THE KOTCHE. 295 



the plumage of northern birds, such as the guillemots, may, 

 on the other hand, be considered as more immediately pro- 

 duced by the seasons. 



THE EOTCHE (Mergulus melanoleucos). 



The common rotche, or little black and white auk, is still 

 smaller than the black guillemot ; and though, like the guille- 

 mots, an expert diver, it differs from them in many of its 

 characters. When it appears with us, it inhabits nearer the 

 shores than the divers and guillemots ; and as its bill is less 

 of a fishing spear than theirs, and more resembles the bills of 

 the Gallmse, it is probable that its food is more littoral, and, 

 as such, more under the influence of the seasons. At all 

 events, its migration appears to depend upon or to be modi- 

 fied by other causes. It visits the British shores in the 

 winter, and generally retires to more northerly places to 

 breed. In the summer plumage, the breast, belly, tips of the 

 secondary quills, and a spot above the eye, are white : the rest 

 of the plumage is black. In winter, the throat, sides of the 

 neck and flanks, become white, though seldom entirely pure 

 upon our shores ; the black on the upper part also becomes 

 greyish ; and it may become white in latitudes where the 

 winter is more severe and prolonged. 



The length of the rotche is about nine inches, the extent 

 of the wings about sixteen, and the weight about five ounces ; 

 so that it is much better adapted for flight than the guille- 

 mots, and it accordingly spends much more of its time on the 

 wing. Its bill is only half the length of the head, very little 

 arched; and from its resembance to that of poultry, the 

 bird is presumed to feed upon small crabs, and other little 

 animals, that float near the surface. It breeds in the holes 

 of rocks, in which it deposits two eggs, which are of a spotless 

 bluish green colour. 



Along the margin, and in the openings between the fields 



