Tanzania Coast Dwarf Galago, Paragalago zanzibaricus
TANZANIA COAST DWARF GALAGO
Geographic Distribution and Habitat
The Tanzania Coast dwarf galago—also called the Matundu dwarf galago, the Udzungwa bushbaby, the Zanzibar bushbaby, the Zanzibar dwarf galago, and the Zanzibar galago—is native to the Unguja island, also known as Zanzibar island, and to mainland Tanzania. It dwells in riverine forests, coastal thickets, and the mid-to-high canopy of lowland and submontane forests.
On Unguja, most groups live in the southern half of the island and a few other groups live in the Kiwenga Forest Reserve in the north and the Masingini Forest Reserve in the west. Small groups have been identified as well on Uzi island in the south, which is connected by a causeway to Unguja island.
On the mainland, groups spread from the South Pare Mountains and East Usambara Mountains south to the Rufiji River and west to the Kihansi River in the Udzungwa Mountains.
When first encountered, the Tanzania Coast dwarf galago was classified as a Galagoide and named Galago zanzibaricus by 19th century German naturalist Paul Matschie. Recent DNA, morphology, and vocalization studies have led to reclassification in 2017 as the newer Paragalago genus, which includes small-bodied or dwarf galagos.
Size, Weight, and Lifespan
As its name indicates, the Tanzania Coast dwarf galago is quite small, with a weight of approximately 5–5.3 ounces (130–150 grams) and a length of less than 6 inches (14–15 cm). Its tail is almost as long as its body. Those who live on the mainland are a tad larger than those found on Zanzibar island.
Their life expectancy in the wild is unknown, but dwarf galagos in captivity can live up to about thirteen years.
The Tanzania Coast dwarf galago is covered in a thick pelage of gray to brown or cinnamon coloring. Its tail is characterized by sparse wiry hair through which the skin and bone structure are visible. The color of the tail varies between individuals and, for some, the tip of the tail is white. The thighs are very muscular and large compared to the overall body size. In fact, thigh muscles represent almost a quarter of this galago’s weight. It’s no wonder they can travel more than two and half yards (2.5 m) in a single jump.
The head is round with a pointy muzzle colored by patches of gray or brown. The nose is wet. The mouth is small and delicate with special comb-like incisor teeth that allow these galagos to scrape gums from acacia trees.
Big round eyes are perfectly adapted to night vision. Large bat-like ears (about 1.3 inches/3.3 cm long) give this dwarf galago exceptional hearing and the ability to track insects in the dark and catch them by hand with extreme accuracy. The hands and feet have five digits with rounded tips.
Tanzania Coast dwarf galagos feed mainly on insects, fruit, nectar, tree gums, and occasional small animals.
Behavior and Lifestyle
Tanzania Coast dwarf galagos are nocturnal (active at night), arboreal (tree-dwelling), and very shy—so they are difficult to observe in the wild. Females live in small groups and the population density varies depending on the location. In the Matundu Forest Reserve, it is estimated that over 500 individuals can be found per square mile (2.6 sq km), whereas at other sites, there may be fewer than 100. It is likely that Tanzania Coast dwarf galagos mark their territory like other galagos do, i.e., by urinating on their hands, thus spreading their scent as they leap between trees. They travel by walking, running, or leaping. When standing on branches, they grasp the branches with both hands and feet.
The Tanzania Coast dwarf galago can move each ear independently.
Like all members of the Paragalago genus, Tanzania Coast dwarf galagos sleep in tree hollows—alone or with a couple of companions—during the day. Groups share and reuse sleeping sites over time, but the same individuals do not necessarily go back to the same tree hole or hollow night after night. Sleeping sites offer shelter against predators and individuals have been observed adding leaves to them, thereby increasing camouflage and their safety.
When night falls, the groups get together after hearing an assembly call close to the nest site. They may join into a chorus before dispersing to go foraging and travel as much as one mile (1.6 km) each night.
Some have been observed grooming each other for long periods of time, which indicates grooming is one way in which they bond with other members of the group.
One way scientists are able to identify these small creatures is through their vocalizations. Each species of dwarf galago has a distinctive repertoire and more than ten loud calls.
