INTRODUCTORY 29 



The sense of hearing is acute in most birds, though there 

 is no external auricle, such as is met with in most mammals ; 

 and herein birds and reptiles again agree. But in the Owls 

 there are some species which develop prominent folds of skin 

 of a very remarkable character, such as will be found described 

 in chapter XXIII, p. 369. The structure of the ear will not be 

 described in these pages, since this is a subject which belongs 

 to the domain of comparative anatomy and is foreign to the 

 purpose of this book. 



The sense of smell in birds is not, apparently, as a rule, 

 very strongly developed. The evidence so far collected on this 

 head is conflicting. The South American Vultures and the 

 Petrels have both an unusually large olfactory chamber, yet, in 

 the first-named at any rate, it has been satisfactorily demon- 

 strated that their sense of smell is practically nil. They find 

 their prey by sight. The Apteryx has the most complicated 

 nasal labyrinth of all birds, and during feeding keeps up a con- 

 stant sniffing sound, as if seeking to make up for its deficient 

 sight by the use of its olfactory sense ; and a piece of further 

 evidence that this sense is well developed is the fact that the 

 nostrils are placed at the extreme tip of the beak — a position 

 found in no other bird. Nevertheless, experiments on captive 

 specimens have produced no very striking evidence to show 

 that their sense of smell is much better, if at all, than in other 

 birds. Ducks are credited with a keen sense of smell, and in 

 the days when duck-decoys were worked, it was the custom of 

 the decoy-men to burn a sod of peat or other vegetable matter 

 when the wind was blowing towards the fowl, in order that 

 any suspicion of human scent might thereby be covered. 



Birds certainly possess a sense of taste, as is shown by the 

 predilections of captive birds, for example, and the way in 

 which gaudily coloured and nauseous insects are avoided. How 

 much the tongue is used in this matter, and whether tongueless 

 birds like Cormorants and Pelicans also possess a sense of 

 taste, there is no evidence at present to show. 



The sense of touch in birds is confined chiefly to the beak : 

 in reptiles, it may be remembered, the tongue is often used for 

 this purpose. The beak of the Snipe, and of its near relatives, 

 is singularly sensitive, being used as a probe for the discovery 

 of food hidden in mud and swampy ground. 



