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.”
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°).
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.
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).
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.
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.”
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).
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.
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.