176 THE NESTS AND EGGS OF BRITISH BIRDS. 



straws or grass-bents lined with feathers, the whole some- 

 times being matted together with viscid saliva. In many 

 cases the old nest of a Sparrow or of a Starling will be 

 utilized, or the materials annexed. I do not think that 

 the Swift voluntarily glues its nest together with saliva, 

 but in conveying the materials and arranging them they 

 get more or less coated with the abundant secretion. 

 Swifts breed in colonies of varying size according to the 

 amount of accommodation afforded. Sometimes odd 

 pairs may be met with breeding isolated here and there ; 

 sometimes the nests are far apart, even in the same 

 building or village, but all through the summer the birds 

 themselves continue gregarious. 



Range of egg colouration and measurement : 

 The eggs of the Swift normally are two in number, but 

 occasionally three and even four have been found. 

 They are white and spotless, very narrow and elongated, 

 rough in texture, and with little or no polish. Average 

 measurement, I'O inch in length by "65 inch in breadth. 

 Incubation, performed by both sexes, lasts seventeen or 

 eighteen days. 



Diagnostic characters : The size, white colour, 

 and elongated shape, readily distinguish the eggs of the 

 Swift from those of all other birds breeding in our 

 islands. 



