2o6 The Bird 



sense of smell most acutely developed, although in both 

 cases it is the delicate nerves of touch in the bill which 

 are most helpful in detecting the presence of the earth- 

 worms which constitute the food of these birds. 



To whatever degree the nostrils of land birds aid 

 their owners in procuring food, it is certain that those 



Fig. 150. — Head of Apteryx, showing tactile hair-like feathers, nostrils at tip 



of beak, and small eyes. 



species which feed entirely on fish, which they swallow 

 whole, have little use for nostrils, except for breathing. 

 Thus Nature, ever on the watch to economize, has re- 

 duced these organs, in such birds as pelicans and cor- 

 morants, and, at least in the adults, the nostrils are com- 

 pletely filled up with bone and horn. 



