222 ANIMAL STUDIES 



domesticated state, but the two beautiful wild swans found 

 in this country are rarely seen. 



207. The herons and bitterns (Herodiones). The herons 

 and bitterns are also aquatic in their habits, but, unlike the 

 swimming-birds, they seek their food by wading. Adapting 

 them for such an existence, the legs and neck are usually 

 very long, and the bill, longer than the head, is sharp and 

 slender. Among the relatively few species in the United 

 States, the great blue heron (Ardea herodias) is widely dis- 

 tributed, and may often be seen standing motionless in 

 some shallow stream on the lookout for fish, or it may 

 wander away into the meadows and uplands to vary its diet 

 with frogs and small mammals. Even more familiar is the 

 little green heron or poke (Ardea virescens), which also is 

 seen widely over the country. The night-herons, as their 

 name indicates, stalk their prey by night, and during the 

 day roost in companies a characteristic common to most 

 herons. The bitterns or stake-drivers are at home in reedy 

 swamps, where they live singly or in pairs, and throughout 

 the night, during times of migration, utter a booming noise 

 resembling the driving of a stake into boggy ground. As 

 a rule, the herons breed as they roost in companies build- 

 ing bulky platforms, usually in trees. The bitterns, on the 

 other hand, secrete their nests on the ground in the rushes 

 of their marshy home. 



208. Cranes, rails, and coots (Paludicolae). In their ex- 

 ternal form the cranes and rails resemble the herons, but 

 in their internal orgrnization they differ considerably. 

 They likewise inhabit marshy lands, but usually avoid 

 wading, picking up the frogs, fish, and insects or plants 

 along the shore or from the surface of the water. The cranes 

 are comparatively rare in this country, yet one may occasion- 

 ally meet with the whooping-cranes ( Grus americana) and 

 sand-hill cranes (Grus mexicana), especially in the South 

 and West. They are said to mate for life, and annually 

 repair to the same breeding-grounds, where they build their 



