Blue monkeys are occasionally hunted and eaten by chimpanzees — see Chapter 3 of this book and
Newton-Fisher et al. (2002).
Studies of blue monkeys at the BFP include: Fairgrieve (1993, 1995a,b,c, 1997).
Redtail monkeys
Redtail monkeys (Cercopithecus ascanius schmidti) are the smallest of the forest monkeys in Budongo.
Their density in the forest as a whole is 33.3/km^2 , and as with blue monkeys they are found at higher
densities in selectively logged forest (46.4/km^2 ) than in unlogged forest (8.3/km^2 ) (Plumptre and
Reynolds 1994; Plumptre, in press). They are found in smaller, overlapping ranges in logged forest,
whereas in unlogged forest their ranges do not overlap (Plumptre et al. 1997: 44). Beresford-Stooke
(1999) in a ‘before and after pitsawing’ study found an increase in density of redtail monkeys after
pitsawing.
The ecology, behaviour and social organization of redtails were studied by Sheppard (2000). She
found that redtail densities were three times higher in selectively logged than in unlogged forest, and
that the selectively logged forest contained higher densities of preferred redtail food trees. As in the case
of blue monkeys, redtails live in one-male groups, with antagonism between male group leaders and
their rivals who live outside the group. Redtails and blues are often found together in mixed associa-
tions, and frequently alarm calls by one species are taken up by the other. Such mixed associations and
mutual alarm calling can also include the third forest monkey species, the black and white colobus.
As in the case of blue monkeys, redtails are fond of ripe fig fruits and also young fig leaves (Tweheyo
and Obua 2001).
An unusual form of interaction involving a redtail monkey was recorded by Tinka and Reynolds
(1997). On 4 September 1996, Gonza, then a subadult female chimpanzee, initiated play with an adult
redtail monkey. At 8.47 a.m. ‘she played with the tail folding it around her neck’, shook it, and groomed
the body of the redtail. ‘The monkey stretched its legs to allow easy reach for Gonza. She groomed it
under the abdomen, chest and back. The grooming was mixed with playing e.g. beating the sides of the
monkey, pulling its legs, and Gonza rubbed her vagina against the anus of the monkey. The whole
process lasted 20 minutes...Gonza was the actor only...At 9.07 the monkey terminated this activity
by moving away’ (p. 6).
Studies of redtail monkeys at the BFP include: Sheppard (2000), Sheppard and Paterson (2001a,b).
Black and white colobus monkeys
Black and white colobus monkeys (Colobus guereza) with their flowing black and white robes are
spectacular primates as they move in the canopy. As with the redtails and blues, they are plentiful in
Budongo. Their density is 39.3/km^2 for the whole forest, and as with the blues and redtails they are
more numerous in selectively logged forest (44.2/km^2 ) than in unlogged forest (27.0/km^2 ) (Plumptre
and Reynolds 1994). Beresford-Stooke (1999) in her ‘before and after pitsawing’ study referred to
above found an increase in density of black and white colobus monkeys after pitsawing.
Whereas colobus monkeys are often characterized as leaf-eaters, in contrast to the cercopithecine
fruit-eaters, in Budongo Forest this opposition breaks down. A close comparison of diets of the
three forest monkey species showed that more fruit than leaves was eaten by colobus. This is in contrast
with the situation in Kibale Forest and at other sites. One of the major items in the diet of black and
white colobus monkeys at Budongo was the fruit of Celtis gomphophylla (previously durandii)
Other primate species of the Budongo Forest 261