360 THE SWIFT 



several have been observed clinging in clusters about any tall build- 

 ing. " This clustering habit is very peculiar, some of the festoons thus 

 formed being from eighteen inches to two feet in length. Sometimes 

 the outer and more benumbed individuals drop down from the general 

 mass." 1 The birds obviously cluster for warmth, and in clinging they 

 are well served by their strong claws. 



The hen roosts, of course, in the nest-hole, and there, after some 

 eighteen to twenty days' incubation, the young are born. Whether 

 the hen only, or both parents, habitually feed the young is still un- 

 certain, the evidence conflicting. The fact that birds have been seen 

 coming to the nest in quick succession points to the latter view as 

 being correct. 2 



Young swifts resemble the young of the Hirundinidce in being fed 

 with bundles or balls of flies which are thrust down their throats. 

 They differ in being fed at much longer intervals, several hours some- 

 times intervening between their meals. On the other hand, the 

 meals are large, each of the two or three young birds being fed two 

 or three times alternately, 3 the whole process, according to Weir, 

 taking from three and a half to four minutes. 4 "Swifts," writes 

 Gilbert White, "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." 5 The pouch makes itself 

 externally visible by the bulging chin, as in the case of the Crows. 

 As the young are fed at each visit two or three times in succession, 

 the bundle must in some way be divided before distribution. It 

 would be interesting to know how this is effected. 6 



1 Zoologist, 1903, 267. 



2 P. C. R. Jourdain (in litt.). See also Nature Notes, 1801, 50-53 (Aubrey Edwards). In the 

 Field, 1898, xci. 910, a correspondent states that he has over and over again seen three swifts 

 feeding the young at the nest. It is difficult to believe they were all hens. Perhaps there 

 were two nests in the hole. 



' Nature Notes, 1891, 27-30 (Aubrey Edwards). 

 4 Macgillivray, History of Birds, iii. 625. 

 4 Letter to Harrington, September 28, 1774. 



For the feeding habits of the alpine-swift see above, p. 304. Swifts, it may here be noted, 

 swallow the excreta of the young, according to Mr. Aubrey Edwards, loc. cit. 



