Opossum Pastoral Grazer

Press, Volume CIV, Issue 30835, 21 August 1965, Page 10

Opossum Pastoral Grazer

FEW realise that in many areas the opossum is as much a pastoral grazer as a tree browser, consuming food that would otherwise be eaten by stock, says Mr D. J. P. Gilmore, of the zoology department of the University of Canterbury, in an article quoted by the latest newsletter of the Rabbit Destruction Council.

Though it had previously been considered that opossums did not take grass in any quantity, examination of the food eaten by these animals on Banks Peninsula showed that this was not so. Pastoral grazing was carried on throughout the year. It occurred when other foods were plentiful and was therefore not just the result of over-population and consequent food shortage.

Opossums collected at Waimangaroa, in the Buller re-

gion, at Cust, in North Canterbury, and in the hill country near Kaikoura had also been found to consume large quantities of grass and clover, confirming what had already been observed on Banks Peninsula.

A large opossum (weighing 7 to 81b) would eat up to 11b of food in a night. Opossums kept in captivity and fed only on grasses and clover lost some weight, but had been kept for more than a fortnight on these plants alone. Selective feeding was probably carried on under natural conditions and opossums might quite seriously reduce the carrying capacity of the land by selecting only the best grasses and clovers.

The actual damage caused by the opossum in pastoral land could not, however, yet be fully ascertained, mainly because there had been little

scientific investigation into this subject. Mr Gilmore said that on many parts of Banks Peninsula where root crops were grown as winter feed for sheep and cattle opossums would travel long distances to feed on them and many well defined tracks, often through long stretches of grass, were made by opossums travelling from the bush and gorse to the paddocks. Swede, turnip and chou moellier had been found in the stomachs of many of the opossums examined. At present large sums of money were being spent on control and .none of it was being directly recovered, Mr Gilmore said. This appeared to be unfortunate when some of the expenditure could be recovered from the sale of skins and by fostering a market for the carcases as pet meat.