Chimpanzees of the Budongo Forest : Ecology, Behaviour, and Conservation

64 Diet and culture at Sonso

These results were statistically significant and showed that, for fruits, flowers and
leaves on the same tree, fruits of the same species, and fruits of different species, there
were two rules:

1. Chimpanzees chose to eat foods with a higher sugar content in preference to fruits
   with a lower sugar content.


2. Chimpanzees chose foods irrespective of the level of condensed tannins.

The sugar finding was entirely as expected; but we had no explanation for the tannin
finding except to conclude that chimpanzees have a much greater tolerance of condensed
tannins that humans do. Human children are highly sensitive to tannins at first, but if they
encounter them in the diet regularly their sensitivity wears off and they develop an improved

bpy ka fsa cya fn cls

fsu fe cdu

Species (trees only)

fb uc com

0

10

20

Mean condensed tannins (mg/g)

30

bpy ka fsa cya fn cls

fsu fe cdu

Species (trees only)

fb uc com

0

20

40

60

80

100

120

Mean total sugars (mg/g)

(a) (b) 140

Whether eaten or not

Ye s N o

Fig. 4.3: (a) Condensed tannin content found in foods eaten and not eaten. (b) Total sugar content
found in foods eaten and not eaten (from Reynolds et al. 1998).
BpyBroussonetia papyrifera,fsuFicus sur,kaKhaya anthotheca,feFicus exasperata,
fsaFicus sansibarica,cduCeltis durandii,cyaCynometra alexandri,fbFicus barteri,
fnFicus natalensis,ucUvariopsis congensis,clsCaloncoba schweinfurthii,
comCordia millennii. Species are shown in order of preference from left to right.

Table 4.4: Sugar and condensed tannin levels found in foods eaten and not eaten

(from Reynolds et al. 1998).

Item Mean Mean SD tP

eaten not eaten

(n209) (n19)

Tannins 15.54 12.37 11.28 0.33 n.s.

Sucrose 13.64 14.11 22.33 0.28 n.s.

Fructose 23.63 8.84 25.50 3.41 0.002

Glucose 28.73 8.47 26.67 3.44 0.002

Total sugars 68.01 31.42 54.79 2.81 0.009