Order ANSERIFORMES. 



Family ANATID^ or SWANS, GEESE, DUCKS, and 

 MERGANSERS. 



The Ducks and their allies are an extensive and very clearly 

 defined group of birds. They are perhaps most nearly allied to 

 the Herons by way of the Flamingoes, and to the Rails by way of 

 the Screamers. They are also more or less closely allied to the 

 Raptores and the Pelicans. Their sternum contains only one 

 notch on each side of the posterior margin. In the modification 

 of their cranial bones they are desmognathous. In their pterylosis 

 they are characteristic and well defined ; whilst in their myology 

 and digestive organs they are perhaps most closely allied to the 

 Grebes (Podicipediformes) and the Herons (Pelargiformes). 



The most important external characteristics of the Ducks and 

 their allies are their peculiar laminated bill, short legs, webbed 

 feet, and dense compact plumage. Primaries ten in number; 

 rectrices variable in this respect, Moult single in autumn. In 

 the Ducks the males moult their small feathers twice in twelve 

 months ; the Geese, Swans, and Sheldrakes have only one moult. 

 Quills moulted so rapidly as to incapacitate the bird for flight. 

 Young hatched covered with down, and able to run and swim 

 almost immediately. Progress of young to maturity : (Geese), do 

 not differ very remarkably from their parents in colour except in 

 those species where the adults are characterised by violent con- 

 trasts of colour ; (Ducks), in first plumage very closely resemble 

 the old female, and acquire nearly adult plumage after their first 

 autumn moult ; (Swans), in first plumage are grayish brown, a 

 plumage which they carry until their second autumn, when the 

 adult white attire is assumed. 



Number about i6o species or less; almost cosmopolitan, but 

 rare in species in the tropics, except during the period of the 

 northern winter. 



