674 CLASS AVES. 



under water, without coming to the surface to respire, they 

 do not reappear but at very considerable distances. Their 

 flight is long and rapid, notwithstanding the shortness of 

 their wings ; but the situation of their feet renders their 

 walk vacillating. Their habitual dwelling is in the Arctic 

 regions of the two worlds, and there it is that they most 

 usually reproduce. They are seen only in winter in tem- 

 perate climates, where their arrival in great numbers is 

 regarded as the prognostic of a severe season. This opinion 

 is doubtless well founded, as they are driven from the north 

 by the density of the ice, which prevents them from obtain- 

 ing their habitual aliment on the lakes and rivers of those 

 climates. 



In spring they return northwards. There is no certain 

 information respecting the places in which they nestle. It 

 would appear that it is in the rushes which border lakes and 

 rivers, between rolled pebbles, in bushes, or even in hollow 

 trees, that the female deposits her eggs, from twelve to four- 

 teen in number. The males, at least in the great species 

 Mergus Merganser {Goosander^ Lath.), separate from the 

 females after the birth of the young, with which the latter 

 form flocks apart. This circumstance has probably given 

 rise to the suspicion of naturalists, that these birds were 

 polygamous. 



The mergansers have but one moulting annually ; but 

 according to M. Temminck, that of the old males takes place 

 in spring, while the females and the young males moult in 

 autumn. 



On the species separately, there is nothing to add to the 

 generalities now given. 



