452 



COLLEGE ZOOLOGY 



for this type of life. They are generally 

 known as swimmers, divers, shorebirds, and 

 waterfowl. Perhaps the type most conspicu- 

 ously adapted for an aquatic existence is the 

 penguin (Fig. 314). The forelimbs are modi- 

 fied as paddles for swimming under water; 

 the feet are webbed; the cold water can be 

 shaken entirely from the feathers; and a layer 

 of fat just beneath the skin serves to keep 

 in the body heat. They feed on marine in- 

 vertebrate animals. Loons (Fig, 322) are 

 large birds that swim and dive with great 

 agility. Grebes are smaller than loons and 

 are also excellent swimmers and divers. 

 Albatrosses (Fig. 305) possess exceptionally 

 long and narrow wings. They are such strong 

 fliers that they rarely come to land except 

 for nesting. 



The white pelican possesses a huge mem- 

 branous pouch between the branches of the 

 lower jaw, with which it scoops up small 

 fish. Among the common wading birds are 

 the herons (Fig. 324) and bitterns. They 



Figure 323. California brown pelican. Note the 

 pouch that hangs from the lower bill; this serves as 

 a scoop net for capturing and storing fish. (Courtesy 

 of N.Y. Zoological Society.) 



possess long legs, broad wings, and short 

 tails. Here also belong the flamingos (Fig, 

 322) that inhabit the tropics. They are 



gregarious birds, congregating in thousands 

 on mud flats, where they build their conical 

 mud nests. Most species have rosy-white 

 plumage with scarlet wing feathers. The 

 ducklike birds (Fig. 305) are adapted for 

 swimming, with short legs and fully webbed 

 front toes. Their young are entirely covered 

 with down and can swim or run about soon 

 after hatching; they are precocial. In North 

 America and other parts of the world are 

 swans, geese, river ducks, sea ducks, and 



mergansers. 



Figure 324. Great blue heron. Long neck, long 

 legs, slender body, and a stilettolike bill are charac- 

 teristics of this species; this bird is an expert fisher- 

 man. (Courtesy of N.Y. Zoological Society.) 



The marsh birds are mostly of the wading 

 type with incompletely webbed front toes. 

 They include the rails, gallinules, coots, 

 cranes, limpkins, and trumpeters. The or- 

 der of shorebirds contains a varied assem- 

 blage of plovers, sandpipers, gulls, terns, 

 puflins, auks (Fig. 305), etc., most of 

 which frequent fresh or salt water. The 

 jacanas are tropical shorebirds, with very 

 long toes and claws enabling them to walk 

 over lily pads without sinking. The puffins, 

 murres, and auks spend a large part of their 

 existence at sea. Most are excellent swim- 

 mers and divers, but very awkward on land. 



The great auk, Pinguinus impennis, be- 

 came extinct in 1844, when the last one ap- 



