Seven species of rodents have been introduced into this country at one time or another. Of these, three species of rat, the mouse, and the guinea-pig belong to the simple-toothed rodents--that is, they never have at any period of their life more than two incisors in the upper jaw. The rabbit and the hare belong to the double-toothed rodents. These have each two large incisors in the upper jaw, and behind them two small--almost rudimentary--incisors.
A species of rat was one of the four land-mammals occurring in these islands when Captain Cook first visited New Zealand, the others being a dog and two species of bats. Sir Joseph Banks says in his Journal, “On every occasion when we landed in this country we have seen, I had almost said, no quadrupeds originally natives of it. Dogs and rats, indeed, there are--the former, as in other countries, companions of men, and the latter probably brought hither by the men. Especially as they are so scarce that I myself have not had an opportunity of seeing even one.”
This was not Forster’s experience, for in his account of the second voyage of Cook (in 1773) he says, “Our fellow-voyagers [Furneaux in the ‘Adventure’] found immense numbers of rats upon the Hippah Rock [Queen Charlotte Sound], so that they were obliged to put some large jars in the ground level with the surface, into which these vermin fell during the night by running backwards and forwards, and great numbers of them were caught in this manner.” It is now almost certain that this native rat was the same species (_Mus exulans_) as is still common in many of the South Sea islands and throughout the Pacific, and it probably came with the original immigrants, the ancestors of the Morioris and Maoris. It is, however, probable that the common European black rat (_Mus rattus_) came also into the country with the various ships which touched at these shores from 1769 onwards. Indeed, Yates, who wrote in 1835, says, “The Natives tell us that rats were introduced in the first ship by Tasman.” He is certainly not an authority on the subject, and too much importance need not be attached to his statement; but it is nevertheless interesting. In Cassell’s Natural History, Dallas, who writes on the Rodentia, says, “New Zealand at the time of its discovery harboured a rat known as the forest-rat, or Maori rat, which was a favourite article of food with the Natives, and is now almost extinct. It has been proved by Captain Hutton to be identical with our black rat (_Mus rattus_), and was probably introduced by the ancestors of the Maoris.”