widening the Range

We encountered a sounder of six desert warthogs at Mt. Forole in northern-central Kenya. This is the first known report of the species being present on Mt. Forole. This encounter resulted in an extension of the known range of the desert warthog about 120 km to the west (the nearest record in our database is Moyale). Although we did not capture any warthogs during 308 hours of camera trapping in this area, footprints were common, indicating that the warthogs were more numerous than our encounter rate suggested (read more in “Photos: Biodiversity of Northern Kenya´s Huri Hills and Mt. Forole“). During “non-survey” visits to Samburu NR and Meru NP,  we saw an additional 15 desert warthogs.

No warthogs were captured by camera traps at Mt. Forole, near the Ethiopian border in central north Kenya. They did, however, capture aardvarks (Orycteropus afer). Burrows dug by aardvarks are used by warthogs, providing them with protection from predators as well as an environment with favorable temperature and humidity. By Tom Butynski and Yvonne de Jong.
No warthogs were captured by camera traps at Mt. Forole, near the Ethiopian border in central north Kenya. They did, however, capture aardvarks (Orycteropus afer). Burrows dug by aardvarks are used by warthogs, providing them with protection from predators as well as an environment with favorable temperature and humidity. (Photo by Tom Butynski and Yvonne de Jong)

The common warthog (Phacochoerus africanus) is uncommon in northwest and central-north Kenya, and locally common in central Kenya. A total of 70 common warthogs were counted during this project. During road surveys and with the help of our camera traps we confirmed common warthogs in Marsabit County. With the confirmation of the common warthog in the Loima Hills, the geographical range of this species west of Lake Turkana has been extended about 200 km to the north (from Mt. Elgon in central-west Kenya).

Camera trap photograph of a sounder of common warthogs (Phacochoerus africanus) in South Turkana National Reserve, Turkana County, northwest Kenya. By Tom Butynski and Yvonne de Jong.
A camera trap photograph caught a sounder of common warthogs (Phacochoerus africanus) in South Turkana National Reserve, Turkana County, northwest Kenya. (Photo by Tom Butynski and Yvonne de Jong)

Despite all of the reports from residents, we did not encounter any warthogs poking about during our surveys in Pokot County. As the habitat seems highly suitable for warthogs, it is likely that a low-density population is present. It is unknown which species of warthog is present, but given the known proximity of the common warthog, and the absence of records for the desert warthog west of the Chalbi Desert, the species here is likely the common warthog.

Erosion on the northern foothills of the Cherangani Hills, Marich Pass, West Pokot County, northwest Kenya. Photograph by Yvonne de Jong and Tom Butynski.
Erosion on the northern foothills of the Cherangani Hills, Marich Pass, West Pokot County, northwest Kenya. (Photo by Yvonne de Jong and Tom Butynski)

The Biggest Surprises

As indicated on the distribution map above (and as mentioned in our earlier blog post, “Warthogs and Primates in the Meru Conservation Area, Central Kenya, and the Decline of Kora National Park“), we now know that the distribution of the two species of warthog are sympatric (they overlap) at three sites; central Kenya (about 8,700 sq. km), central-southern Kenya (about 6,900 sq. km), and eastern Kenya (about 3,900 sq. km). The fact that the two species live side by side indicates that they occupy different ecological niches.

Rather surprisingly, this project found that the common warthog can live in more arid environments than the desert warthog. That these areas lack year-round surface water indicates that common warthogs can survive for several months without drinking water, and that they are less dependent on drinking water than the desert warthog. The common warthog lives under a much wider range of annual rainfall and altitude than does the desert warthog and, therefore, has a much greater geographic range than the desert variety. Nonetheless, there are sites (all at low altitudes) where the desert warthog dwells in the absence of the common warthog (i.e. southeastern and central-eastern Kenya).

Common warthog (Phacochoerus africanus) sounder in South Turkana National Reserve, Turkana County, northwest Kenya. We found no evidence of desert warthogs (Phacochoerus aethiopicus) in Turkana County. (Photo by Yvonne de Jong and Tom Butynski)

Common warthogs are described as diurnal in scientific literature. At night, and during the hot hours of the day, they typically seek shelter. This project revealed, however, that this species is, at least sometimes, active during the night. Read more in our blog “Where Warthogs Roam at Night.”

