i6o THE NESTS AND EGGS OF BRITISH BIRDS. 



or other building, on a rafter supporting the roof, or on 

 a stone projecting from the wall, or on a ledge close to 

 the under surface of the tiles. A ledge in a chimney, 

 or even in a much-frequented passage, is sometimes 

 selected. The nest is composed chiefly of mud mixed 

 with bits of straw, open, and lined with dry grass and 

 feathers. In many Continental districts, however, it is 

 made on the same model as that of the House Martin, 

 only more open, and generally attached to a wall in the 

 well-known manner. The Swallow is not a very close 

 sitter, and betrays little anxiety when its nest is 

 menaced, beyond occasionally flying in and out of the 

 building. 



Range of egg colouration and measurement : 

 The eggs of the Swallow are from four to six in number. 

 They are pure white in ground colour, freckled, spotted, 

 and blotched with various shades of rich coffee-brown, 

 and with underlying markings of violet-gray. Usually 

 the markings are pretty evenly distributed, but most 

 thickly so on the larger end, often forming an irregular 

 zone. Some eggs are handsomely blotched, others more 

 finely speckled ; some have the gray markings few and 

 indistinct; others display them more numerous than the 

 brown surface-spots. Average measurement, '82 inch 

 in length, by "54 inch in breadth. Incubation, performed 

 chiefly by the female, lasts from thirteen to fifteen days. 



Diagnostic characters : The rich coffee-brown 

 and violet-gray spots on a white ground readily dis- 

 tinguish the eggs of the Swallow from those of all other 

 species breeding in our islands. The situation of the 

 nest is also very characteristic. 



