NATUEAL HISTORY OF SELBOENE. 131 



As I have regarded these amusive birds with no small attention, if I 

 should advance something new and peculiar with respect to them, and 

 different from all other birds, I might perhaps be credited ; especially 

 as my assertion is the result of many years exact observation. The 

 fact that I would advance is, that swifts tread, or copulate, on the 

 wing ; and I would wish any nice observer, that is startled at this 

 supposition, to use his own eyes, and I think he will soon be convinced. 

 In another class- of animals, viz. the insect, nothing is so common as to 

 see the different species of many genera in conjunction as they fly. The 

 swift is almost continually on the wing ; and as it never settles on the 

 ground, on trees, or roofs, would seldom find opportunity for amorous 

 rites, was it not enabled to indulge them in the air. If any person would 

 watch these birds of a fine morning in May, as they are sailing round 

 at a great height from the ground, he would see, every now and then, 

 one drop on the back of another, and both of them sink down together 

 for many fathoms with a loud piercing shriek. This I take to be the 

 juncture when the business of generation is carrying on. 



As the swift eats, drinks, collects materials for its nest, and, as it 

 seems, propagates on the wing, it appears to live more in the air than 

 any other bird, and to perform all functions there save those of sleeping 

 and incubation. 



This hirundo differs widely from its congeners in laying invariably 

 but two eggs at a time, which are milk-white, long, and peaked at the 

 small end ; whereas the other species lay at each brood from four to six. 

 It is a most alert bird, rising very early, and retiring to roost very late ; 

 and is on the wing in the height of summer at least sixteen hours. In 

 the longest days it does not withdraw to rest till a quarter before nine 

 in the evening, being the latest of all day-birds. Just before they retire 

 whole groups of them assemble high in the air, and squeak, and shoot 

 about with wonderful rapidity. But this bird is never so much alive as 

 in sultry thundry weather, when it expresses great alacrity, and calls 

 forth all its powers. In hot mornings several, getting together in 

 little parties, dash round the steeples and churches, squeaking as 

 they go in a very clamorous manner ; these, by nice observers, are 

 supposed to be males serenading their sitting hens ; and not without 

 reason, since they seldom squeak till they come close to the walls or 

 eaves, and since those within utter at the same time a little inward note 

 of complacency. 



When the hen has sat hard all day, she rushes forth just as it is 

 almost dark, and stretches and relieves her weary limbs, and snatches 

 a scanty meal for a few minutes, and then returns to her duty of 

 incubation. Swifts, when wantonly and cruelly shot while they have 

 young, discover a little lump of insects in their mouths, which they 

 pouch and hold under their tongue. In general they^feed in a much 

 higher district than the other species ; a proof that gnats and other 

 insects do also abound to a considerable height in the air ; they also 

 range to vast distances, since locomotion is no labour to them who are 

 endowed with such wonderful powers of wing. Their powers seem to 

 be in proportion to their levers ; and their wings are longer in pro- 

 portion than those of almost any other bird.,. When they mute, or case 



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