Yvonne de Jong is a National Geographic grantee working to track down what may be Africa’s least understood large animal, the Desert Warthog.
During our research to better define the geographical range of the desert warthog in northern Kenya, we use every opportunity to collect data on other taxa present in this dry and relatively poorly known region. The nights, in particular, provide new and interesting findings…and, this time, we are not talking ‘pigs’ (see our two earlier blogs).
A few hours after dark…in an oasis dominated by acacia and doum palm in the Chalbi Desert, we carefully scan each thorny bush and tree with our headlamps. It does not take long before we see the first bright orange shine of eyes peeking our way…..galagos! With our binoculars and flashlights we rapidly confirm the presence of the Somali lesser galago (or ‘bushbaby’)….Kenya’s least known primate and one of the five species of galagos found in this country.
The Somali lesser galago (scientific name: Galago gallarum) is a nocturnal, arboreal, primate of the thornbush and woodland of north-eastern Kenya, southern Ethiopia, and Somalia, but the limits of its distribution remain poorly understood. This small primate lives in dryer habitats (<400 millimeters/years) than any other primate in Africa. By adopting a ‘moisture-saving’, nocturnal lifestyle it meets its water needs from the foods that it eats. With its big eyes and ears, and beautiful orange limbs, this tiny (200 grams) primate is almost ‘too cute’ (not very scientific…we know) for the hostile, dry and heavily thorned habitat in which it thrives. They are able to move through the thorniest vegetation at speed, and can make leaps of up to 2.5 meters. Little is known about the diet of the Somali lesser galago but we have seen them feed on tree gum and insects, and strongly suspect that they occasionally eat fruits.
The Somali lesser galago was described and named over 110 years ago (1901) and later subsumed as one of the many subspecies of the northern lesser (Senegal) galago (Galago senegalensis). In the 1980s this taxon was elevated back to species level but its natural history remains poorly known. Since 2003 we have been collecting information on the distribution, abundance, ecological, behavior and conservation status of this species. Some of our findings are now published (see www.wildsolutions.nl ).
Our first encounter with the Somali lesser galago was in 2003 in Meru National Park, north of the Tana River, central Kenya. We have since confirmed the presence of this species at many sites in southern Ethiopia and in northern, central and eastern Kenya. Our finding, thus far, suggest that the south-western limit for the Somali lesser galago is the Tana River (Kenya’s largest river), that the central-western limit is the Kenya Highlands, and that the north-western limit is the Chalbi Desert and the Ethiopian Highlands. The eastern and north-eastern limits, and probably the greater part of the geographic range of this species, lie in Somalia and in south-eastern Ethiopia, but galagos have never been surveyed over that vast region.
Confirming the presence of the Somali lesser galago in the south-eastern part of the Chalbi Desert is important in several respects. First, it provides a ‘dot on the map’ near the middle of a 200 kilometer wide stretch of desert that we suspected was too dry for this galago (200 to 400 millimeters of rain per year) (see map at www.wildsolutions.nl). It also indicates that the Somali lesser galago can occupy small, extremely isolated, patches of acacia bush and woodland. As there are currently no subspecies described for the Somali lesser galago, observations of the colour and pattern of the pelage of individuals from distant parts of the range, and from isolated sites like this oasis, could be especially rewarding since differences would suggest the existence of subspecies.
Galagos produce a wide range of calls. Their ‘loud calls’ — an aid in nocturnal, long-distance, spacing and territoriality — can be heard by the human ear as far as 300 metres. Each species produces a distinctive loud call (or advertisement call) and this is used by primatologist to identify species. When we first heard the loud call of the Somali lesser galago we were surprised at how different it was from that of the Senegal lesser galago, particularly since the two were, for many years, considered to be of the same species. The Senegal lesser galago emits a single-unit, low pitched loud ‘honk’ (or ‘woo’) call that is repeated in long series at about 1-2 second intervals. The Somali lesser galago produces a rapid four unit, explosive ‘quack’ that is usually repeated many times and grades into three, two and one unit calls.
We have observed several behavioural differences between these two species of galagos. For example, the Somali lesser galago is typically much more confiding and less shy than the Senegal lesser galago. On being located with a light, the Somali lesser galago frequently moves towards the observer, sometimes to as close as 1 meter. The Somali lesser galago often forages on insects that are attracted to the light of our lamps. The Senegal lesser galago, in contrast, is generally shier and usually moves away from the observer to hide in a tree hole or in dense vegetation.
The Somali lesser galagos that we observed in the oasis of the Chalbi Desert were not much bothered by our presence. They gave us good photographic opportunities and views with our binoculars. We were able to confirm that they had grey hands and feet, like those 170 kilometers to the south, at the foot of the Mathews Range, not black hands and feet like those in Meru National Park, 310 kilometers to the south-east.
That night we placed our tents under the canopy where the galagos were active. I fell asleep with my hand on the RECORD button of the audio recorder…hoping to capture the galago’s loud call. That was not to be! Instead there would be spotted hyenas sniffing at our tents and calling nearby. Nonetheless, we were well pleased with discovering the Somali lesser galago at this site, and with the new dot on the distribution map.
For galago photographs, maps, literature and research project details, visit www.wildsolutions.nl