LOUD CALLS OF THE YELLOW-BELLIED GLIDER, PETAURUS-AUSTRALIS - TERRITORIAL BEHAVIOR BY AN ARBOREAL MARSUPIAL

The yellow-bellied glider, Petaurus australis, is possibly the most vo cal of all marsupials but little attention has been given to the funct ional significance of its calling behaviour. This study describes vari ous traits of the calling behaviour and examines their significance. T he traits were: (i) calling occurred throughout the night but was more frequent in the first 3 h of activity; (ii) calling frequency was sig nificantly greater near the boundary (9.1 calls per 30 min) rather tha n the core (2 calls per 30 min) of glider home ranges; (iii) calling a nd gliding were highly correlated; (iv) calling rate was influenced by a glider's feeding behaviour; and (v) experimental playback of calls (simulating an intruder) resulted in calling rates by gliders that wer e significantly higher after the playback (6.3 calls per 15 min) than before the playback (2.8 calls per 15 min). Gliders approached the are a of playback in 50% of tests; in one instance from a distance of 200 m. Assessment of the calling behaviour of gliders, by reference to sev en functions proposed for loud calls of primates, indicates that the m ost likely function of calls is to mediate intergroup spacing. The tra its of the calling behaviour, together with the observation that glide r home ranges are virtually exclusive of those of neighbouring groups, suggest that calls serve a territorial function. The use of vocalisat ions appears to be the most effective method for advertising territori es, which commonly exceed 50 ha. A review of the use of loud calls by other species of arboreal marsupial showed that at present there are i nsufficient data to enable an adequate assessment of the function of l oud calls among these species.