Nocturnal behaviour of the parma wallaby, Macropus parma (Marsupialia : Macropodoidea)

Abstract

Commercial night-vision devices permit the study of nocturnal behaviour without visible light sources, obviating concerns about the effects of supplemental lighting on natural behaviour. We used an inexpensive image intensifier to document the previously unstudied nocturnal behaviour of the parma wallaby, Macropus parma Waterhouse, 1846, based on a captive population of 6 male and 6 female sexually mature wallabies. A total of 150 h of observation was conducted over 34 nights and 6 days. The circadian rhythm of this species was grossly similar to that of many other Macropodoidea, although there was a pronounced peak in activity at dawn. The behavioural time budgets of males and females were reliably different, with males spending more time actively foraging than females. Social interactions were rare in both sexes, but we were able to characterise sexual behaviour in detail. Courtship typically began with sexual checking of the female by the male, after which the male pawed the female’s rump repeatedly. This was occasionally followed by mounting and copulation, but typically the male presented his chest, drawing the female’s head toward it with his forepaws. While this ‘head rubbing’ is clearly homologous with components of social behaviour in other wallabies, it seems uniquely elaborate in parmas. Interactions between males and females were accompanied by characteristic vocalisations. Males produced repeated broad-band ‘clucking’ sounds while grooming females, who often responded by hissing. The structure and context of these signals suggest that clucks function to stimulate the female, while hisses probably encode threat. It is likely that males produce both olfactory and acoustic signals during courtship; such cues could play a role in mate choice decisions by females. Our results demonstrate that nocturnal observations on small macropodids are feasible and suggest that more reliable information about social behaviour is obtained at night.