Art. XXIII.—On Rats and Mice.
[Read before the Hawke's Bay Philosophical Institute, 11th November, 1890.]
Owing to my pastoral occupation I have mostly lived on the outskirts of civilisation, residing in districts formerly little known and sparsely populated. This was eminently favourable for the observation of the indigenous fauna, and of the gradual spread of imported animals. In this paper I will endeavour to set before you my experience on the subject of rats and mice.
Coming to the Province of Canterbury at the commencement of the year 1855, I at once went into what is now known as the Oxford district, and assisted in starting the Warren Station. We had shipped a brace of pointers to use on shooting-excursions after the New Zealand quail; but even in those early days quail were becoming very scarce in that part of the country—possibly owing to burning off the native grasses to cause green feed to spring. Having no game to work the pointers to, they were utilised in hunting minor game—rats, for instance. We would take a spade, and walk out on the plains, which were like a great sea, whose limit was the horizon, or, on the west, the apparently endless ranges of mountains,
clothed at their base with dark-coloured evergreen forest, while above the timber-line were Veronicas and areas of yellow-brown covered with tall snow-grass, tangled together by thick masses of their former growth, bending downward, dead and grey, never having been burnt by the Maoris for centuries probably; crowned with grey peaks where the jagged rocks and their broken fragments pointed to the sky. These ranges were then considered an “Ultima Thule.” Looking far away to the east were the dark rough outlines of the Port Hills, and near by Burnt Hill, standing alone like an island surrounded by an endless sea of yellow tussock (Poa australis). On favourable occasions a wonderful mirage would be seen, when the silver line of the waters of the Waimakariri would be distinctly seen pictured above the edge of the horizon, a glistening, winding, silver band with its fringe of small kowhai-trees clearly defined. In looking for my flock of sheep I have seen them like rows of trees, when, in reality, they were hidden in lower ground some two miles away, and were not to be seen looking from half the distance with the aid of a telescope. A telescope was an essential part of a shepherd's outfit in those days. On the occurrence of a mirage the day would be hot, and the evaporation, when closely noticed, could be seen ascending with a quivering, tremulous motion some 6ft. upwards from the heated ground. Taking a spade and the pointers, we would beat around, and the dogs would presently come to a stand. Going up, an area of some 10ft. would be noticed of a nice bright-green colour among the prevailing brown, being free from tussock, and covered by a small flattish-leaved grass, whose leaves had their points curved or bent towards the ground. At distances apart in this green patch were numerous rat-holes. We would commence to dig, and the dogs stood ready to field the rats—of which there was generally quite a small community—as they bolted. One day a laughable scene occurred: a dog had just nabbed a rat, when another rushed out. Bravo opened his mouth automatically, as it were, and the rat, in his hurry, jumped straight in. The dog then, with two rats hidden in his capacious mouth, looked round in a dazed and helpless manner, as if asking advice what to do under these strange conditions. At other times a rat would spring at a dog, and hang to its nose or pendulous upper lip like a veritable bulldog.
This same green grass, I think, was similar to a kind seen since in Hawke's Bay. If so, it has a large seed, which might have been collected as food and stored by the rats, some of which being dropped would grow around their dwellings. Yet I do not remember finding any stored, but only nests of dry grass. Or the ground being manured and made fertile by
the rats may have induced this particular grass to grow and establish itself.
I did not at that time consider these rats as anything out of the way, being fully prepared to find things upside down at the Antipodes. From recollection, they were reddish-brown, and perhaps white underneath, of a fair size, and not unlike the Norway Rat (Mus decumanus). Still I feel certain they could not be the Norway rat, but a distinct species of a more social disposition, for full-grown ones lived together to the number of eight to fourteen, and were not a family of young rats. The tradition at that time among the Canterbury settlers was that the Maori rat was of a red colour. I never remember any one noticing these rat-warrens or speaking of their occupants as the Maori rat. To show how little likely unscientific persons are to notice small peculiarities in rats, I may say that as a boy I was constantly killing rats in England adjoining a large piece of water, and never found out that the water-rat was in any way different from the other; yet I understand naturalists class them separately, though their colours must be similar.
