20 INTRODUCTION. 



this from the Poles to the Equator — is in force during the 

 autumnal and hyenial months. Upon this unerring fact a few 

 words explanatory of the cause can with safety be said. The 

 influence of uncongenial climate for food and propagation is 

 the motive principle of migration, and, to a great extent, rules 

 the breeding season of even our indigenous birds. For instance, 

 the robin or blue tit, which have sought the precincts of man 

 during winter, betake themselves to the mossy burn sides or 

 sheltered plantations on the approach of spring ; and it is wisely 

 arranged by Nature that the young are brought forward generally 

 at the time of the year when their particular kind of food is 

 most plentiful. Therefore, the progress of vegetation, and the 

 consequent display of the insect tribe, essentially operate upon 

 those species that look to these sources for their supply of food ; 

 accordingly, we find the arrival of those birds hastened or retarded 

 by an early or late spring. During the time that insects are in 

 the chrysalis state in one latitude they may be in the mature state 

 in another, and an equalisation of destruction (or living on life) 

 is ordained for the wisest purpose ; and, at the same time, the 

 birds may be equally useful and necessary to the inhabitants of 

 the different countries they visit in the wise and perfect 

 economy of Nature. 



The more we study Mother Nature, the more we are con- 

 vinced that the two laws — search of food and propagation of 

 species, each after its kind, rule all created beings — which, in 

 man (with the addition of his mental instinct, called religion ; 

 and in woman, dress) — assume the names of Gold and Love, or 

 love of gold and pride of position in society. All the rest of our 

 desires are like the incipient toes of the elephant, or hidden 

 thigh-bone of the whale, compared to the perfect and well- 

 defined human hand or foot — migration in the bird being 

 simply emigration in the man, generally impelled by a desire to 

 make money or a better home to live in ; unless when hunting 

 after pleasure or scientific research. For even a cow in a park 

 will shift about in search of uncropped grass to carry on the first 

 law of life. All creatures (including man) follow the same in- 

 exorable law. Only, birds, having the pre-eminent power of 

 flight, carry out their instinctive desires at stated times with 

 much greater facility — hence the word migration. 



Our forefathers were slow to believe that any British-born 

 bird would leave its island home for a foreign one. No doubt 

 certain birds, as the swallows, mysteriously disappeared every 

 autumn ; but it was thought that, like the bat and the bear, 



