BRITISH BIRDS. 71 



From this circumstance it has been said that they 

 discover their danger by the quickness of their 

 scent, which enables them to provide for their 

 safety in time ; but it may partly be ascribed to 

 the quickness of their sight, by which they discover 

 the motions of the sportsman. They moult only 

 once a year, and the young after the first autumnal 

 moult assume the adult livery. There is scarcely 

 any perceptible diiference between the sexes. 



The external characters of the Crow r are well 

 known, and are chiefly as follow : The bill is 

 strong, and has a slight curvature along the top of 

 the upper mandible ; the edges are thin, and sharp 

 or cultrated ; in many of the species there is a 

 small notch near the tip ; the nostrils are covered 

 with bristles ; tongue divided at the end ; three 

 toes forward, one behind, the middle toe connected 

 to the outer as far as the first joint. 



