HOW A BIRD FEEDS. 51 



grebe, one of our British birds which lives on fish, 

 we never find stones, but only feathers. Why this 

 should be so has never been explained. 



The stomach of our common cuckoo appears 

 to be lined with hairs when opened. Examina- 

 tion shows them to be the hairs of certain cater- 

 pillars, which only this bird can eat. 



We have discussed the instruments by which 

 the food is seized, and taken a peep into the 

 mysteries of its digestion, let us, for a space, try 

 and learn something of the means by which it is 

 procured, and of the method by which it is 

 discovered. 



In the case of some birds, it is difficult to say 

 whether sight or scent plays the more important 

 part. The vulture in the past furnished material 

 for much controversy on this point. W^aterton, 

 that most delightful of old-time naturalists, de- 

 voted much attention to this very subject. He 

 held it proved beyond doubt that this bird dis- 

 covered its food by scent, and not by sight. The 

 vulture it must be remembered feeds only upon 

 dead and more or less decaying animal matter^ 

 so that there would be no mistake about the 

 smell as a feature of his diet ! He argued out 

 his case at some length. Most of us now are 

 inclined to believe that Waterton, for once, was 

 wrong. We hold with the view that he tried to 

 oppose, tha^i the bird depends entirely upon 

 sight : a faculty which is developed to an extra- 

 ordinary degree in these birds. Vultures, as is 

 well-known, collect in large numbers in an in- 

 credibly short time on a spot where a few hours 

 before not one Avas to be seen. For instance, 



