336 FLAMINGOES, DUCKS, AND SCREAMERS. 
proper. The nesting-season commences in the latter half of May, the usual period 
of incubation being about six weeks; but the young birds are unable to fly before 
the end of August. In diet these swans are mainly vegetarians. 
A considerably smaller bird than the last, this species (C. bewickv) 
may be distinguished by the yellow of the bill not extending below 
the nostrils; the total length being about 50 inches. The general distribution is 
very similar to that of the whooper, although this swan is only an accidental visitor 
Bewick’s Swan. 



















































































































































































WHISTLING SWAN (4 nat. size). 
to Norway, and does not breed in Iceland. Indeed, it is only within the last 
twenty years that its nest and eggs were first obtained; and even now very little 
is known of its breeding-habits, since this swan is even a more northerly bird than 
the whooper. Its note is less loud and harsh than that of the latter, being indeed 
somewhat musical in sound. In winter this swan congregates in enormous flocks, 
which may be numbered by hundreds, or even thousands; and it is at all times 
exceedingly wary and difficult to approach. In both the whooper and Bewick’s 
swan the windpipe is bent upon itself, and is received into a cavity in the front 
of the breast-bone, from which it again emerges to enter the chest; but the 
nature of the folding is different in the two species, and serves to distinguish 
between them. 
