Historical Background of Trichosurus Vulpecula in New Zealand

Trichosurus vulpecula was initially introduced into New Zealand from the Australian mainland and Tasmania in the mid-nineteenth century, but did not become established successfully until about the end of the century. Thomson (1922), quoting F. Hart of Southland, wrote that the food of the possum was chiefly seeds of broadleaf, kamahi, panax, maple (Pittosporum), fuchsia, and makomako, rata blossoms and supplejack berries, and practically all seeds page 43 that grew in the bush. The possum was not considered to be a grass-eating species, though it would eat red and white clover and sweet-briar shoots. The damage that the animals could do when running at large was thought by Thomson to be very little, seeing that they never came out into open country.

Perham (1924) said that in a search for damage by possums that might be construed as materially affecting the forest, results had not been very fruitful - in fact only one instance of extensive bark-biting had been found. Perham considered that their leaf-eating habit, if moderate (as had been the case up until then), would have no bearing on the welfare of the forest "as trees have been subjected to and withstood such from pigeons through many centuries". Where death of one or two specimens of some tree species (e.g. northern rata Metrosideros robusta) was evident, the theory was that the tree had reached its allotted span and was dying away. Other similar examples were quoted.

Cockayne (1928) thought that if the possum was doing noticeable damage, the forests would unmistakeably point to this in their dead trees. But the forest, according to Cockayne, was untouched by damage from possums: "If damage of any kind there be, it is so slight as to be negligible". Nor did he consider that the animals affected the all-important floor covering or reduced the seed crop to any great extent. "At any rate, if it is proved eventually, which is most unlikely, that opossums are a menace to forests, their skins are so valuable that at any time the animals can be reduced in numbers to the extent desired without any cost. Unlike deer, it would pay handsomely to keep the opossum under strict control".

However, Kirk and Bendall (1919) were much more concerned about the possums' effect on Kapiti Island. Damage to kohekohe Dysoxylum spectabile, mahoe Melicytus ramiflorus, passion-flower Tetrapathaea tetrandra, and fuchsia Fuchsia excorticata was noticeable, and these authors thought that the only safe aim was the absolute extinction of the possum on Kapiti Island.