While living at the Warren there was not a mouse to be seen for a whole twelvemonth or more. Then some one reported seeing a mouse among the tussocks; in a few days more were noticed; then numbers all about, in the grass and in every corner of the house.
After this I had nearly a year's experience at gold-digging on our first goldfields near Collingwood, Nelson. Here in the camps were both rats and mice, although the country was mostly covered by the virgin forest. On my return to Canterbury Province I found my way to the back of the first range of westward mountains previously mentioned, and started a small sheep-run, bounded by the rivers Waimakariri, Poulter, and Esk, there being other large mountains still to the westward, in fact all around. Here the rats acted differently, though I had no suspicion they were a different kind. These came in crowds around the dwelling, so much so that, having stored the flour—which was very precious owing to the difficulty of packing it in—on beams overhead, I made myself a lance by lashing a large packing-needle to a long stick, and, when lying in bed, having the light burning, would spear the rats as they frolicked about, scattering the flour-dust over me. One starlight night I went outside and was standing near a small native-birch tree. On looking towards the clear frosty sky the boughs of the tree were well defined; but the whole tree was thickly covered with apples. I rubbed my eyes and looked again: they still were there—quite a plentiful supply of fruit. I got a long pole which was near by and gently touched one of the apples, when it gave a squeak, and all the fruit
vanished in a twinkling. I rushed to get my dog, but all had cleared out. There were several sheepskins hanging in the lower boughs of the tree, and the rats, busy eating them, on hearing me coming had run aloft and tucked themselves up on the smaller boughs. I candidly confess that it was a case of complete mystification, and instead of hitting hard and making sure of one they were all allowed to escape.
Here, as before, were no mice for months, when they suddenly appeared, having crossed large rivers of ice-cold water or mountain-ranges, and were in thousands. The rats cleared away, and we were now pestered with legions of mice. I have heard farm-labourers, when taking down a wheat-stack for threshing, say if many mice were found in the upper part of the stack there would be few or no rats found in the foundation, being driven out by the mice, or not liking their company.
Again I moved, still further into the wilds, going to the head of the New River (Oreti) and the shores of Lake Waka-tipu, Otago. Here were rats which lived under the dead leaves of the prickly “Spaniard,” and possibly fed on the roots. The Spaniard leaves forked into stiff upright fingers about 1in. wide, ending in an exceedingly stiff pricking point. In places where no fire had passed the dry old leaves turned over towards the ground, overlapping each other, making a miniature bell-tent round the parent stem: these were beautiful dry houses for the rats and lizards. Rats were very numerous; and during my first winter here, being snowed in with a short supply of provisions, I was driven to various devices to keep things going. One was to walk out on the snow with my sheep-dog and set him to find one of these natural tents beneath the snow tenanted by a fat rat, which I would poke out with my stick for the dog to catch, continuing this till a good stock of these small deer were collected. I would then go home, make a bright fire, singe and scrape them, and roast slowly on the ashes. When cooked they gave an appetising odour resembling cooked rabbit. After they had cooled down and had been minced up by a tomahawk, they were given to the poultry. By this means I saved my hens alive and kept them nice and fat. One thing I noticed in cutting up the rats: the paunch or stomach was full of a tanglement of what seemed to be white worms of a pin-wire look, and, perhaps, ¾in. long. I never found out the meaning of this, but considered them a parasite, for the rat masticates its food and would not swallow it whole. These worms had certainly not been bitten. Of course, heating would make them swell and become more apparent. They could hardly be shreds of the Spaniard root. All the rats were similarly affected. The curious part is that I seem to have
noticed no food of any kind in the stomach round which the worms might have been wrapped. This would be about the year 1861.
