ORDER ACCIPITRES. Ill 



the reason why many birds, as well as the owl family, are noc- 

 turnal. A considerable number are also partial to twilight, as, 

 for instance, the majority of the grallse. 



With means like these, the bird is enabled to travel in the 

 air. Its specific lightness ; the vigour of its wings ; the nimble- 

 ness of its motions ; the directions of its tail, which serves as a 

 rudder ; permit it to ascend, to descend, to turn, to flutter in 

 all directions, to cut in a right line, to shave the surface of the 

 earth or water, to hide itself in the clouds, and, in a word, to 

 sport at its pleasure in the immense field of the atmosphere. 

 Sometimes it will descend to gather the seeds in the fields, and 

 sometimes, elevating itself above the clouds, respire the pure and 

 serene air under the azure sky, while terrestrial animals are 

 battered by the tempest and menaced by the lightning. Birds 

 of high flight, enveloped in a warm, thick, and downy plumage, 

 fear nothing of the piercing cold of the loftiest regions of our 

 atmosphere. It is remarkable that birds employed in falconry, 

 which their trainers are desirous of preventing from flying to 

 too great an elevation, never mount but to a moderate height 

 when deprived of the feathers of the belly and sides, because they 

 are then afraid of the effects of cold. The water-fowl, provided 

 with a thick down and an oiled plumage, which do not suffer 

 the moisture to penetrate, plough the surface of the seas and 

 lakes with perfect safety. Nature, moreover, has provided all 

 birds with a certain gland, Avhieh distils over the crupper an 

 oily humour, with which they anoint their plumes, passing 

 them between their beaks. But this humour is peculiarly 

 abundant in aquatic birds. Their skin even imbibes it, and 

 thence acquires a rancid flavour ; and it insinuates itself 

 through the entire plumage. From this it occurs that these 

 birds, though perpetually immersed in the water, are never 

 washed by it, the liquid rolling over them without moistening 

 their plumage, even though they seem desirous of it — 



" Et studio incassuin videas gestire lavando." 



