Xll. INTRODUCTION. 



proportionally large and strong, whereby they are enabled 

 to keep long upon the wing in search of their prey; they are 

 armed with strong hooked bills, and sharp and formidable 

 claws; they have also large heads, short necks, strong and 

 brawny thighs, and a sight so acute and piercing, as to en- 

 able them to view their prey from the greatest heights in the 

 air, upon which they dart with inconceivable swiftness and 

 undeviating aim ; their stomachs are smaller than those of 

 the granivorous kinds, and their intestines are much shorter. 

 The analogy between the structure of rapacious birds and 

 carnivorous quadrupeds is obvious ; both of them are pro- 

 vided with weapons which indicate destruction and rapine; 

 their manners are fierce and unsocial ; and they seldom live 

 together in flocks, like the inoffensive granivorous tribes. 

 When not on the wing, rapacious birds retire to the tops of 

 sequestered rocks, or to the depths of extensive forests, 

 where they conceal themselves in sullen and gloomy solitude. 

 Those which feed on carrion are endowed with a sense of 

 smelling so exquisite, as to enable them to scent putrid car- 

 cases at astonishing distances. 



Without the means of conveying themselves with great 

 swiftness from one place to another, birds could not easily 

 subsist ; the food which Nature has so bountifully provided 

 for them is so irregularly distributed, that they are obliged 

 to take long journies to distant parts in order to gain the ne- 

 cessary supplies: at one time it is given in great abundance; 

 at another it is administered with a very sparing hand ; and 

 this is one cause of those migrations so peculiar to the fea- 

 thered tribes. Besides the want of food, there are two other 

 causes of migration, viz., the want of a proper tempera- 

 ture of air, and a convenient situation for the great work of 

 breeding and rearing their young. Such birds as migrate 

 to great distances are alone denominated birds of passage; 

 but most birds are, in some measure, birds of passage, 

 although they do not migrate to places remote from their 

 former habitations. At particular times of the year, most 



