SOUTHERN LESSER GALAGO
Geographic Distribution and Habitat
Southern lesser galago, also known as Mohol bushbabies, South African galagos, and South African lesser galagos, have a wide distribution ranging from northern Namibia and Angola, southeastern Democratic Republic of the Congo (DRC), Zambia, Zimbabwe, and northern Botswana to eastern Mozambique and the northern and northeastern parts of South Africa. Two subspecies are endemic to Burundi and Rwanda. The taxonomy of these two subspecies is somewhat controversial, with some scientists asserting that they are all, in fact, one species, while others assert otherwise. In any case, the countries in which all southern lesser galagos reside offer a wide variety of habitats that include woodlands, savanna woodlands, and gallery forests with differentiated seasons.
Size, Weight, and Lifespan
Southern lesser galagos weigh, on average, 5–9 ounces (150–250 g) with females being a tad lighter. They are 14–17 inches (34–44 cm) long including the tail, which measures 4–11 inches (11–28 cm).
They live up to 16 years in the wild.
These small primates have big round eyes adapted to night vision. They are recognizable from other galagos thanks to the white stripe that runs down their nose.
Their ears are very large and so flexible that they can bend in all directions and can move independently of one another—a very useful feature for hunting insects. The upper part of their body, their head, and the outer part of their limbs are covered in short and soft pale gray fur. The fur on their back can be light russet brown. Their belly is white, but the underpart of their limbs is a creamy yellow color. Their tail is a mix of gray and brown fur. They can easily climb vertically and leap from tree to tree because their muscular hind limbs are longer than their forelimbs.
Their rough and narrow tongue is well adapted to scraping gums and insects from tree holes and crevices and their tooth-comb helps them keep their fur free of parasites. The tooth-comb is a dental structure in the lower front jaw of some animals that are grouped as if to form a comb that is used by these animals to groom and clean their fur or hair.
Southern lesser galagos forage alone, smelling and licking the trees from which they feed. They favor gums exuding from Acacia trees—especially the Acacia karroo, also known as sweet thorn—which can grow and thrive in very dry conditions. Gums are an essential food item, especially in the winter (June and July). There are two types of gum: light and dark. Light gum is higher in sugar and therefore provides more energy. These small primates also eat arthropods and insects, like moths and butterflies, as well as other plant matter.
In highly fragmented habitats or in the winter when food is scarce and there are fewer insects, they have been observed supplementing their diet with fruit from Pappea capensis, a medium-sized deciduous tree commonly known as Jacket plum—the fruit of which is high in protein and fat.
The food galagos thrive on is difficult to process. Thankfully their digestive system is highly specialized. The ingested items ferment in the hindgut, which is filled with microbes; they are, therefore, able to absorb the nutrients they need.
Behavior and Lifestyle
These nocturnal primates are arboreal and are commonly observed in pairs or in small groups. The group composition is not static and changes in the winter and summer. A group’s home range is between 16 acres (6.7 ha) for females and 29 acres (12 ha) for males. The population density varies by location but tends to average between 12 and 30 individuals for 250 acres.
The southern lesser galago was identified as a distinct species by Sir Andrew Smith (1797–1872), a Scottish surgeon, explorer, and naturalist, while he ran an expedition in South Africa between 1834 and 1836. A century later, it was downgraded to a subspecies of the Senegal lesser galago. It recovered its unique species status in 1988 when zoologist Elke Zimmermann and her team proved how consistently different this galago’s loud call is from that of other galagos.
Southern lesser galago groups separate at night to forage. They wake shortly before or after sunset and remain active for 10 to 14 hours during the summer months and 6 to 11 hours during the winter. During the cold months, they have to travel longer distances to find suitable food items. In fact, females travel twice as far in the winter as they do during the summer. While they are active, they look for food but also take a few breaks to rest and play. When they do, pairs can be observed grooming and licking each other’s fur.
All individuals return to the sleeping site when the day starts. Their sleeping accommodations can take many forms—from abandoned bird nests to mats of foliage to tree hollows. Mothers sleep with their offspring. In the summer, most individuals rest alone on tree branches without covering, but in the winter all use tree holes and sleep in groups.
Sleeping together in a hollow in the winter can be a life saver. Indeed, bushbabies are endotherms—that is, they are able to generate their own heat and maintain a constant body temperature no matter what the outside temperature is. In the winter, when they are unable to find food (and only under such circumstances), southern lesser galagos go into a state of torpor, during which their body temperature is at its lowest, 66 F (19 C) or below. The warmth generated by another galago’s body or the heat they generate themselves through metabolism and minimal muscle movements allows them to survive, come out of the state of torpor, and resume normal activity.
Nocturnal primates do not use many visual cues to communicate, although these bushbabies are able to recognize one another by sight. For this reason, they communicate mainly through vocalizations and scent.
Their vocal repertory is rich and includes at least 25 individual calls. Contact calls (also referred to as long calls) are used to keep the group together and to let everybody know where everyone else is. Individuals only respond to contact calls uttered by a member of their own species. These calls are specific to each species and only members of the same galago species answer them.
Babies call their moms with a distress call. The mothers respond by retrieving them from their location and parking them somewhere else. “Parking” an infant refers to mothers leaving their young alone in the nest at night usually while the mothers forage. Barks, which sound like double or triple sequences of the same note, serve to bring the group back together. Males or females use barks, but the tone and intensity is specific to each individual.
