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Proceedings of the First Symposium on Marsupials in New Zealand

Some Contrasts Between Populations of the Possum Trichosurus Vulpecula in Different Aged Stands of Pinus Radiata

page 143

Some Contrasts Between Populations of the Possum Trichosurus Vulpecula in Different Aged Stands of Pinus Radiata

* Present address: Ecology Division, DSIR, Private Bag, Nelson.


Possums were studied by live-trapping and poisoning in young (2–4 year old) and middle-aged (13–15 year old) plantations of Pinus radiata near Tokoroa. In the latter area animals grew to a larger size and some females produced two young a year, contrasting with the single breeding season in young stands. These differences are discussed in relation to the winter foods available in the two habitats.

General Discussion

KEBER. I am not sure what you attribute the difference in the size of possums between your areas to. I found there was an increase in size with altitude and I notice this happens in Kaingaroa.

CLOUT. Well, if anything, it would be the reverse trend in my two areas for the younger stands of trees had the smaller animals but were at a slightly higher altitude.

KEBER. In your case one area is a cut-over tawa Beilschmedia tawa forest and the other is one that has been in P. radiata for some years. In Kaingaroa both areas were second rotation P. radiata.

CLOUT. So you are implying differences in habitat quality?


FITZGERALD. Do you know if there was any difference in the rainfall between the two areas?

CLOUT. It would have been higher on the Mamaku Plateau in the younger trees.

COLEMAN. You mentioned females producing two young a year and in an earlier paper J. Jolly mentioned that young were dependent on the mother for about 8 months. This suggests such females must be suckling two young. Also I think males have been found in greater numbers than females in the- pouch-young in any population studied in this country at least. This would support your findings.

CLOUT. I think the excess of males in my younger pine stand was due to greater dispersal of young males into the area rather than to a greater number of males born there. There seems to be a difference in dispersal patterns between the sexes during their immature phase, when about one year old or less.

page 144

COLEMAN. Regarding fat estimations, you no doubt know that Dr Bamford in his paper* applied regression constants but these only referred to Westland populations.

CLOUT. Yes, I got different regression constants worked out from my own data.

* BAMFORD, J. 1970. Estimating fat reserves in the brush-tailed possum, Trichosurus vulpecula Kerr (Marsupialia: Phalangeridae). Australian Journal of Zoology 18: 415–425.