The agonistic vocalisations of Rattus villosissimus

Abstract

All sounds produced by R. villosissimus during agonistic behaviour were recorded for spectrographic analysis. The social context of sound production was noted, along with any immediate overt changes in the behaviour of recipient rats. The effect of sounds on an opponent was also tested by playing prerecorded sounds to individual rats and observing their behaviour. R. villosissimus possess a large vocal repertoire. They produce five basic sounds in the audible range: squeal; squeak; tooth chattering; hissing; coughing. Squeals consist of a whole range of graded intermediates, allowing a great potential for communication. Most sounds appear to have little immediate overt effect on the behaviour of opponents. Suggestions are made as to their significance in communication.