CHANGE IN THE COLOUR OF THE cLorniNG.—The dif ference in point of colour between the summer and winter dress of animals is very conspicuously displayed both among the quadrupeds and birds. We are not aware that it has been observed among the cold-blooded animals.
Among quadrupeds, the Alpine hare (Lepus variabilis) is a very remarkable example. It is found, in this country, on the high mountains of the Grampian range. Its sum mer dress is of a tawny grey colour ; but, about the month of September, its fur gradually changes to a snowy white ness. It continues in this state during the winter, and re sumes its plainer covering again in the month of April or May, according to the season. The ermine is another of our native quadrupeds, which exhibits in its dress similar changes of colour according to the season. It frequents the outskirts of woods and thickets. During the summer months its hair is of a pale reddish brown colour ; in har vest it becomes clouded with pale yellow ; and in the month of November, with us, it. is of a snow white colour. Its winter dress furnishes the valuable fur called ermine. Early in spring, the white becomes freckled with brown, and in the month of May it completely resumes its sum mer garb.
Among the feathered tribes such instances of change of colour in the plumage during winter are numerous. They greatly perplex the ornithologist, and have been the means of introducing into the system several spurious species. The white grows or ptarmien (Telrao lagopus) may be produced as a familiar example of this kind of hybernation. This bird, like the Alpine hare, inhabits the higher Gram pians, and is never found at a great distance from the li mits of the snow. In summer its plumage is of an ash colour, mottled with small dusky spots and bats. At the approach of winter the dark colours disappear, and its fea thers are then found to be pure white. In remarkably mild winters the change is sometimes incomplete, a few dusky spots of the summer dress remaining. In spring its win ter garb becomes again mottled, and the bird loses much of its beauty. Even the young birds in their first dress re semble their parents in their mottled plumage, and like them become white at the approach of winter.
Among the aquatic birds similar changes in the colour of the plumage have been observed. The black guillemot
(Urfa grylle), so common on our coasts, is of a sooty black colour during the summer, with a white patch on the wings, During winter, however, the black colour disap pears, and its plumage is then clouded with ash-coloured spots on a white ground. In the winter dress, it has been described by some as a distinct species, under the name of the spotted guillemot. In the more northern regions, as in Greenland, for example, this bird, in winter, becomes of a pure white colour. This is a decided proof of the influ ence of temperature in producing this change of colour. There is a fine example of this bird in its white winter dress in the collection of the Dublin Society, where we saw it a few months ago. It was brought from Greenland by that intelligent and enterprising naturalist Sir Charles Gie secke.
These changes of colour, which we have already men tioned, extend throughout the whole plumage of the bird ; but in other instances, the change extends to only a small part of the plumage. Thus the little auk (?lca alle) dur ing summer has its cheeks and throat of a black colour, but in winter these parts become dirty white. In this its winter garb, it is often shot on our coasts. Its bummer dress induced Pennant to consider it as a variety, and as such to figure it. The black headed gull (Lana ridibun dus) has a black head during summer, as its trivial Eng lish name intimates. During the winter, however, the black colour on the head disappears ; and, when in this dress, it has been regarded by many as a distinct species, under the name of the red-legged In many other birds there is a remarkable difference in point of colour between the summer and the winter plu mage, although not so striking as those which we have no ticed. The colours of the summer feathers are rich and vivid ; those of the winter obscure and dull. This is well illustrated in the Dunlin, (Tringa alpina,) whose summer plumage has much black and rufous colour, but whose winter plumage is chill and cinereous. In its winter dress it has been described as a distinct species, under the tri vial name of T. cinclus, or Purre. Similar instances might be produced in the case of the Wagtails, Linnets, and Plo vers, and a great many other birds.