UGANDAN CRESTED MANGABEY
Lophocebus albigena ugandae
Geographic Distribution and Habitat
The Ugandan Crested Mangabey is, as far as we know, Uganda’s only endemic primate. It occurs in a very fragmented population that has experienced drastic reduction in the last few years; this primate can be spotted from the northern shore of Lake Victoria to the west of the Nile River and from the forests of Tooro to the South Bunyoro regions of Western Uganda. In 2007, when the Ugandan crested mangabey received its distinction as a separate species, a study suggested that it occurred in six different sites, but a follow-up study in 2013 revealed that that number had been reduced to five. The Budzi Forest, known now as Kikonda, revealed a complete and total lack of Ugandan crested mangabeys perched in the treetops, mainly because there is also a noticeable lack of treetops; the forest has since been converted into farmlands and an exotic tree plantation.
Ugandan crested mangabeys inhabit low and medium altitude tropical rainforest. They are found in higher densities in the closed canopy forest and lower densities in the secondary forest.
Until 2007, the Ugandan crested mangabey was considered to be a subpopulation of the gray-cheeked mangabey (Lophocebus albigena). In 2007, the Ugandan crested mangabey and three other gray-cheeked mangabey subspecies were each recognized as distinct species because of sufficient differences between them. In the case of the Ugandan crested mangabey, Lophocebus ugandae, it was determined that their much smaller size and shorter skull were undeniably distinct from the other subspecies. However, taxonomy can sometimes be controversial. At a 2016 International Union for Conservation of Nature (IUCN) Red List assessment workshop, experts from the IUCN-SSC Primate Specialist Group were not in agreement about the four-species taxonomy. As a result, for the purposes of the Red List, they opted to retain a one-species listing with the gray-cheeked mangabey as the parent species and four-subspecies, one of which is the Ugandan crested mangabey, Lophocebus albigena ugandae.
Size, Weight, and Lifespan
Ugandan crested mangabeys are smaller than other mangabey species, but unfortunately there is no concrete quantitative data about their exact size or weight. We do know that they are not sexually dimorphic like other mangabey species, such as the rusty-mantled mangabey (Lophocebus albigena osmani), whose females have much larger teeth than the males.
The Ugandan crested mangabey has long, soft-looking, blackish-brown hair that covers their entire body, although it is noticeably lighter brown around their neck and shoulders. Their large ears are pressed close against their head and their long tails stand at a tall 90-degree angle when they move quadrupedally (on all fours). Their fingers are long, which is useful for grasping, and they have small, close-set almond eyes. Ugandan crested mangabeys look more similar to gray-cheeked mangabeys than they do to the other subspecies, although they do have a relatively large jaw structure in comparison.
Ugandan crested mangabeys are omnivorous with an obvious inclination towards fruit, which comprises about 59% of their diet. Some of their preferred foods include false nutmeg and breadfruit, the fruits of the date palm, and the fruits of the oil palm. Also on the menu for Ugandan crested mangabeys are young leaves, flowers, bark, pith, mushrooms, and invertebrates.
Occasional crop-raiding for maize, sweet potatoes, and groundnuts has been observed in Lwamunda and Mabira forests and is likely caused by forest degradation in those areas.
Behavior and Lifestyle
The Ugandan crested mangabey is diurnal (active during daylight hours) and mostly arboreal (tree-dwelling) and remains within the upper canopy of primary and secondary forests in order to forage. They will occasionally descend to the ground in order to move across larger gaps in forest cover or to snack on insects and mushrooms.
In Kibale forest, group sizes of Ugandan crested mangabeys have been reported to span anywhere from five to thirty individuals, but there are no data for any other Ugandan crested mangabey populations.
Much like the scant information about their size and weight, we also do not know much about their daily life and group dynamics, but we can surmise that they live life in a similar manner to the closely-related gray-cheeked mangabey.
Gray-cheeked mangabeys live in single male, multi-male, and multi-female groups. The males eventually depart from their natal group while the females do not. These mangabeys in general try to avoid other groups and thusly avoid antagonistic interactions with one another, which is helpful considering their territories can overlap.
