Loud Calls of the Yellow-Bellied Glider, Petaurus-Australis - Territorial Behavior by an Arboreal Marsupial

Abstract

The yellow-bellied glider, Petaurus australis, is possibly the most vocal of all marsupials but little attention has been given to the functional significance of its calling behaviour. This study describes various traits of the calling behaviour and examines their significance. The traits were: (i) calling occurred throughout the night but was more frequent in the first 3 h of activity; (ii) calling frequency was significantly greater near the boundary (9.1 calls per 30 min) rather than the core (2 calls per 30 min) of glider home ranges; (iii) calling and 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 were significantly higher after the playback (6.3 calls per 15 min) than before the playback (2.8 calls per 15 min). Gliders approached the area 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 seven functions proposed for loud calls of primates, indicates that the most likely function of calls is to mediate intergroup spacing. The traits of the calling behaviour, together with the observation that glider home ranges are virtually exclusive of those of neighbouring groups, suggest that calls serve a territorial function. The use of vocalisations appears to be the most effective method for advertising territories, 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 insufficient data to enable an adequate assessment of the function of loud calls among these species.