The gnawing-animals, which constitute the order Rodentia, form the most sharply defined group of the Mammalia, the distinguishing characters and name being derived from their teeth. These are of two kinds only—viz., incisors and grinders—there being two efficient incisors in each jaw, and from three to six molars. There are no canine teeth at all; consequently it is easy to recognize the skull of a rodent by its dentition. The animals are mostly small, the beaver being about the largest; while some kinds of mice are hardly more than a couple of inches long.

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.”

I do not know when this was written, for Messrs. Cassell and Co. take the precaution not to put dates on many of their books. But Hutton, in vol. 20 of the “Transactions of the New Zealand Institute” (1888), speaks of the rats which invaded Picton and the Marlborough Sounds as Mus maorium, and says, “This rat is certainly different from Mus huegeli, from Fiji, and, I should think, from M. exulans.” The whole subject has recently been investigated by Oldfield Thomas, who is the greatest living authority in this group, and he is certainly of opinion that the kiore, or Maori rat, was the common Pacific species, M. exulans. Endless confusion occurs, however, among early writers in speaking of rats and their species, and this must be borne in mind in reading the accounts of these animals.

The Rev. R. Taylor—who is not always, however, a reliable authority—says that this Maori rat was in general size about one-third that of the brown, or Norway, rat. The Maoris used to make elaborate preparations to catch them, and hundreds of them would be captured at one hunting. He says the animal is reported to run only in a straight line, and that the Maoris made special lines of roads in order to lead them into their traps, which were baited with miro and other berries. If these roads were crooked, they said, the rats ran into the forest at the bends. They fed entirely on vegetable matter, and were greatly prized as food by the Natives, who also extracted much oil from them.

The native rat quickly disappeared before other rats and also cats; it was extremely rare thirty or forty years ago, and is probably quite extinct now. As, however, the species is common in Polynesia, occasional immigrants may arrive in New Zealand from time to time. The popular belief among both Maoris and Europeans was that it was exterminated by the Norway rat (Mus decumanus). It is, however, probable that the latter is a more recent immigrant than the old European black rat, which is still an extremely common animal here. That the Maori rat was once very abundant seems to be proved by the fact that the Natives always erected their storehouses for food on various kinds of piles as a protection against the depredations of these animals. This habit, according to Judge Mailing (“Pakeha Maori”), was the custom before Europeans landed in the country.

Tancred, writing of Canterbury in 1856, says, “The native rat forms numerous burrows, rendering the soil unsafe for a horse.” He also repeats the statement about its being exterminated by that formidable invader the Norway rat. Mr. W. T. L. Travers, writing in 1869, says, “It has been the fashion to assume that before the arrival of Europeans in this colony this creature [the native rat] was common, and to attribute its destruction to the European rat; and, indeed, the Natives have been credited with a proverb in relation to this point. It is not in effect impossible that the ultimate destruction of those which still existed when trade was first opened between Europeans and the Natives, long after the colonization of New Zealand, may have been hastened by the introduction of the European rat; but I am satisfied that before that time they had become very scarce, and, indeed, I have been told by gentlemen who have lived in the northern part of this [the South] Island for upwards of forty years that they never saw a specimen.”

Speaking of Nelson in 1842, Judge Broad said, “Native rats were an intolerable nuisance; they ate everything, ran about the houses in the dark, and had no fear of man. They drove the cats away, and only disappeared when rat-killing dogs were introduced.” I do not think these were native rats at all, for the latter ate only vegetable matter, and these vermin seemed to eat everything.

Dr. Hocken has an interesting statement in his “Early History of New Zealand,” as follows: “In 1840 Messrs. Dodds and Davis, of Sydney, established a farming settlement at Riccarton, close to where Christchurch now stands, and sent down James Heriot (or Hariot) as manager, two farm hands, and two teams of bullocks. They ploughed and cultivated about 30 acres of land and secured their crops. But in less than a year they decided to abandon all further efforts. Numberless rats attacked the garnered stores, and the bar at the mouth of the river or estuary proved a sad obstacle to shipping whatever grain had been spared by the scourge of rats.” We do not know now which species this was, though I think it was probably the black rat.

It is rather interesting that in 1870 Sir Walter Buller wrote a paper “On the New Zealand Rat,” and he both figured and described the European black rat (Mus rattus). I have already said that this rat probably arrived with some of the first ships which came to the country. Oldfield Thomas in a paper written in 1897 in the “Proceedings of the Zoological Society” says that the rats normally inhabiting ships are not, as is commonly supposed, Mus decumanus, but Mus rattus, and in most cases these are of the grey variety of that animal, with white belly, though the black form may often be caught in the same ship as the grey.

The black rat became enormously abundant in the early days of settlement, and moved about the country in vast armies. The settlers, bushfellers, and sawmill hands of fifty or seventy years ago recorded how invasions of them in countless swarms used to move through their district, climbing everywhere, and eating everything before them that was of a vegetable nature. Oldfield Thomas, in the article already referred to, says, “All the world over Mus rattus takes to roofs and trees on meeting its formidable rival, Mus decumanus, to which it leaves the gutters and cellars.”

In early days in Southland we often heard about rat invasions, and the popular belief then was that these were migrations of native rats. I think there is little doubt that they were black rats, which are not necessarily black-coloured. I propose to quote now from various writers on the subject, to show how common these rodents were at times.

Taylor White states that on the west coast of the South Island they came in vast crowds, climbed trees, tent poles and ropes, and ate everything. On the shores of Lake Wakatipu they lived under the dead leaves of the wild-spaniard or spear-grass (Aciphylla squarrosa and A. Colensoi).