CLOTHING OF ANIMALS. 17 



becomes again mottled, and the bird loses much of its 

 beauty. Even the young birds in their autumnal dress re- 

 semble their parents in the mottled plumage, which like- 

 wise becomes white at the approach of winter. 



Among the aquatic birds, similar changes in the colour 

 of the plumage have been observed. The black guillemot 

 ( Uria 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 disappears, 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. 



These changes of colour, which we have already men- 

 tioned, extend throughout the whole plumage of the bird ; 

 but, in some instances, the change takes place on a small 

 part only of the plumage. Thus the little auk (Alca alle), 

 during summer, has its cheeks and throat of a black colour, 

 but in winter these parts become of a dirty white. In this 

 its winter garb, it is often shot on our coasts. Its sum- 

 mer dress induced PENNANT to consider it as a variety, 

 and as such to give a figure of it in his British Zoology. 

 The black-headed gull (Lams ridibundiis) has a black 

 head during summer, as its English name intimates. Du- 

 ring 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 Gull 



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 in those which we have 

 already noticed. The colours of the summer feathers are 



VOL. ii. B 



