FAMILY ANATIDAE 



The characteristics which separate this 

 Subfamily from the Surface-feeding Ducks 

 and Mergansers are: 



(a) The Diving Ducks are, generally, fre- 

 quenters of the larger inland bodies of water 

 and of the sea coasts; they feed by diving, of- 

 ten seeking their food at considerable depths; 

 the food is generally less vegetable and in 

 many cases consists mainly of molluscs, shell- 

 fish and comparatively deep-water aquatic 

 plants; with few exceptions, the flesh is less de- 

 sirable than that of the Surface-feeding Ducks. 



(b) Both the Diving Ducks and Surface- 



F*. 8,-Typical Diving Duck ? eedin g Ducks h , ave . the , ". ^oad and flat; 



it is narrow and cylindrical in Mergansers, 



and the lamellae are rigid and sharp-pointed. 



(c) These ducks and the Mergansers are instantly distinguished from 

 the Surface-feeding Ducks in that the hind toe has a pronounced flap or 

 lobe, which is lacking in the River and Pond Ducks; the tarsi are shorter 

 and therefore these ducks are less adept at 



walking on land; the feet, like those of the 

 Mergansers, are larger than those of the Sur- 

 face-feeding Ducks; the legs are set further 

 back on the body, thereby increasing ability 

 in diving and swimming. 



(d) The speculum, or coloured patch on 

 the secondary feathers, is less bright in the 

 Diving Ducks and Mergansers, and generally 

 lacks the iridescence of that of the River and 

 Pond Ducks. 



(e) In rising from the water or land most 

 ducks of this Subfamily patter along the sur- 



FIG. 9.- -Typical bill and foot 



of Diving Duck, showing 



hind toe with lobe 



face for some distance before clearing, whereas the River and Pond 

 Ducks leave the water with a strong, vertical, upward bound. 



MERGANSERS 



Subfamily Merginae 



There are distributed throughout the 

 world, chiefly in the Northern Hemisphere, 

 nine forms of Mergansers, of which three 

 are regularly found in North America. 



This Subfamily is characterized by the 

 following features: 



(a) The duck-like form is modified to 

 more slender and stream-lined proportions 

 to give increased ability for underwater 



FIG. 10. Typical Merganser 



