i86 THE NESTS AND EGGS OF 



prevalent among birds nesting in holes where space is 

 limited — and pure white when blown. Before the contents 

 are removed they have a beautiful pearly appearance. 

 Average measurement, 2*i inches in length, by \"j inch 

 in breadth. Incubation is performed, it is said, by the 

 female alone, and lasts thirty-one days. Further research 

 may show that the male bird occasionally sits upon the 

 eggs. 



Diagnostic characters : As a rule the eggs of the 

 Hooded Merganser are larger than those of the Wood 

 Duck — a species that also nests in hollow trees — but 

 they should always be carefully identified. The down 

 is an important point, and is very pale gray in colour. 

 The colour of the eggs will readily serve to distinguish 

 them from those of the Smew, the Buffel -headed Duck, 

 and the Golden-eye. 



Family ANATID.^. Genus Mergus. 



Sub-family MERGINAL. 



S M E W. 



Mergus albellus, LinficBus. 



(British : Rare nomadic autumn and winter migrant.) 



Single Brooded. Laying season, end of June and in July. 



Breeding area : Northern Palaearctic region. The 

 Smew breeds in Finnish Lapland, and in Russia as far 

 north as the Arctic Circle, and as far south as about lat. 

 60'' in the west, and the valleys of the Kama and Lower 

 Volga in the east. In Asia it breeds across Northern 

 Siberia, south of the Arctic Circle or the limits of 

 forest growth, but its southern limits appear to be 

 undetermined. 



