The Natural History of Selborne 251 



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 con- 

 tinually 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. 1 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 thundery 

 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 



1 White correctly observes the many points of difference between swifts 

 and swallows, but the ideas prevalent in his age prevent him from seeing 

 that the differences are fundamental, the resemblances superficial and adap- 

 tive onjy. Since Darwin's time we have learned to take a different view 

 of such questions. ED. 