If I remember rightly it was some three years before the first mouse came. This place was ninety-odd miles from the east coast, from which direction they would probably come. They came just in the same manner as before described. I have now given three undoubted cases of the migration of large bodies of mice, and there is little doubt their natural instinct caused them to travel immense distances, even putting aside comparison with their diminutive bodies. How they avoided or crossed large rivers I do not understand, for I have caused a rat to swim in an ice- or snow-fed river, and the coldness of the water caused it to drown. If the migration occurred in the autumn the water in the rivers would be both lower and much warmer. Up to the time of the migration not a mouse had been seen. Then one was reported as seen in the grass, next day a few more, and then plenty all over the place. The plan of these migrations is not carried out after the manner of troops, marching shoulder to shoulder, but each little beast is dodging along from cover to cover, after the manner of sharp-shooters in advance or on the wings of an advancing army.
These periodic migrations of animals have no doubt been the means by which large continents became stocked over their whole area in those parts suitable to the particular animal occupying them. What influences them, and how they communicate with each other to appoint a day for a general move, is a problem as yet unsolved. Things may occur round about us which have no special significance to our understanding, unless by accident, as it were, the proper key is placed before us.
Rats in this district came into the house—whether the same as those living under the Spaniards I do not know. At the house of one of my neighbours living near Lake Te Anau, some thirty miles away—for people then were few and far between—they killed and salted a lot of beef for winter use, and then hung the pieces by flax-strips to the round battens of the thatched roof. When visiting there I was shown this large array of joints, and told to examine them well. There seemed nothing unusual about them, but on a piece being taken down it proved to be only a shell of outer crust, the whole centre having been eaten away by rats, who proved too cunning to cut away the string by which the meat was suspended. After the advent of mice the rats became less numerous, as was the result in other cases; they must have moved westward into the alpine ranges, before the army of mice.
Recently there has been a plague of rats in Lincolnshire,
England, and some have said the cause was owing to shipments of weasels to New Zealand. From their being in such numbers (one farmer poisoning thirteen hundred in his yard during one night), it is evident that it is not from natural increase, but the result of an ordinary migration.
I lived in the South Island over twenty years and never found a Black Rat (Mus rattus), but, on coming to Hawke's Bay, I soon noticed them; as also the common Norway Rat (Mus decumanus), which is said formerly to have found its way, by ship, to England, and to have superseded the black rat or destroyed it, which was the rat indigenous to Britain. The black rat seems never to come into buildings or stacks, but to live in the fields or bush. I have taken specimens having a yellow-brown mark or line leading from the angle of the jaw down the breast to each fore-leg. On reading Mr. Rutland's paper, giving an account of the so-called Maori Rat (Mus maorium) in the north of the South Island, I set to work to try and find the same rat in the forests here where I am located—Wimbledon, Hawke's Bay. The grey or brown rats had so great a variety of shades of colour and size that this was no easy matter; and a collection of skins had to be made, which varied so much that, for a time, I could come to no decision. Now, I feel sure we also have Mus maorium, and very likely a second native rat, or, rather, third, counting M. rattus. But as yet I have proved nothing certain about No. 2. There may be various stages of hybridism among these rats with Mus decumanus, which would make a difficulty in fixing on the originals. My new rat, in description, seems to agree somewhat with the M. maorium in Mr. Rutland's paper. For some time, owing to its small size, I thought it the young of the larger species. In colour it is brownish-grey mixed with black hairs; black hairs plentiful from forehead to nose, which is pinkish-skinned; belly dirty-white, also light slate-colour, very dark fur underneath; yellowish-brown stripe down breast-bone (not always); coloured on legs down to claws, which