307 ) 



THE BIEDS OF THE DISTBICT OF STAINES. 

 By Graham W. Kerr. 



(Continued from p. 234.) 



Cuckoo (Cuculus canorus). — During summer the Cuckoo is 

 numerous all along the Thames Valley, and I have already stated 

 that in the earlier part of summer the eggs are deposited with 

 the Sedge-Warbler (Acrocephalus phragmitis), and later on almost 

 invariably with the Eeed -Warbler (A. streperus). In the latter 

 case I have often found it in nests supported only by tall grasses, 

 and it seems remarkable that the Cuckoo is able to balance her- 

 self on such slight support sufficiently to place the egg in deep 

 cup-shaped nests. I believe that each female Cuckoo, with her 

 several husbands, occupies a certain area of country (varying in 

 size according to the number of birds in the district), into which 

 no other hen bird intrudes, and that all eggs laid by one bird are 

 of similar type. The nest in which the egg is to be deposited is 

 selected beforehand, and the egg is then laid on the ground near 

 at hand, and carried by the Cuckoo in its gullet, and placed in 

 the nest. As some days elapse between the laying of each egg, 

 it may well be that the bird notes the coloration of her first egg, 

 and spends the few days' interval before the laying of the next 

 one in searching for a foster-parent whose eggs are more or less 

 similar to her own. In support of this theory, I have found a 

 Cuckoo's egg, and always on searching farther in the same neigh- 

 bourhood have found others of exactly similar type. The follow- 

 ing day, perhaps in quite a different part of the country, another 

 Cuckoo's egg is found of quite a different variety to the previous 

 day's, and, searching on, more of these new type of egg are sure 

 to be found. I once thought that the Cuckoo always deposited 

 her egg with the same species of bird as had been her own 

 foster-parent, but that this is not so, I have proved by finding a 

 very distinct type of egg (white, lightly clouded, and blotched with 

 red) in the nest of the Whitethroat (Sylvia cinerea), and within 



