174 THE NESTS AXD EGGS OE BRITISH BIRDS. 



maturity. It is almost impossible, with the small 

 amount of space at our disposal, to give an adequate 

 idea of the range of colouration of the eggs of the 

 Cuckoo. Although sometimes met with entirely blue and 

 spotless (like a big egg of a Redstart or of a Hedge 

 Accentor), the more usual ground colour varies from 

 grayish-white to greenish-white, spotted, blotched, and 

 freckled with various shades of olive-brown or reddish- 

 brown, intermingled with minute specks of dark brown. 

 Some varieties closely resemble those of the Sky-lark ; 

 others those of the Pied Wagtail, the Reed Warbler, or 

 the Meadow Pipit. Average measurement, '85 inch in 

 length by 75 inch in breadth. Incubation, performed 

 by the foster-parent, lasts about fourteen days. 



Diagnostic characters : It is simply impossible to 

 give any character by which the eggs of the Cuckoo may 

 be identified. They so closely resemble the colour of 

 those of other species, that no reliable distinction is 

 presented, although it may be remarked, the small, 

 round, nearly black specks are very characteristic of the 

 eggs of the Cuckoo. Their size again is unreliable, for 

 we are always confronted with the possibility that instead 

 of a Cuckoo's ^^^ it is merely an abnormally large variety 

 of that of the foster-parent. When placed in nests 

 where the eggs are very different in colour, however, 

 there can be little difficulty. 