are pink with white hairs; ears are often or always jimped as with small excrescences on edges from disease, but this seems a distinct peculiarity of the species; face broad, outline Roman, possibly from hair standing outward naturally; ridge of bone between ears, on back of head, very prominent, sometimes with patches of black colour on inside of skin; hair on back beautifully iridescent in sunbeam when looked at from a certain angle, giving a bright delicate colour of light-green—in fact, the whole surface of the back looks a beautiful green. It is possible this may also be seen on the coats of ordinary rats; I have not yet put it to the proof. If so, it is worth any one's while to see this wonderful effect—an ordinary grey animal changed to a delicate shade of green by
arrangement of angle of sun-rays and the line of sight. Here is another description from my notes: Male, ears jimped with fighting (?), reddish-brown, with black hairs slightly longer. Short black hairs on head, giving a stand-up look to the coat, as of an animal very cold or sick. (This may be taken as a distinct characteristic of the variety.) Nose and mouth, pink. Under-jaw, belly, inside fore-legs, blue-white, with dark under-down. Faint bar of reddish down breast. Darker-brown colour down front of fore-legs. Dark reddish ring of colour round to inside hind-legs at the hock in the lowest of the long body-hair. Top of back darker than sides. Tail smooth; hardly any short hairs. Toes white; hind-toes with patch of dark colour on middle knuckles. Forehead or front of face looking to project, or rounded by hairs standing out. Whiskers black.
Unfortunately I get no opportunity to observe the habits of these rats, for it is from the dead bodies brought home by the cat that my information is derived. I have seen the heaps of hinau seeds with the minute perforation and covered in sawdust or chippings as described by Mr. Rutland; but any of the rats might have this habit. These rats have not the black hairs of the back projecting twice the length of the other hairs, which. I take to be a distinctive feature of M. decumanus, especially the male.
A curious fact is observable in rats and mice: you will see how closely the feet resemble the human hand (as indicated in their scientific name—M. decumanus); but the thumb on each fore-foot is wanting in the top joint and nail.
In England there are several distinct species of mouse; but how few people see or know them one from another! The ordinary mouse, M. musculus—probably imported; the long-and the short-tailed field-mice; the dormouse, sometimes kept as a pet, but sleeping most of its time, as its name indicates; an exceedingly small species, the harvest-mouse, which builds a covered nest of grasses among the cornstalks or bushes: and two kinds of shrew-mouse—these have noses peculiarly long and sharp-pointed, to facilitate their search after the small insects on which they feed; cats are said never to eat them, although they may kill one by mistake. All but the first-mentioned live in the fields, and do not enter buildings. There are also the black rat, said to be extinct; a grey water-rat, and the Norway rat. There are, thus, ten distinct species inhabiting the one country.
Mr. A. R. Wallace writes, “The Black Rat (Mus rattus), was the common rat of Europe till, in the beginning of the eighteenth century, the large Brown Rat (M. decumanus), appeared on the lower Volga, and there spread more or less rapidly, till it overran. Europe and generally drove out the
Black Rat, which in most parts is now comparatively rare, or quite extinct. This invading rat has now been carried by commerce all over the world, and in New Zealand has completely exterminated a native rat, which the Maoris allege they brought with them in their canoes from their home in the Pacific.” The following measurements have been taken roughly in inches:—
[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]
|Maori Rat.||Black Rat.|
|Snout to root of tail||6 4/16||5⅛||4||5⅜||7 12/16||7 ⅜|
|Length of tail||5 11/16||5 1/8||4 6/8||5 3/8||8||7 1/2|
|11 15/16||10 2/8||8 6/8||10 6/8||15 12/16||14 7/8|
The head of Maori Rat 1 ½in., M. decumanus and rattus 2in., from point of nose to top of head. Hind-leg of Maori Rat, 1in.; of the other two species, 1 ½in. These are not measurements of the bone, but outside the hair—i.e., from tip of nose to terminal hairs for length of body—this makes the tail shorter than would show in the bone-measurement.
[Note.—I have, since writing, taken seven worms from paunch of Black Rat, over 2in. long, stiff and wiry. The sheen of Black Rat is dark-purple.]