Camera trap photograph of a sounder of at least two adult and six young common warthogs (Phacochoerus africanus) in riverine forest south of Sibiloi National Park (595 m asl), central northern Kenya. No surface water was found in this area. Dense clumps of doum palms (Hyphaene thebaica) are, however, present. We suspect that its fruits are a vital food and source of water for common warthogs, olive baboons (Papio anubis), northern crested porcupines (Hystrix cristata), and other species. By Tom Butynski and Yvonne de Jong.
Camera trap photograph of a sounder of at least two adult and six young common warthogs (Phacochoerus africanus) in riverine forest south of Sibiloi National Park (595 m asl), central-northern Kenya. No surface water was found in this area. Dense clumps of doum palms (Hyphaene thebaica) are, however, present. We suspect that its fruits are a vital food and source of water for common warthogs, olive baboons (Papio anubis), northern crested porcupines (Hystrix cristata), and other species. (Photo by Tom Butynski and Yvonne de Jong)

Warthogs and Humans

This project found that both species of warthog occur naturally at low densities in areas with a mean annual rainfall of less than 500 mm. Both species have declined in abundance and distribution in historic times. The main threats are poaching, competition with people and livestock for water, and habitat destruction, degradation and fragmentation as a result of the severe over-stocking of the range with livestock. Both species of warthog are shy and wary of humans as a result of poaching (particularly in predominantly Christian areas).

Yvonne de Jong scanning one of the several permanent rivers of Meru National Park, central Kenya. Photograph by Tom Butynski.
Yvonne de Jong scanning one of the several permanent rivers of Meru National Park, central Kenya (Photo by Tom Butynski)

Kenya’s human population, which in arid regions is largely dependent on livestock, is doubling about every 20 years. As a result, the fragile arid lands have been over-grazed and over-browsed for several decades, particularly in the vicinity of permanent water. Competition between wildlife and humans/livestock for water and food has become increasingly intense outside as well as within “protected” areas. We encountered livestock in all protected areas of northern and central Kenya, but densities were highest in Nasalot NR, Sibiloi NP, and Kora NP.

The diversity of large mammal species in all of these protected areas has been substantially reduced. Additional species will be lost over the coming decade unless these areas are better managed. If the encroachment of people with their livestock into protected areas is not stopped soon, there will be no future for wildlife and tourism in northern and central Kenya. If this happens, the people of these regions are expected to become increasingly impoverished.

Tom Butynski scanning the degraded savannah of southern Sibiloi National Park, northeast Kenya. Photograph by Yvonne de Jong
Tom Butynski surveying the degraded savanna of southern Sibiloi National Park, northeast Kenya. (Photo by Yvonne de Jong)

We are grateful to the National Geographic Society for kindly providing financial support to this project. To read the full project report, and see additional images taken during this project, please visit wildsolutions.nl.

Read All Posts by Yvonne de Jong and Thomas Butynski

Changing Planet

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Yvonne A. de Jong (PhD) is a Kenya-based Dutch primatologist who has worked in Africa for more than 13 years. She is member of the Nocturnal Primate Research Group at Oxford Brookes University, member of various IUCN/SSC Specialist Groups including the Primate and Wild Pig Specialist Groups, and Collaborating Scientist of the Institute of Primate Research in Nairobi. Her main research focus is the biogeography, diversity and conservation of eastern Africa's primates and several other groups of large mammals, including the warthogs. She is the co-leader of the Eastern Africa Primate Diversity and Conservation Program and senior ecologist at the Lolldaiga Hills Research Programme )Sustainability Centre Eastern Africa' based in Laikipia, Kenya. Thomas M. Butynski (PhD) is an American conservationist and ecologist who has worked in Africa for 45 years, mostly in Botswana, Kenya, Uganda, and Equatorial Guinea. He is a member of four IUCN/SSC Specialist Groups (Primates, Antelopes, Afrotheria, Wild Pigs) and has served as Director of the Institute of Tropical Forest Conservation in Uganda, Director of Conservation International’s Eastern Africa Biodiversity Hotspots Program in Kenya, Director of the King Khalid Wildlife Research Center in Saudi Arabia, Vice-Chair of the Africa Section of the IUCN/SSC Primate Specialist Group, Senior Editor of the journal African Primates, and a Senior Editor for Mammals of Africa. At present he is Co-leader of the Eastern Africa Primate Diversity and Conservation Program, and Director of Research at the Sustainability Centre Eastern Africa in Kenya.