Proceedings of the First Symposium on Marsupials in New Zealand
Aspects of the Social Behaviour of the Possum Trichosurus Vulpecula
Seventy eight possums were individually marked and observed by dimmed spotlight in a pastoral habitat in Birdling's Valley on Banks Peninsula, New Zealand, between October 1972 and February 1974.
A distinct change occurred only in male behaviour at the beginning of the breeding season. Males made all the approaches during the breeding period. Females were initially antagonistic to males, but gradually became more tolerant. Promiscuity was not observed within a given breeding season and a short-term pair-bond was established. However, partners did change between breeding seasons.
Young first emerged from the pouch when about five months old but remained closely associated with their mothers until 8–9 months old. There was some evidence that young of both sexes dispersed when 11–12 months old.
Tracks were used communally and even the intensively used parts of both male and female ranges overlapped. It is possible that occupied den sites were defended and that an individual-distance system of spacing between animals, maintained by scent-marking, occurred. The type of social organisation found in possums is compared with that of other mammals.
CLOUT. Is there any evidence of a dominance hierarchy amongst the adult males in terms of mutually exclusive home-ranges?
JOLLY. We did not find this at Birdling's Valley. The only suggestion of any kind of dominance was in an adult female. However even she had a range which overlapped considerably with others in the autumn and she showed no sign of aggression to other animals there.
SUTTON. You said males follow the females at night. Are they responding to a scent secreted from some gland?
JOLLY. I am not sure, though their behaviour suggested they might be following a scent.
SUTTON. I wonder if it might be secreted during a threat posture?
JOLLY. It was not necessarily secreted during a threat display. Certainly the male followed nose-to-ground in situations where no threats were given.page 142
B.D. BELL. Have you any evidence that the repertoire of vocalisations varies between different possum populations. While I regularly heard the loud alarm or chatter call in Western Hutt, I have seldom noted it in the Orongorongo Valley forest.
JOLLY. I have only worked in the one study area so I cannot really comment on comparisons between different populations. The "kaa-kaa-kaa" chatter call you mention appears to be associated with a general alert situation, and it seemed to have some effect on other animals nearby. They would sit up on their haunches and look around and sometimes would even run up a tree.
WODZICKI. From your comments on behaviour it would seem to me that pherenomes may play a role - they have been shown to be important in our understanding of breeding behaviour and may have application in control work. I feel this is an area deserving more research attention as soon as practicable.
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