Sympatric populations of lowland gorillas (Gorilla
gorilla gorilla) and chimpanzees (Pan troglodytes
troglodytes) in the Lopé Reserve in central Gabon
consumed insects at similar average frequencies over a
7-year period (30% versus 31% feces contained insect
remains). Data came mostly from fecal analysis
supplemented by observation and trail evidence. The
weaver ant (Oecophylla longinoda) was the species eaten
most frequently by both gorillas and chimpanzees. Other
species of insects wore eaten but there was virtually
no overlap: Chimpanzees used tools to eat Apis bees
(and their honey) and two large species of ants;
gorillas ate three species of small ants. Thus, despite
their shared habitat, the esources utilized were not
identical as gorillas do not show the tool-use
technology of chimpanzees. The frequency of
insect-eating by both species of ape varied seasonally
and between years but in different ways. This variation
did not seem to be related to the ratio of fruit to
foliage in their diets. Gorillas of all age-classes ate
insects at similar rates. Comparisons with insectivory
by other populations of gorillas indicate differences
exist. Mountain gorillas (Gorilla g. beringei) in the
Virunga Volcanoes, Rwanda, consume thousands of
invertebrates daily, eating them inadvertently with
handfuls of herbaceous foods but they deliberately
ingest insect-foods only rarely. Lowland gorillas at
Lopé habitually ate social insects, and their selective
processing of herbaceous foods probably minimizes
inadvertent consumption of other invertebrates.
Gorillas at Belinga in northeastern Gabon, 250 km from
Lop6, ate social insects at similar rates but ignored
weaver ants in favor of Cubitermes sulcifrons, a small
species of termite that occurs at Lopé but was not
eaten by gorillas. This indicates that local traditions
similar to those reported for chimpanzees also exist
amongst populations of gorillas.

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