Changes in nearest-neighbor associations in a captive group of ...

274 McCann and Rothman
cepted their close proximity, although this was not systematically determined. These
findings are similar to those reported by Kirkevold and Lockard [1992] that show
silverback males rarely initiate contact with infants. Despite his lack of initiating
close proximity to the infants, M1 spent the most time (67.8%) near the infants compared
to any other female (19.2–37.8%), and the cluster most often included him
than any of the females. For the infants, it appeared that M1 provided protection and
a sense of security for them. Their closeness to him allowed them protection from
other group members’ more aggressive approaches. For example, whenever any of
the infants were distressed, usually due to the persistent approaches of the sub-adult
females, M1 would come to their aid and intervene in the encounter. This is in accordance
with data reported from wild populations of gorillas that showed that infants
are often attracted to the silverback because of his role as protector [Schaller, 1963;
Stewart and Harcourt, 1987]. As a result, the silverback can play a pivotal role in the
assimilation of infants into established groups [Fossey 1976, 1979; Van Elsackler et
al., 1990).
Infant Nearest-Neighbor Associations
The most significant result regarding the infants’ introduction into the group
was their strong dependence on each other for support and reassurance. For an overwhelming
amount of the time observed, another infant was the nearest neighbor of
each of the infants (Fig. 3), and when an infant was the nearest neighbor to another
infant, the distance was smaller compared to when that infant was nearest neighbor
to an adult. M1’s offspring (I1, I4, and I5) spent so little time with other adults
(