BBEEDING HABITS OF THE SWIFT. 385 



Swifts over the possession of the nesting-holes will account for 

 many an egg being knocked out of the nests. I have also 

 noticed that the Swifts themselves, when disturbed, have a habit 

 of fluttering and scrambling about in their nesting-holes, so that 

 eggs may sometimes be dislodged by the parent birds. 



The question also occurs — Are birds which nest in deep 

 holes or crevices known to lay in each other's nests ? This takes 

 place most usually in the case of birds which make open nests on 

 the ground, especially those which breed in colonies, as Gulls 

 or Terns ; also in the case of Game-Birds, as Partridges or 

 Pheasants ; and Water-Birds of various species, as Ducks, Coots, 

 Moor-hens, &c. It certainly occurs less frequently with those 

 which build their nests in trees or bushes, as do most Passerine 

 birds ; and, I should say, very rarely, if at all, in the case of 

 birds which nest in holes. This, however, is a subject upon 

 which further investigation is desirable. 



The nesting materials which Mr. Jourdain mentions as used 

 by the Swift agree entirely with my own experience. Feathers, 

 small straws, and pieces of rubbish are always found — ^just such 

 materials as would be blown into the air on windy days ; but I 

 have also generally found a quantity of the blossoms, catkins, or 

 bud-scales of various trees, especially those of the oak and beech, 

 which are blossoming just at the time when the Swifts are build- 

 ing, and whose blossoms are frequently blown about by the 

 strong breezes of the end of May. These materials are always 

 cemented together by a glutinous substance secreted by the bird. 

 Indeed, without this curious provision of nature, the scanty 

 materials could hardly be woven together into a nest at all ; and 

 it is no doubt intended to keep the substance of the nest from 

 being dispersed, as the Swift generally builds in a large and 

 irregular crevice, and is not able to lay down a large bed of 

 materials filling the entire bottom of the hole, after the man- 

 ner of the Tits or the Creeper ; nor, as in the case of the Sand- 

 Martin, would the loose feathers and straws be held together b}'- 

 being placed in a small and comfortable space. 



There is no doubt a good deal yet to be learned about the 

 nesting habits of these interesting birds, for the difficulty of 

 observing them is very great, owing to their breeding in dark 

 holes and crevices out of sight, and often in rather inaccessible 

 situations. 



