Observations on the ranging behaviour and daily activity of lone silverback mountain gorillas (Gorilla gorilla beringei)

It was tentatively concluded that availability of food supply regulated the silverback's movements and it was found that lone males did not move further nor more rapidly than groups.

Abstract

Two lone silverback mountain gorillas (Gorilla gorilla beringei) were followed during a 13-week study period in an attempt to describe the size and differential use of their respective home ranges. The ranging behaviour was compared to that of groups and possible causes of daily movement were examined. The daily activity of one individual is described. Considerable differences between silverbacks were found not only in the time spent within areas of their ranges but in the ways they ranged over their core areas. The subject that had left his parent group earlier covered his core area more vigorously, by means of circuitous routing. Lone silverback ranges overlapped their parent group ranges considerably and the group frequently entered the silverback's core area. Lone males did not move further nor more rapidly than groups. Feeding, social interactions, and location of nest sites were examined to reveal the possible causes of daily ranging behaviour and it was tentatively concluded that availability of food supply regulated the silverback's movements.