Gray-cheeked mangabey females form a linear hierarchy below the alpha female, which determines the amount of food that a female is allowed to consume. The higher ranking females have access to the prime foraging spots and also enjoy the comfort and safety of foraging and eating peacefully in the middle of the group; lesser-ranked females are pushed to the periphery, where they must also keep an eye out for danger while they search for food, which inherently means they do not get to consume as much as the higher-ranked females.
Male gray-cheeked mangabeys also form a linear hierarchy that awards the higher-ranking males with greater breeding opportunities, though sneaky lesser-ranked males still take advantage of every opportunity they can get. Males often remain solitary until they find the right group.
Lastly, juvenile gray-cheeked mangabeys have been observed playing in the canopy and swinging from tree to tree.
Unfortunately, there is little to no data about the communication techniques of the Ugandan crested mangabey, so we will again defer to what is known about the closely related gray-cheeked mangabey until proper studies are completed on the Ugandan crested mangabey.
Mangabeys have a special throat sac that can produce loud calls; in males, the sac is larger and can produce a piercing alarm call that is utilized to warn others about a threat. Males also use barking calls and grunts to avoid those in other groups and a “whoop-gobble” call (which can be heard up to over half a mile (1 km) away) in order to get each others’ attention. Females make progression calls with short-range nasal grunts and will join in on some of the loud calls.
All mangabeys utilize visual communication when they come in contact with other mangabeys. They stare with an open mouth, teeth covered, as a threat display, which is usually accompanied by head-bobbing.
For tactile communication, mangabeys intertwine their tails in order to create strong social bonds.
Research is also required in regard to the reproductive habits and family life of the Ugandan crested mangabey, so we will again pull from the gray-cheeked mangabey. Their mating season starts in May and continues until September, although breeding can and does occur year-round. After a gestation period of six months, mothers give birth to a single infant. The infant is carried on its mother’s belly for a couple months, after which they switch to riding on her back. The infant is closely cared for by his or her mother for at least seven months (feeding, grooming, carrying) and generally looked after for the rest of the first year. Towards the end of its first year of life, the infant is groomed more by its aunts and siblings than its own mother. Males have been known to protectively carry infants as well.
Males are sexually mature at four to five years old and females get there at about four years.
Ugandan crested mangabeys act as seed dispersers due to their regular fruit consumption. Gray-cheeked mangabeys are known to spread pollen when they lick nectar from flowers and it attaches to their fur. This may be the case for Ugandan crested mangabeys as well.
Ugandan crested mangabeys are listed as Vulnerable (IUCN, 2018) by the International Union for Conservation of Nature and is appears on the IUCN’s Red List of Threatened Species. Their population size is unknown, but a suspected reduction of approximately 30 percent over the last 38 years is likely to have occurred due to forest degradation and habitat loss; that loss is probably permanent, irreversible, and still continuing today.
Many of the protected forests and reserves where the Ugandan crested mangabey live are not actually all that protected—they are susceptible to timber exploitation and forest conversion to exotic tree plantations and farmland. There is some reassurance that Ugandan crested mangabeys are sufficiently protected within Kibale National Park, but the largest remaining populations in Mabira, Bugoma Forest, Sango Bay Forest, and Minziro Forest reserve are dealing with habitat loss and degradation.
The IUCN states that the conservation actions needed for the Ugandan crested mangabey are the continued preservation of mature tropical high forest and the prevention of human-wildlife conflict due to occasional crop raiding. Kibale National Park is so well protected because there is a strong presence of law enforcement that has successfully discouraged timber exploitation and agricultural encroachment. In Mabira forest, efforts are currently under way to establish better protection for Ugandan crested mangabeys because of a partnership by the National Forestry Authority and NATURE AND LIVELIHOODS, a national NGO. Their aim is to promote the forest for eco-tourism and to experiment with buffer crops to reduce crop raiding and thereby eliminate conflict with humans.
The Mohamed bin Zayed Species Conservation Fund is attempting the strengthen the conservation efforts surrounding the Ugandan crested mangabey by habituating populations in Mabira for tourism purposes. By habituating the mangabeys to human presence, they can support both the local economy and conservation of the forest.
Written by Rachel Heim, December 2020