Calls convey information about the caller’s identity, physical condition, location, and motivation. They vary in frequency and length. Calls may be mixed together in various sequences. There does not seem to be any difference between the structure of the calls uttered by males versus females, but vocalizations serve very specific functions.
Advertising calls are usually made by males to keep companions together and discourage rivals from getting near. Warning or mobbing calls, usually combined with chirrups and yaps, warn family members of danger. Yaps may break into screeches that last between 5 and 10 seconds. These are heard at night when the groups are active. Outside groups may respond by counter-calling. Buzzes indicate mild alarm and are short (1–2 seconds), whereas grunt-shrieks, which are low-volume calls made by swallowing air rapidly while screeching, indicate extreme alarm.
While foraging, partners sharing the same sleeping site usually keep in touch with loud, short contact calls. Each partner responds to the other with quick calls and sometimes they move toward each other. Infants usually call so their parent can come and retrieve them from where they are parked. Parking refers to mothers leaving their young alone in the nest at night while they forage.
The groups vocalize regularly during the night but they also have a gathering call before going to their sleep sites when morning comes.
Tanzania Coast dwarf galago females become mature and ready to breed at around 9 months of age. Males become mature at one year of age, at which time they leave their maternal group in search of mating partners. Mating groups usually include one male and two or more females. Breeding usually takes place between the months of July and March. Females give birth after three months of gestation. They can have one or two offspring each year.
Mothers carry their infant in their mouth and park them while foraging. They nurse them until the babies are about four months old.
As fruit eaters, Tanzania Coast dwarf galagos likely contribute to seed dispersal and therefore to the health of the forests they live in.
The Tanzania Coast dwarf galago is listed as Near Threatened (IUCN, 2019) on the International Union for Conservation of Nature’s Red List of Threatened species. This Near Threatened assessment is not because the current population is particularly low, but because the species is found in extremely fragmented forests. The concern is that, with their habitats so fragmented, species diversity and, therefore, their populations could rapidly plummet in the coming years.
Tanzania Coast dwarf galagos fall prey to several species of snakes including cobras, boomslangs, and green mambas. However, the real threat to their survival is loss of habitat. Human activities are destroying the forests to make space for subsistence and commercial agriculture, tree plantations, timber extraction, fuelwood, charcoal, and manufacturing.
The Tanzania Coast dwarf galago species is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES). Better information on where members of the species live is needed to truly assess their situation.
Fortunately these animals are found in several protected areas, such as the Udzungwa Mountains National Park or the Amani Nature Reserve, as well as several other forests reserves.
There is no specific conservation program focusing on the Tanzania Coast dwarf galago but the Zanzibar Forest Project, initiated to protect red colobus monkeys, has evolved over the years into a wider forest conservation program and should benefit this little prosimian as well as other species endemic to Zanzibar island.
- IUCN Red List
- Species-typical patterns of infant contact, sleeping site use and social cohesion among nocturnal primates in Africa – Simon Kenneth Bearder, Andrew Perkin, Elizabeth R. Pimley
- Taxonomy, Distribution and Conservation of Three Species of Dwarf Galagos (Galagoides) in Eastern Africa – Thomas M. Butynski, Yvonne A. de Jong, Andrew W. Perkin, Simon K. Bearder, Paul E. Honess
- Vocalization Analyses of Nocturnal Arboreal Mammals of the Taita Hills, Kenya – Hanna Rosti, Henry Pihlström, Simon Bearder, Petri Pellikka, Jouko Rikkinen
- www.inaturalist.ca – Galagoides-zanzibaricus
- Cryptic diversity and species boundaries within the Paragalago zanzibaricus species complex – Luca Pozzi, Anna Penna, Simon K Bearder, Johan Karlsson, Andrew Perkin, Todd R Disotell
- The Taita Mountain Dwarf Galago Galagoides Sp: A New Primae For Kenya — Andrew Perkin, Simon Bearder, Thomas M. Butynski, Bernard Agwanda, Benny Bytebier.
Written by Sylvie Abrams, November 2021