Introduction

Schaller (1963) and Fossey (1983) pioneered field study of gorillas, including study of the gorillas vocal communication (Schaller, 1963: ch. 5; Fossey, 1972). Their analyses were mostly of the males calls, indeed mostly of males loud, aggressive calls. We knownowthat gorillas give more or less benign within-group calls, close-calls, far more frequently than they roar, or scream, or bark (Harcourt et al., 1993). However, Fossey and Schaller were absolutely correct in identifying the long-calls and aggressive calls as frequent, and most often given by males – in the relatively unhabituated groups that they studied. Thanks to their lead, subsequent observers of gorillas could concentrate on the more subtle within-group behaviors, and do so with habituated groups.

Fossey and Schaller were both interested mainly in the social implications of the calling, the sociology of vocal communication. How did calls the behavior of other animals? Did they affect different animals differently? In this, they were unusual. Most analyses of non-vocal behaviors, grooming, proximity, aggression, had been sociological: how were the behaviors used to negotiate interactions, relationships, access to resources, and so on (Hinde, 1976, 1983). By contrast, the study of primates vocal communication has been far more concerned with its semantics, with discovering connections between the nature of a call and its referent in the environment, than with its social implications (Markl, 1985; Marler & Mitani, 1988). While broadcast communication has often been thoroughly analyzed, We knowmuch much less about that interesting realm of private – communication which is at the very heart of complex and highly organized animal societies (Markl, 1985: 174).