A. Vocal Communication.
1. Gorillas produce more than 15 recognized vocalizations. Some sounds are used mainly
for group communication because gorillas are nearly invisible to each other while feeding
and traveling in the vegetation. Deep belches are common during feeding and suggest
contentment. Primate researcher Dian Fossey, trained observers in the field to mimic this
sound when approaching feeding bands. Piglike grunts are used to establish right-of-way
during foraging and to settle squabbles.
2. Male gorillas roar and growl during aggressive behaviors (Dixson, 1981). Silverbacks vocalize the most.
3. Infants whine, cry, and chuckle.
B. Visual communication.
1. The ritualized charge display is unique to gorillas and includes demonstrative body
language. The entire sequence has nine steps: (1) hooting slow to fast, (2) symbolic
feeding, (3) rising bipedally, (4) throwing vegetation, (5) chest-beating with cupped
hands, (6) one leg kick, (7) sideways running, two-legged to four-legged, (8) slapping and
tearing vegetation, and (9) thumping the ground with palms to end display (Hoff and Maple,
1982).
2. Other aggressive behaviors are
stares, head jerks, lunges, grabbing, and biting.
3. Facial expressions for communicating include a play face, lip-tucking (tension), protruding tongue (uncertainty or concentration), and yawning (stress) (Dixson, 1981; Hoff and Maple, 1982).
Scientific Classification|Habitat and Distribution|Physical Characteristics and Special Adaptations|Senses|Behavior|Diet and Eating Habits|Reproduction|Birth and Care of Young|Communication|Longevity|Conservation
Issues|Bibliography|Specific Index
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