RODENTIA—RATS.
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).
Fig. 12.—The Black Rat.
Rutland records how, in 1856, the district of Collingwood, on the western side of Blind Bay, was visited by a swarm, and in 1863 he was informed of a swarm on the Shotover, Otago. I have heard of this one also. Old miners used to tell how they were nearly eaten out of provisions by an invasion of rats. Repeated swarms occurred in Picton in 1872, 1878, 1880, 1884, and 1888. Rutland says, “These rat-swarms invariably take place in spring. A few of the animals appear in August; they increase in numbers till November, when all disappear again gradually as they came. While in a locality dead rats are seen lying about in all directions—on roads, in gardens, and elsewhere. Very few have any marks of violence on their bodies; nor have they died of hunger, since, on examination, they are generally found fat. In 1884, in Picton, forty-seven dead rats were found lying together under the floor of the sitting-room in one house. In another thirty-seven were found dead under the kitchen. The whole town was pervaded with the odour of dead rats. The average weight of a full-grown specimen is about 2 oz. The fur on the upper portion of the body is dark brown, inclining to black; on the lower portion white or greyish-white. They run awkwardly and slowly on the ground, but run very quickly on the trees. When suddenly startled or pursued they cry out with fear. The extremely few females that occur amongst the countless hordes is a fact that shows that, if breeding does take place at all during these periods of travel, it must be on a very limited scale.”
I think a probable partial explanation of this problem is that only the males migrate, while the females, which are producing young at that very season—the beginning of spring—remain in their usual haunts.
“They do little damage, their food being green vegetables. Though they enter dwellinghouses and barns, it is evidently not in quest of food, as shown by corn and other eatables being left untouched by them.” Rutland adds, “Among English country people, who have the best opportunity of observing them, it is commonly asserted that in litters of young rats the males produced outnumbered the females by about seven to one.”
Meeson describes a plague of rats in 1884: “Nelson and Marlborough—in other words, the whole of the extreme northern portion of the South Island of New Zealand—is enduring a perfect invasion. Living rats are sneaking in every corner, scuttling across every path; their dead bodies in various stages of decay, and in many cases more or less mutilated, strew the roads, fields, and gardens, pollute the wells and streams in all directions. Whatever kills the animals does not succeed in materially diminishing their numbers. Young and succulent crops, as of wheat and peas, are so ravaged as to be unfit for and not worth the trouble of cutting and harvesting. A young farmer the other day killed with a stout stick two hundred in a couple of hours in his wheat-field.” Among reasons suggested for the visitation he suggests the pressure of famine: “Last summer was very wet, and last winter very cold; the amount of snow lying on the high lands in the interior was very great. Another is the excessive increase in numbers, producing an intense struggle for existence.” It is thus seen that his conclusions are somewhat different from those reached by Mr. Rutland, who did not think that hunger was an impelling cause. He goes on to say, “I have examined many of these animals, and have not found a single female. One of my neighbours has examined two hundred of them, and a Maori, at the pa beyond Wakapuaka, one hundred, with the same negative result. Some females have, however, been taken, and in one case they were found breeding. He is more like a big field-mouse than a Norway rat; and besides being considerably smaller he is slightly darker in colour, and less malodorous. He climbs trees and flax-plants, and is phytophagous rather than carnivorous.”
Hutton, writing in 1887, said, “The rat appears to have invaded Picton at the end of March, and to have suddenly disappeared by the 20th April. Old Maoris recognized it as the rat they used to eat in former times, and said that swarming on to the lowlands periodically was always characteristic of it. These rats were often noticed climbing trees. In the Pelorus, where they stopped longer, they built nests, like birds, in trees.”
Kingsley, in 1894, records it as nesting on the branches of small trees, 4 ft. to 5 ft. from the ground, near Totaranui, and gives examples from Motueka, Riwaka, Collingwood, Nelson, and Taranaki. I myself have seen tall thorn hedges at Whangarei full of their nests—large, shapeless structures, which at first I thought must have been made by house-sparrows which had taken to building in hedges.
At the present time black rats are extraordinarily common about Christchurch. Mr. Speight, the curator, informed me three years ago that Canterbury Museum was infested with them. A good deal of the damage said to be done to orchards by opossums is almost certainly the work of the black rat.
Marriner reports that he met with grey rats at North-west Bay in Campbell Island, which Waite, of the Canterbury Museum, thought were probably specimens of Mus rattus.
The brown, or Norway, rat (Mus decumanus) is ubiquitous, and, though there is no record of its arrival in New Zealand, it no doubt arrived here in the earliest days of settlement. Early in last century Russell, or Kororareka, in the Bay of Islands, was the chief port of the young colony, and rats must have become very abundant there. Charles Darwin, who visited the Bay of Islands in 1835, says in his account of the voyage of the “Beagle,” “It is said that the common Norway rat, in the short space of two years, annihilated in this north end of the Island the New Zealand species.” Dieffenbach, writing some time later, said he never could obtain a native rat, “owing to the extermination carried on against it by the European rat.” There is no doubt that this species has had a considerable share in the destruction of the native avifauna, and it is also responsible for much of the difficulty experienced by acclimatization societies and private individuals in their attempts to establish introduced game-birds, but I do not think it is responsible for the disappearance of the Maori rat.
