208 BRITAIN'S BIRDS AND THEIR NESTS. 



stations ? The Swift is incapable of perching, for all its 

 four toes are pointed forwards. This unique character- 

 istic is found only among the Swifts of the typical genus, 

 and nowhere else in the whole bird-world. For clinging 

 to a vertical surface it is an admirable arrangement. The 

 Swallow tribe constantly utter low twittering notes, but 

 also possess the power of true song. The Swift has a low, 

 short note, too, but its usual cry is a loud, wild scream, 

 ' Swee-ree ' — in no way Swallow-like — and song it has none. 

 The possession of feet for perching and of true song- 

 muscles are important characteristics of the great Order 

 of which the Swallows form a family, while the Swifts 

 find their nearest allies in the Humming-Birds of tropical 

 America, and are with them included in this present 

 ' Order of odd families.' 



The Swift and the Swallow both subsist on small insects 

 caught on the wing by the method of rushing through 

 the air with widely gaping mouth ; many are caught be- 

 fore any are swallowed, the sticky interior of the mouth 

 keeping them prisoners meanwhile. Both birds are pro- 

 vided with long, narrow, curved wings, a small bill, and 

 an enormous 'gape.' Here the resemblance practically 

 stops. The general colour scheme of the plumage, as well 

 as the details of the moulting, are quite different. The 

 nesting economy of the two is very dissimilar, and the 

 general habits show little or no resemblance, apart from 

 what is consequent on their common mode of life. Both 

 are of necessity only summer visitors to the British Isles ; 

 but while the Swallow shows close correspondence with its 

 allies in the times and manner of its comings and goings, 

 the Swift arrives considerably later than any of them, and 

 leaves very much earlier. The single ' early Swift,' more- 

 over, is a rarity, for the birds usually arrive in a body at 

 the nesting-site of the colony. The dates of arrival at two 



