Some Soical Postures of Five Species of Rattus

Abstract

Adult male wild rats of the species Rattus norvegicus, R. rattus, R. villosissimus, R. fuscipes and R. lutreolus have been observed during encounters in large cages designed for observation and photography. In each encounter one male was a resident; the other an intruder of the same species. The postures and patterns of movement adopted during encounters are described and illustrated. Details of some interactions are given. Methods of maintenance are described. Behaviour patterns which are probably apotreptic (tend to cause withdrawal by a conspecific) include an arched back 'threat posture', and attack (leap occasionally accompanied by biting). Among probable epitreptic acts. (those that encourage approach or inhibit attack) are crawling under or over another rat. Allogrooming appears to be sometimes apotreptic, sometimes epitreptic. There is, however, little quantitative evidence on these apparent signals. A complete display, or pattern of social signals, probably includes sounds, odours, and tactile stimuli, as well as visible postures. Proposals are made on the names and classification of the postures. The actual or hypothetical roles of the various signals are reviewed.