primarily a leaf-eating species, ate more of the fruit as of the leaves of Celtis gomphophylla, a common
tree species in Budongo (see below).
Baboons
The Budongo Forest contains a large population of baboons of the species Papio anubis, the olive
baboon. Their density was found to be 11.7/km^2 (Plumptre and Reynolds 1994). They have been studied
primarily by Jim Paterson from the University of Calgary, and also by Adam Alberts Okecha from
Makerere University. They range deep inside the forest and subsist on forest foods. Those living in the
Sonso area are frequent visitors to the Sonso camp and the houses around the sawmill, where they eat
food waste thrown out by people and constitute a considerable nuisance by stealing human food.
Studies of baboons at the BFP include the following (for full details see References at end): Paterson
(1996, 1997a,b,c, 2001), Paterson and Teichroeb (2001), Paterson et al.(2001), Okecha (2000,
in press).
Blue monkeys
The first study of blue monkeys (Cercopithecus mitis stuhlmanni) in Budongo Forest was that of
Aldrich-Blake (1970), made in the Busingiro region. Aldrich-Blake described the ecology and
behaviour of the monkeys in that area, together with details of their social organization: he found that
they lived in one-male groups.
Today, blue monkeys are common in Budongo Forest when compared, for example, with Kibale Forest.
Their density in Budongo was found to be 43.9/km^2 (Plumptre and Reynolds 1994) and is higher in
selectively logged forest (58.2/km^2 ) than in unlogged forest (15.6/km^2 ). In a study of primate densities
before and after pitsawing, blue monkey densities were unchanged after the pitsawing ended (Beresford-
Stooke 1999).
Fairgrieve (1995a, 2003) studied the behaviour, ecology and social organization of blue monkeys in
great detail, and also made comparisons between blue monkey groups living in logged forest in the
Sonso area and unlogged forest in the Nature Reserve. He showed that they live at higher densities in
logged forest, their ranges are smaller in logged forest (see also Plumptre et al. 1997: 43; Plumptre, in
press), and there is a higher density of the kinds of foods they prefer in logged forest. Fairgrieve (1995b)
observed the takeover of one blue monkey group by an outsider adult male; the male fought and drove
out the resident male, after which he killed and ate an infant from the group he took over. There is fierce
antagonism between rival adult male group leaders. One male killed as a result of a fight between two
rival males (or possibly killed by a predator — the fight occurred after dark and could not be seen) had
the following characteristics when examined within 12 h of death (unpublished data): Length (tip of tail
to front of head) 62.5 in.; tail length 40.5 in.; body length 22 in.; front inside leg length 9 in.; rear inside
leg length 11 in.; hand length 4.5 in.; foot length 6.5 in.; weight 7.2 kg. This animal had cuts on the face,
both rear legs, one hand and a deep and severe wound in the belly which had punctured its stomach.
Fairgrieve (1997) describes how on 1 February 1994 he came across a group of excited blue monkeys
centred on an adult male who was holding and eating the carcass of a Lord Derby’s flying anomalure
(Anomalurus derbianus jacksonii) — a flying squirrel. The remains were examined and were still fresh,
indicating that the male had caught and killed it. Blue monkeys were also observed to eat guinea fowl
eggs during this study.
The fondness of blue monkeys for ripe fig fruits in particular but also for young fig leaves is described
in Tweheyo and Obua (2001).
260 Appendices