HABITAT AND MIGEATION. 43 



always live in similar degrees of temperature, passing the winter 

 in hot climates, and the summer in cold. The continual inter- 

 change of birds establishes a communication between all coun- 

 tries, and keeps up a sort of equilibrium of life. The bird pass- 

 ing in summer from the equinoctial climates to the cold regions 

 of the north, and again in winter from the poles towards the 

 equator, knows, by an admirable instinct, the winds and the 

 weather which are favourable to his voyage. He can long foresee 

 the approach of frost, or the return of spring, and learns the 

 science of meteorology from the element in which he almost con- 

 stantly lives. He needs no compass to direct his course through 

 the empire of the clouds, the thunder, and the tempest ; and 

 while man and beast are creeping on the earth, he breathes the 

 pure air of heaven, and soars upwards nearer to the spring of 

 day. He arrives at the term of his voyage, and touches the 

 hospitable land of his destination. He finds there his subsistence 

 prepared by the hand of Providence, and a safe asylum in the 

 grove, the forest, or the mountain, where he revisits the habita- 

 tion he had tenanted before, the scene of his former delights, the 

 cradle of his infancy. The Stork resumes his ancient tower, the 

 Nightingale the solitary thicket, the Swallow his old window, and 

 the Redbreast the mossy trunk of the same oak in which he for- 

 merly nestled. All the volatile species which disappear in the 

 winter do not, therefore, change their climate. Some retire into 

 remote places, to some desert cave, some savage rock, or ancient 

 forest, from whence they sally at the close of winter, and spread 

 themselves through the country. 



Other families of birds do not, properly speaking, emigrate. 

 They content themselves with approaching the southern climates, 

 in proportion as they are pursued by the cold. The species 

 called erratic, such as the Greenfinches of the Ardennes, Larks, 

 Ortolans, other frugivorous races, and especially Parrots, go in 

 troops begging, as it were, their subsistence on the passage. 

 Others follow the track of cultivation, and spread themselves in 

 proportion with the habitations of men. 



Of the birds which emigrate every year, some depart in autumn 

 and return in spring, while others depart in spring and return in 

 autumn. Our insectivorous races, and many gramvorous, finding 

 nothing at the beginning of winter but a soil deprived of its 

 productions, presenting every where the image of desolation and 

 death, are necessitated^ betake themselves to more favoured 

 climes. Those which, through negligence or weakness, remain 

 behind, drag out a miserable existence, and constantly perish 

 from famine in the midst of frost and snow. 



As our summer birds abandon us towards the close of autumn, 

 we receive, at the same time, fresh supplies of feathered hordes 



