26 Introduction. 



species where the aperture is smaller, such an addition is not 

 provided. Another peculiarity in the nocturnal birds of prey is 

 that the two ears are not alike ; the one being so formed as to 

 hear sounds from below, the other from above. This, though an 

 old discovery, is not very generally known, though it is doubtless 

 an admirable help to catch the faintest sound proceeding from 

 every direction; and with such organs the owls are enabled to 

 detect in an instant the slightest rustling of their prey. Next to 

 the owl, perhaps the night-jar (or goat-sucker, as it is commonly 

 though erroneously called) possesses the most acute sense of 

 hearing; this bird is also crepuscular, and seldom hunts for 

 moths till the shades of evening, and, as in the owl, its ears are 

 of a very large size. But there are many other birds gifted 

 with remarkably acute powers of hearing. See the song-thrush 

 descend on the lawn on a damp morning ; watch how he inclines 

 his ear on one side, then hops forward, and again listens, till at 

 length he draws forth the worm which his fine ear had told him 

 was there, and which, alarmed at his hops and peckings, had hur- 

 ried to the surface, supposing they were occasioned by his dreaded 

 enemy, the mole. Or, visit some fine old heronry, and try to 

 penetrate near their chosen nursery without your presence being 

 detected ; these nocturnal birds are not particularly keen of 

 sight during the day, but long ere you can approach them, how- 

 ever cautiously, their keen sense of hearing has told them you 

 are near. Another bird remarkable for possessing this faculty 

 in an eminent degree is the Curlew : of all the shore birds there 

 is not one so difficult of approach as this ; his organs of hearing 

 are so sensitive that it is almost impossible to come near him. 

 And again, the Swedish ornithologist, Professor Nilsson, speaks 

 of the Black-cock as being most acute both in hearing and in 

 sight. Such are some of the innumerable instances one might 

 collect of another sense being possessed by the feathered tribes 

 in extraordinary perfection : that some birds hear more quickly 

 than others is an undisputed fact ; but we shall always find, if 

 we examine into it, that to those the most subtle sense of 

 hearing is given whose habits cause them to require it most ; 



