198 BIRDS OF TUNISIA 



immature examples having been obtained in summer at Massaciuccoli 

 and at Ostia. Females of this species seem to be more often met 

 with than males in Italy. 



It is essentially a marine species, frequenting, as a rule, sandy 

 shores and localities affording suitable nesting-sites. It is gregarious 

 and sociable, sometimes breeding in colonies, though more often in 

 isolated pairs. Its food consists of small molluscs, crustaceans, and 

 marine insects, supplemented to a certain extent by vegetable matter. 

 Its note is said to be a harsh " kor," common to both sexes, but the 

 male also utters a shrill whistle, and the female a " quack" like that 

 of the common Duck. Its flight is rather heavy. 



The present species is somewhat peculiar in its nesting, resorting 

 always for that purpose to a hole or burrow in the ground, often a 

 rabbit-burrow, but occasionally that made by some other animal, and 

 more rarely by the bird itself. Here it deposits from seven to twelve 

 eggs of a creamy-white colour and smooth grained, measuring about 

 70 X 48 mm. In some countries, where this Duck lives in a state of 

 semi-domestication, artificial burrows are made for it by the peasants, 

 who daily collect the eggs laid up to a certain date, after which the 

 birds are allowed to incubate. In addition to the eggs, a certain 

 quantity of the down lining the nest is also taken, and affords a 

 further source of profit, the Sheld-Duck's down being almost as 

 valuable as that of the Eider Duck. Owing to its peculiar nesting 

 habits, this Duck in some parts of England goes by the name of 

 Burrow-Duck. 



TADORNA CASARCA (Linnaeus). 

 RUDDY SHELD-DUCK. 



Anas casarca, Litm. Syst. Nat. iii, App. 224 (1768). 



Tadorna casarca, Macgill. Man. Brit. Oni. ii, p. 163 (1842). 



Casarca rutila, Bonap. Comp. List. Birds Eur. and N. Amer. p. 56 



(1838); Salvadori, Cat. Birds Brit. Mus. xxvii, p. 177; Loche, Expl. 



Sci. Alg. Ois. ii, p. 366 (1867) ; Koeni<.j, J.f. 0. 1888, p. 285. 



Description. — Adult male, spring, from Italy. 



General colour of plumage above and below tawny-orange, paler and 

 more cream coloured on the head, and darker on the back; the neck 