Fig. 13.—The Brown or Norway Rat.
During visits to Stewart Island and the West Coast Sounds between 1874 and 1880 I was struck by the abundance of these animals in regions uninhabited and almost unvisited by man. One day I remember that the late Mr. Robert Paulin and I emerged from the bush on the south side of Thule, in Paterson Inlet, when the tide was low, exposing a wide stretch of beach nearly a mile long. We were much impressed by noticing that the whole beach was alive with large rats, which were feeding on the shell-fish and stranded animals which the tide had left exposed. As soon as they saw us they ran for the shelter of the bush; they were literally in hundreds. I am inclined to think that the rat which frequents all sheltered beaches on the coast is this common brown rat, and that it depends on the animal life of the sea-coast for its livelihood.
In 1868 H. H. Travers reported these brown rats as very abundant in the Chatham Islands; and Captain Bollons, of the “Hinemoa,” states that they are very numerous round the homestead on Campbell Island.
A few years ago, when a scare arose about the bubonic plague, a feeble and intermittent crusade against rats was inaugurated, especially in Auckland; but it was, as might have been expected, absolutely futile. It is, of course, well known that rats are the carriers of the plague germs, or at least that they harbour the fleas which are the real carriers. In the fifth and sixth chapters of I Samuel there is a very interesting account of the plague which attacked the cities of Philistia, and which produced emerods—that is, haemorrhoids or swollen glands—as a conspicuous symptom. The lords of the Philistines, in sending back the ark of God to the Israelites, because they thought it was the cause of the malady which affected them, accompanied it by models of emerods in gold, and also golden mice. These were probably golden rats, and seem to show that in these early days, three thousand years ago, the connection between the plague and the rats was well recognized.
While brown rats are still very abundant, especially about the towns, there is no doubt that the spread of weasels throughout the country has vastly diminished their numbers, especially in the open, for a weasel prefers a rat to a rabbit any day.
CHAPTER XIII.
RODENTIA—MICE AND GUINEA-PIGS.
The Mouse (Mus musculus).
It is probable that the mouse was introduced into New Zealand early in last century, yet the first notice of the appearance of this familiar little animal in the North Island is recorded by Dieffenbach, who wrote as late as 1839. Pastor Wohlers, long a missionary working among the Natives on Ruapuke, in Foveaux Strait, states that mice were first brought to that island in the “Elizabeth Henrietta,” which was wrecked there in 1824, and that even as late as 1873 they continued to be known as “henriettas.” The late Mr. Robert Gillies, who arrived in Otago in 1848, writing in 1872, says that it is quite certain there were no mice in Otago in 1852; but a year or perhaps two years after they were noticed, in Dunedin first. They quickly travelled south, but the Molyneux stopped their migration for a time, and it was considerably later before Molyneux Island (Inch-Clutha) was touched by them. Taylor White speaks of mice appearing in the Canterbury Plains in the early days of settlement (from 1855 onwards) “suddenly in thousands.” In 1866, during a discussion which arose at a meeting of the Canterbury Acclimatization Society as to the reported destruction of small birds by hawks, Mr. W. T. L. Travers reported “that he had opened a large number of hawks, and in all cases found their food to consist entirely of mice and grasshoppers.”
The mouse has never been found very far from the haunts of men, either in this country or elsewhere. It is abundant in all settled parts, and is also common on the Auckland, Antipodes, and Campbell Islands. Though it follows man so closely, it frequently stays in localities where men have been and have left, and there it is apt to have a bad time. Mr. Philpott, writing to me on the 2nd January, 1918, said, “There is a plague of mice in the district west of the Waiau. From Bluecliff to the Knife and Steel, near the Big River and beyond, each hut [the Government huts on the now abandoned telephone track to Puysegur Point] was overrun with them. And not only at the huts, but on the beach and in the dense bush, wherever we went, they were plentiful. At the Hump, near Lake Hauroto, they were as numerous as elsewhere. This prevalence of mice is certainly not usual; I have been on the Hump four or five times since 1911, and last year tramped along to the Knife and Steel, but, apart from an odd one or two, no mice were in evidence on former trips. One noticeable thing about these little creatures was their boldness: they were evidently very hungry. The wekas caught many of them, swallowing them whole, head first.”
