260 ALLEN'S NATURALIST'S LIBRARY. 



the bill does not appear till the bird is at least two years old, 

 and commences to breed for the first time. The knob in- 

 creases in size with age. 



Nestling. Brown above, white beneath, with a slight 

 yellowish tinge ; forehead and sides of face white ; in the 

 middle of the back a white patch ; a white patch on each 

 side of the lower back, and a white streak along each side of 

 the rump. 



Characters. The striking contrast of colours in this beautiful 

 species, to say nothing of its red bill and frontal knob, render 

 it easy of identification, and there is no other species of 

 British Duck with which it can possibly be confounded. 



Hybrids. The Common Sheld-Duck has been known to 

 interbreed with the South African Sheld-Duck (Casarca catia) 

 and with the Wild Duck (Anas boscas). Cf. Salvador!, Cat. B. 

 Brit. Mus. xxvii. p. 173. 



Range in Great Britain. The present species occurs in suit- 

 able localities on most parts of the British coasts, and is found 

 breeding in those portions which afford it suitable nesting- 

 places. Mr. Ussher states that it breeds in small numbers on 

 the coasts of Donegal, Londonderry, Antrim, Down, Dublin, 

 VVexford, Waterford, Kerry, Clare, and Mayo. In winter con- 

 siderable numbers visit us from the north of Europe, and the 

 bird is then killed in many parts of Great Britain, in which it is 

 not seen in the summer. 



Range outside the British Islands. The Sheld-Duck is a Palse- 

 arctic bird, and breeds on the coast of Norway up to 70 N. 

 lat., being only occasionally met with in the Faeroes. It nests 

 in Sweden, Denmark, the Baltic provinces, and Holland, as well 

 as on the shores of France and Spain, but in other parts of 

 Europe and the Mediterranean countries it is only known as 

 a winter visitor. It is, however, again resident on the shores 

 of the Black and Caspian Seas, and its range extends in locali- 

 ties suited to its habits, through Central Asia and Southern 

 Siberia to Mongolia and Japan. 



Habits. From its habit of nesting in rabbit-holes in many 

 parts of the country the Sheld-Duck is known as the " Burrow 

 Duck," and the nest is often constructed at the end of a 



