The Zoologist/4th series, vol 2 (1898)/Issue 683/Stoats turning white in winter
On February 3rd, 1898, I examined a female Stoat in the flesh, which had been killed in this neighbourhood[1] the day before, and was nearly white. That is to say, it was white, with the exception of the crown of the head, a space round the eyes, and a stripe down the back of the neck—the black part of the tail of course excepted. It closely resembled one figured in 'The Field,' February 20th, 1897. As long ago as 1884 I called attention in 'The Zoologist' to the fact that Stoats turned white in mild winters, with reference to that of 1883–4 (Zool. 1884, p. 112). I then mentioned an example killed on January 19th, 1884, which was white, with the exception of a (chance) narrow light brown mark on the near fore leg. Also another, white, save for a dark patch on the crown of the head. The change is not universal in all the individual Stoats in a given locality. For on the day I handled the above-mentioned white one (four days after it was captured) I saw a specimen in the flesh which did not show a sign of white on the upper parts. In the winter of 1895–6 I received information of two partly white Stoats, one pied, the other white, with the exception of the head. In the mild winter of 1881–2 I observed that the change took place in some examples. But white, or partly white, Stoats are naturally far more common in severe winters. After the hard winter of 1890-1, I saw and heard of a great many. Few reach the birdstuffers until after the severe weather, for Ermine Stoats escape notice until after the snow is gone, when they become very conspicuous.
An interesting question is—Would a Stoat turn white in a winter in which absolutely no cold weather (say, nothing below 30°) occurred? It is worth remembering that during this mild season of 1897-8 we had a few days of sharp frost in the latter end of December, with a good deal of white rimy frost. On two nights I registered 22° at four feet from the ground on a north wall, and on four days it froze all day on the ground in the shade. The change to ermine dress is produced by the white of the belly extending up the sides of the body and over the limbs, until only the top of the head and a band down the middle of the back remain brown. The white then spreads across the lower part of the back (leaving for a time, in some cases, a detached portion of brown near the root of the tail); the spinal line becomes gradually shorter and narrower, and at last disappears. Meanwhile the white on the head has increased, the ears and the region about them have become white, and a space round the eyes and a patch on the top of the head alone remain brown. The latter disappears, and the patches about the eyes decrease, until only a narrow ring of brown round each eye is left. This is actually the last part to turn white. Stoats in this condition have a "spectacled" appearance; I have handled several. One was caught at the end of February or beginning of March, 1891, and another on March 5th, 1894.
In 'The Zoologist' for 1888, p. 140, I published some observations which pointed to the fact that the change from white to brown was effected by a change of colour in the fur, and not by a change or moult of the hairs; and that the change began at the tip and not at the base of the hairs. I believe that the change from brown to white is also effected by a change in colour of the hairs, and not by a change in the coat. A change of coat in severe weather would be inconvenient for the animal.
- ↑ Bloxham, Oxon.
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