How terrible a pest these rodents can be is shown by the state of affairs which has prevailed in the wheat-growing districts of Australia during the past season or two. The following note, taken from the Melbourne Age of the 17th July, 1917, gives some idea of the dimensions the pest has reached: “At Brooklyn there are nearly seven million bags of wheat, forming three and a half miles of stacks, and it is estimated that close on two million bags have yet to be railed thither from country stations. At Spotswood three million bags, most from the 1915–16 crop, are stacked.... The mouse plague in its myriads has attacked the Brooklyn stacks. The very air reeks with the smell of the mice, dead and alive. Daily to Brooklyn roll from seven hundred to eight hundred railway-trucks, loaded at the country stations mainly in the mouse-riddled areas of the Wimmera and the Mallee. From the Goulburn Valley the trucks bring with them, it is observed, mice that are few in comparison with those from the Wimmera and the Mallee. Every truck from these two regions contributes its mice to the swarming community at Brooklyn. And of the manner of the reception of these mice the instances afforded on an inspection on a week-day are at least suggestive. The average truck, when rolled alongside the wheat-stacks, is received by a handful of labourers. The bags are hauled up by tackle from truck to stack. When the last bag is lifted the doors of the truck are thrown open, and the chaff and the spoilt wheat broomed out. With the waste come flying out the mice—no great number in some trucks, but, clearly, on the average delivery of trucks a day, adding hundreds of mice to the pest, which has bitten deeply into the stacks at Brooklyn. Scattering, scampering, the mice race down the rails. A fox-terrier or two, wearing a blasé demeanour, condescend to catch a couple of mice as an example to the others. The rest of the new arrivals find shelter in the base of the wheat-stacks, or the low pile of damp, reeking bags of wheat awaiting reconditioning. Little if any effort seems to be made by the labourers to check the pest in an ordinary truck; and, indeed, a great deal of effort would be needed to be effective, and the reception and despatch of trucks must be inevitably delayed. Only when a badly infested truck, smeared with the flour of mouse-gnawn wheat, announces its contents by a vile reek of rotting mouse—an announcement beyond all risk of contradiction—it is detached, hauled off to another track, and left loaded to await special treatment.”
Two methods are adopted in Victoria to cope with the pest in the wheat-trains. One is to plug all the holes in the truck, place a sack in each corner with its mouth propped open with an iron hoop, and then proceed to lift the bags of wheat out of the truck on to the stack. The escaping mice jump into the sacks until they are nearly half-full. But if the mice are too numerous to be dealt with in this way, then they are gassed in the truck. I am not sure whether carbon disulphide or carbon dioxide is employed—probably the former. This takes at least an hour, and perhaps ten thousand mice are afterwards shovelled out of each truck; and, as hundreds of trucks full of wheat were arriving at Brooklyn each day, it is easily seen that the plague certainly was not stayed. What happens at Brooklyn has been happening in other parts of Australia, and we may be thankful that in New Zealand we have no such gigantic pests to cope with.
As the mouse breeds all the year round and produces five or six young at a birth, its rapid increase under favourable circumstances is easily understood.
The Guinea-pig (Cavia porcellus).
On the banks of the Rio de la Plata, and in the country lying to the northwards, a little animal, considered by many naturalists to be the wild form from which our domesticated guinea-pig is derived, is found in thousands. It is known as the “restless cavy.” It generally lives in moist situations, usually near the border of the forest, but never in the forest itself or in the open fields. Other authorities consider that the name “guinea-pig” is a corruption of Guiana-pig, and that the first specimens may have come from that part of America. The prevalent colours of the guinea-pig, as is well known, are white, black, and yellow, and in this respect it differs a good deal from the “restless cavy.”
It is hardly correct to include the guinea-pig among the wild animals of New Zealand, as, although it has been frequently liberated, it has never succeeded in establishing itself. At one time I had a number of guinea-pigs running wild in my garden in Maori Hill, and noticed that violets growing among the grass increased remarkably all the time they were about. The guinea-pigs kept the grass very closely nibbled, but would not touch the violets. These animals had a well-sheltered run under a thick mass of periwinkle which grew along a raised bank. They throve remarkably till a host of little ones, not much bigger than the end of one’s thumb, began to appear. This was too much for the cats in the neighbourhood. These creatures began to haunt the garden day and night. They soon ate all the little ones, and, having acquired a taste for this kind of game, they never stopped till they had destroyed all the stock but a few old bucks. There is no reason why guinea-pigs should not become wild in this country, except for the prevalence of cats.
The only record I find of the introduction of these animals into this country is by the Auckland Acclimatization Society in 1869; but they have been repeatedly brought in by dealers for the last fifty or sixty years. I believe that guinea-pigs are very good for food, for they are very dainty feeders. But there is a considerable prejudice against them on the part of most people. I had a bachelor acquaintance in London who used to give very recherché dinners to his male friends. On one occasion they got a dish of a new and very palatable kind, which they all enjoyed, until they learned that they had been eating guinea-pig, when some of them highly resented their host’s experimenting upon them. But it was only prejudice from which they suffered. They reminded me of the lady who enjoyed stewed eel until she learned what she had been eating, when she promptly retired from the table and managed to get sick.
The family of the cavies, to which the guinea-pig belongs, is chiefly characterized by the form of the teeth. The fore feet have four and the hind feet three toes, all armed with hoof-like nails. The tail is rudimentary or wanting; hence the common warning to children that if one lifts a guinea-pig by the tail the eyes will drop out.