WHOOPER SWAN 267 



able both to run and to swim. In at least the great majorit}' of species 

 all the quill-feathers of the wings are moulted at once, so that for some 

 time the birds are quite unable to fly, and are therefore absolutely at 

 the mercy of their enemies, unless they can escape by effectually con- 

 cealing themselves. There is considerable difference in regard to the 

 characters of the plumage, the two sexes in the swans and geese being 

 alike in this respect throughout the year, whereas in most ducks the 

 drake is very dissimilar in colouring to his partner for the greater part 

 of the year. 



Swans constitute a special subfamily — the Cygnina; — of the family 

 Anatidce, characterised by the large size of its members, the great 

 length of the neck, which is as long as or longer than the body, and 

 contains a greater number of joints, or vertebrae (23 to 25), than in 

 any of the other three subfamilies, in which there are less than twenty. 

 The sexes are also ahke in plumage, and the hind-toe is not furnished 

 with a vertical lobe on its lower surface. They are further characterised 

 by having the region round the eyes bare of feathers. Like the geese 

 and many ducks, swans moult all their flight-feathers at the same time, 

 and there is consequently a period when they are unable to fly and 

 are therefore practically helpless and easily captured. The small 

 Coscoroba swan {^Coscoroba Candida) of South America, which was 

 formerly classed with the swans, and connects in some degree that 

 group with the geese, has been, but I think wrongly, transferred to the 

 latter group. 



Swans may be regarded as the most specialised, or advanced group 

 of the order to which they belong, that is to say, they have departed 

 very widely from the primitive type, which is most nearly represented 

 at the present day by the mergansers and their kindred. This is 

 indicated not only by their bodily size and long necks, but also by the 

 complete loss of the diving habit, and above all by the character of the 

 plumage. They have, for instance, when adult, but one dress, which 

 corresponds to the breeding-dress of less specialised birds, and, as 

 already mentioned, is similar in the two sexes ; the non-breeding dress 

 persisting only in the case of the young birds, or cygnets. Further, 

 the adult dress, which is either wholly white or wholly black, or black 

 and white, is evidently an ornamental and conspicuous one ; these birds 

 being sufficiently protected by their size and their habit of keeping to 

 open water, so that a protective livery is unnecessary. All swans 

 feed by plunging the long neck to the bottom of shallow water or 

 as far as it will reach in deeper water, and pulling up vegetable sub- 

 stances with their beaks. AH the British species are white. 