Males hoot when they approach females. When they are anxious, they express it differently depending on how fearful they are. A sneeze is indicative of low stress; a shivering shutter or rapid knocking is a mild alarm. High stress levels are expressed through explosive coughs, clucks, and yaps, whereas plaintive calls sound like whistles or wails. During agonistic encounters, which usually occur at the borders of their territory, dominant males (the oldest) grunt, yap, and spit or scream. They also chase, grab, or bite their adversary while vocalizing. The loser escapes by running away.
Scent is another strong communication tool. Both males and females have glands on their sternum (the area located at the breastbone) and mouth that they rub against various surfaces and branches in the areas they live in to delineate their territory. They scent mark systematically when other galago species are in the neighborhood. These primates also practice urine-washing—they (mostly dominant males) wet their hands and feet in urine before participating in social grooming. The urine is therefore transferred to the fur of the group members who become easily identifiable by odor. Urine washing is common when the bushbabies enter a new location so they can saturate it with their own smell. This behavior may be associated with fear. The urine may also improve their grip for climbing up tree trunks.
The southern lesser galago is polygynous and the territory of dominant males overlaps with that of several females. Larger males are usually able to consort with all the females but smaller males are opportunistic and can find a few females willing to accept their courtship. These primates are biologically able to start a family at nine months old and males leave their native group at 10 months old, although they rarely reproduce until they reach the age of 15 months.
There are two mating seasons every year. Females show their readiness with a swelling that lasts about three days. Babies are born after 121 to 124 days of gestation, between January and February or between October and November. The first time they give birth, females have one offspring, but as they get older, they can have two sets of twins per year. The newborns are tiny creatures that weigh no more than a third of an ounce (10 g). They come into the world covered in fur and with their eyes wide open.
Males do not participate in infant rearing, but females are devoted to their offspring. Newborns are left in the nest for 10 days, then their mothers carry them around by the scruff of the neck for about 50 days. They nurse them for 11 weeks and park them in tree forks or in tangles of vegetation as they forage, during which time the babies are left alone for up to three hours; the mothers, however, check on them regularly and come right away to retrieve them if the babies call in distress. Although they are not weaned for about 90 days, they start catching insects at 4 weeks old.
Southern lesser galagos help keep insect populations in check by consuming them. Since they are fond of nectar, it is probable they also play a role in plant pollination. They also provide nutrition to predators.
The southern lesser galago is classified as Least Concern by the International Union for Conservation of Nature (IUCN, 2016). Overall their population is considered at low risk, but that varies by location.
In 2011, for instance, the estimated overall population of southern lesser galagos at the Loskop Dam Nature Reserve, South Africa, was between 300 and 1000 individuals with a density of less than 20 animals per thousand acres—fifty to one hundred times less than estimates from 1970. These early figures may have been inflated and inaccurate, but it is certain that populations of southern lesser galagos are decreasing everywhere due to habitat degradation caused by human activity.
The Loskop Dam is one such example. Built in 1939 and renovated in 1979, the dam provides water to farmland; however, it also imposes serious stress to microhabitats. High levels of toxins have also been found in those waters, which is known to negatively impact wildlife and human health. Where urban life is expanding, as in areas near Johannesburg and Pretoria, galagos find themselves in close proximity to humans and are starting to rely on food sources they would not otherwise access, such as crops. This is not only affecting their physiology (they are fatter than they would normally be) but also their natural behavior (they sleep longer and hang out in pairs or groups more often, which increases their stress hormone levels and therefore they are more aggressive).
Other factors, such as the illegal pet trade, bushmeat, or the sale of body parts for folkloric medicine, impact the species as well, but to a lesser extant to date.
Their natural predators include large birds (eagles and owls) as well as snakes, mongooses, civets, and genet cats.
Southern lesser galagos are listed on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), a multilateral treaty to protect endangered plants and animals.
Southern lesser galagos live in several protected forests and parks. Although the species is of widespread at this time, their survival will depend on diligent enforcement of rules aimed at preventing illegal logging, harvesting of fire wood, and other activities that could destroy their habitat. A systematic census of the species is also necessary to ensure that the location of groups and their numbers are accurate and help define conservation efforts as they may be needed in the near future.
- IUCN Red List
- African Primates 12: 1-8 (2017) – Species Density of Galago moholi at Loskop Dam Nature Reserve, South Africa – Ian S. Ray, Brandi T. Wren, Evelyn J. Bowers
- The Journal of Experimental Biology 216. 3811-3817 (2013)
- Nonshivering thermogenesis in the African lesser bushbaby, Galago moholi – Julia Nowack, Kathrin H. Dausmann and Nomakwezi Mzilikazi
- Whose Honk? Using Acoustic Playbacks to Test Species Recognition in Galagos – Caroline M. Bettridge, Selvino R de Kort
- The hustle and bustle of city life: monitoring the effects for urbanisation in the African lesser bushbaby – Juan Scheun, Nigel C. Bennett, Andre Ganswindt, Julia Nowack
- Spicing up the menu: evidence of fruit feeding in Galago moholi – Juan Scheun, Nigel C Bennett, Andre Ganswindt, Julia Nowack
- Surviving the Cold, Dry Period in Africa: Behavioral Adjustments as an Alternative to Heterothermy in the African Lesser Bushbaby (Galago moholi) – Julia Nowack, Marta Wippich, Nomakwezi Mzilikazi, Kathrin H Dausmann
- Vocal Profiles for the Galagos: A Tool for Identification – Simon K Bearder, Thomas Butynski and Yvonne A de Jong
- Galago moholi – Southern Lesser Galago – The Red List of Mammals – South Africa, Lesotho and Swaziland – Judith Masters, Fabien Génin, Simon Bearder
Written by Sylvie Abrams, June 2020