SWIFT 935 



it generally disappears from England very early in August, though 

 occasionally to be seen for even two months later. 



The Swift commonly chooses its nesting-place in holes under the 

 eaves of buildings, but a crevice in the face of a quarry, or even a 

 hollow tree, will serve it with the accommodation it requires. This 

 indeed is not much, since every natural function, except sleep, 

 oviposition and incubation, is performed on the wing, and the 

 easy evolutions of this bird in the air, where it remains for hours 

 together, are the admiration of all who witness them. Though 

 considerably larger than a Swallow, it can be recognized at a 

 distance less by its size than by its peculiar shape. The head 

 scarcely projects from the anterior outline of the pointed wings, 

 which form an almost continuous curve, at right angles to which 

 extend the body and tail, resembling the handle of the crescentic 

 cutting-knife used in several trades, while the wings represent the 

 blade. The mode of flight of the two birds is also unlike, that of 

 the Swift being much more steady, and, rapid as it is, ordinarily 

 free from jerks. The whole plumage, except a greyish-white patch 

 under the chin, is a sooty- black, but glossy above. Though its 

 actual breeding-places are by no means numerous, its extraordinary 

 speed and discursive habits make the Swift . widely distributed ; 

 and throughout England scarcely a summer's day passes without 

 its being seen in most places. A larger species, C. melha or alpinus, 

 with the lower parts dusky white, which has its home in many of 

 the mountainous parts of central and southern Europe, has several 

 times been observed in Britain, and two examples of a species of a 

 very distinct genus, Acanthyllis or Chxtiira, which has its home in 

 northern Asia, but regularly emigrates thence to Australia, have 

 been obtained in England {Proc. Zool. Soc. 1880, p. 1). 



Among other peculiarities the Swifts, as long ago described 

 (probably from John Hunter's notes) by Home (Fhil. Trans. 1817, 

 pp. 332 et seqq., pi. xvi.), are remarkable for the development of 

 their salivary glands, the secretions of which serve in most species 

 to glue together the materials of which the nests are composed, 

 and in the species of the genus CoUocalia form almost the whole 

 substance of the structure.* These are the " edible " nests so 

 eagerly sought by Chinese epicures as an ingredient for soup, and 

 their composition, though announced many years since by Home 

 (ui supra), whose statement was confirmed by Bernstein (Ad. Soc. 

 Sc. Indo-N6erl. iii. Art. 5, and Journ. fiir Orn. 1859, pp. 111-119), 

 has of late been needlessly doubted in favour of the popular belief 

 that they were made of some kind of sea-weed, Algse, or other 

 vegetable matter collected by the birds.^ It may be hoped that the 

 examination and analysis made by Dr. J. R Green {Journ. of Physiol. 

 vi. pp. 40-45) have settled that question for all time. These re- 

 ^ Hence one species has been called CoUocalia fuciplutga. 



