OF SELBORNE 179 



crevices, and skimming and squeaking round the 

 precipices. 



As I have regarded these amusive birds with no small 

 attention, if I should advance something new and pecu- 

 liar 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 



