CLASS AVES (BIRDS). 329 



auk of North America has become extinct within the last 

 century. 



Albatross, Petrels, Shear-waters, Terns, and Gulls (Longi- 

 pennes}. This is a group of aquatic birds with long, 

 pointed wings. They are splendid fliers and some are 

 also good swimmers; but they live about and over the 

 water rather than upon it. They are gregarious, and this 



FIG. 136. Wood duck (Aix sponsa). Photo by Folsom. 



is particularly noticeable at breeding time when they 

 swarm on sandy or marshy shores or upon the rocky 

 coasts, laying their eggs in crude nests or on the bare 

 rock. These are the most common birds of the sea- 

 shore and the high seas. The gulls (Fig. 137) and terns 

 frequent also the inland waters. 



Cormorants and Pelicans (Steganopodes) . These are 



