(Plumptreet al. 1994: 71; Plumptre, in press). The five commonest items in the diet of C. guerezaat
Budongo were:
- Celtis gomphophylla— ripe fruit — 16.65% of diet
- Celtis gomphophylla— unripe fruit — 14.61%
- Celtis gomphophylla— mature leaves — 6.90%
- Cynometra alexandrii— young leaves — 6.52%
- Cynometra alexandrii— seeds — 5.51%
We therefore have fruit-eating colobus monkeys at Budongo.
Preece (2001, in press) studied the density of black and white colobus monkeys in Budongo Forest in
relation to the abundance of lianas. Past studies, e.g. at Kibale Forest, have shown a higher density of
black and white colobus monkeys in logged areas and a partial explanation for this has been sought in
the abundance of lianas with mature leaves in disturbed forest. Preece examined whether this source of
leaves was an important food source for the colobus monkeys of Budongo Forest. Lianas, with a dia-
meter of 1 cm or greater, were counted in a number of sample plots, and correlated with the density of
Colobus guerezain the areas concerned. He found that whereas abundance of lianas did not correlate
with density of colobus across compartments (large areas of forest), within compartments there was a
good correlation. He concluded that the effect of liana abundance on colobus density is masked across
large areas by confounding variables such as habitat type, but that within smaller areas, forest lianas,
especially the larger ones that provide large quantities of leaves in the canopy, are an important food
source of C. guerezain Budongo and do in part determine density. He found a greater abundance of
lianas in logged forest than in unlogged forest, due to the creation of gaps by logging activities and
agreed that this could help to explain the higher densities of colobus found in logged forest than
in unlogged. However, we need to recall that Budongo colobus are mainly fruit-eaters and so liana
abundance can provide only a supplementary explanation, the main one being (as for the other forest
monkeys) the increased abundance of edible fruiting trees in the logged forest.
The detailed ecology, behaviour and social organization of black and white colobus monkeys in
Budongo Forest remains to be studied. This is an interesting species and its characteristic loud, low-
pitched gurgling sound is one of the delights of Budongo. Every morning, at around 7 a.m., all of
the colobus groups around camp join in a 5-min morning chorus which is one of the most enjoyable
sounds of the forest and a very pleasant way to start the day. I suspect it is the dominant males
that call. I do not think these colobus monkeys live in one-male groups; more likely they live in
multi-male groups. This may in part be because of the protection this affords from predators,
notably chimpanzees.
Chimpanzees in Budongo Forest are not great hunters but the majority of monkey prey are colobus
(Newton-Fisher et al. 2002). Young individuals are preferred. Colobus-eating has been described in
Chapter 3. I end with a small tribute to the colobus: on one occasion, the day after we had found the
hairs and some bones of a young colobus monkey in the faeces of one of our adult male chimpanzees,
we encountered this individual, together with three other adult male chimpanzees, in a food tree with
two adult male colobus monkeys. They appeared to be sparring — the colobus were rushing towards the
chimpanzees and the chimpanzees were responding in a similar way. After a while the two colobus
males made a joint concerted rush at one of the four chimpanzees which backed down and fled, with the
262 Appendices