INTRODUCTION. XI 



Like quadrupeds, birds may be classified asgranivorous, carnivorous, 

 and mixed feeders, or those that partake of both. Granivorous birds 

 are furnished with larger and proportionally longer intestines than 

 carnivorous species. Their food first enters a craw where it reaches 

 entire, but soon undergoes partial dilution by a peculiar liquor 

 secreted from the glands thence enters another stomach, and even- 

 tually the gizzard or true stomach, where, with the aid of powerful 

 muscles, thick and powerful membrane and stones it is triturated 

 and becomes fit for the action of the gastric juices. 



In their habits birds are either monogamous or polygamous, the 

 latter exists generally among the Rasores or Gallinacea. Some again 

 live a solitary life till the breeding season, when they begin their 

 courtship and live in pairs, whilst their united efforts are necessary 

 in forming their temporary habitation and in rearing their offsprings. 

 There are also some, as the cuckoo, which leave their eggs to the 

 care of a foster parent. Birds generally evince great affection for 

 their young, and do not leave them till they can feed themselves. A 

 great number or the majority of those known to inhabit India and its 

 dependencies quit the country for the purpose of breeding. 

 Each species associate in flocks and aided by their keen sight, to- 

 gether with the advantage they possess of flying at considerable 

 heights in the air, they are enabled with their instinctive knowledge to 

 discover the route they are to take to migrate 'taking, probably, as a 

 guide, the appearance of the atmosphere,, direction of winds, &c.; 

 so that without recourse to improbable modes it is not difficult to 

 form an idea of the speed at which they go in transporting themselves 

 to far countries by crossing vast ocean tracts. Without the means of 

 conveying themselves from one place to another they could scarcely 

 subsist for the reason that climatic influences affect their food-supply. 

 This may also be said to be one of the reasons for migrating. Besides 

 the want of food, other causes of migration are, the want of a proper 

 temperature of air and a convenient situation for the great work of 

 breeding and rearing their offspring. They either remove from one^ 

 country or climate to another or from the inland districts to hills, 

 forest regions or to sequestered rocks or islands in the sea, or to 

 vast sandy plains far removed from, or in the vicinity of, the sea .or 



