232 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



base than tip of bill. Juvenile with loral feathering scanty. Trachea 

 not entering carina sterni which is simple. Other structure as in 

 C. cygnus. 



Soft parts. — JBill (ad.) pinkish-red tinged orange, nail, knob, 

 area around and behind nostrils, base and cutting edge black, 

 under mandible black basally with an irregular flesh-coloured area 

 towards tip ; bill (nestling) black with yellowish nail ; legs and 

 feet dark grey ; iris hazel. 



Characters. — No subspecies. Distinguished by large size and 

 coloration of bill. Adult male in breeding-season with enormously 

 enlarged knob at base of bill. 



Breeding -habits. — In wild state breeds on islands in swamps and 

 on reed-grown lagoons, but in semi-domesticated state almost any- 

 where near water ; sometimes in colonies. Nest. — Large heap of 

 water-weeds and vegetable remains from water, with depression at 

 top, usually on dry land close to water, but sometimes in water. 

 Eggs. — Normally 5-7, but cases of 8-12 on record ; over 9 possibly 

 due to two females ; not white like other British Swan's eggs, but 

 covered with bluish-green tinge. Average of 50 eggs, 114.5x73.1. 

 Max.: 122x77.1 and 119x80. Mn. : 105x73 and 112x70 mm. 

 Breeding -season. — Usually in second half April in British Isles, 

 sometimes not till May. Incubation. — Practically entirely by female, 

 male occasionally taking small share. Period apparently from 34 

 or 35 days to (occasionally) 42^3. Single-brooded. 



Food. — Almost entirely vegetable ; water-vegetation ; Confervce 

 and Characice, Callitriche aquatica, Potamogeton, also rhizomata of 

 reed, arrow-head and stalks and roots of other aquatic plants. 

 Insects and their larvae, worms and snails said to be eaten ; frogs, 

 toads and young water-birds occasionally killed but not eaten. 



Distribution. — British Isles. — Originally introduced and now 

 resident and generally distributed. Truly wild birds may some- 

 times occur. 



Distribution. — Abroad. — Breeds in a wild state in south Scan- 

 dinavia, Denmark, north Germany, central and south Russia, 

 south-east Europe, and eastwards to Turkestan and Mongolia. 

 Migratory, and wintering in basin of Mediterranean, on Caspian Sea 

 and eastwards, occasionally in north-west India. Pound in a semi- 

 domesticated state in many places. 



[Note. — There is no doubt that the so-called Polish Swan (" Cygnus 

 immutabilis ") is only an aberrant domesticated and semi-domesticated Mute 

 Swan.] 



[Note. — An immature bird, supposed to be an example of the American 

 Trumpeter Swan, Cygnus buccinator Richardson, was shot near Aldeburgh 

 (Suffolk) in Oct., 1866, and is in the Museum of that town (Yarrell, iv, p. 322 ; 

 Saunders, p. 416). Examples of the American Whistling Swan, Cygnus 

 columbianus Ord, are stated, " on weak evidence," to have been found in 

 shops of Edinburgh poulterers (Yarrell, iv, p. 322 ; Saunders, p. 416).] 



