460 



COLLEGE ZOOLOGl 



Figure 335. The cormorant on nest. A fish eat- 

 ing bird of considerable economic importance. 

 (Courtesy of Nature Magazine.) 



birds are of considerable importance, and a 

 constant effort is being made to maintain 

 them for sport by intelligent game manage- 

 ment. 



One of the most evident services ren- 

 dered by birds is destruction of weed seed. 

 A very large proportion of the food of birds, 

 however, consists of insects. Practically all 

 the insects devoured by birds are injurious 

 to plants or animals and consequently harm- 

 ful to man. In Salt Lake City a monument 

 has been erected to gulls. The crops of the 

 Mormons in 1848-1849 were threatened by 

 locusts, "Mormon crickets," but the gulls 

 came, ate the locusts, and saved the crops. 

 Another large element in the food of birds 



Figure 336. American egret, Casmerodius, in a cypress swamp in the southern United States. 

 The beautiful feathers, known as aigrettes, are carried only during the breeding season. Killing 

 the parents for the plumes means starvation for the nestlings. Length 41 inches. (Courtesy of 

 American Museum of Natural History.) 



