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A YEAR IN SCIENCE 



ming, and still others for wading. In wading birds, 

 such as the plover, heron, and stork, the legs are very 

 long. In perching birds there are three toes in front 

 and one behind. This hind toe is important in holding 

 the foot in place. The tendons and the muscles in the 

 foot and leg are so arranged that they are self locking. 

 Consequently even when asleep, such birds remain bal- 

 anced on the perch. 



Permission of Field Museum of Natural History, 

 Fig. 114. Adaptations in the feet of birds. 



The form of the bill varies according to the habits of 

 the bird. A duck has a flat bill for pushing through 

 the mud ; the woodpecker has a sharp bill for piercing 



