304 Wonders of the Bird World 



brown ; but the subject is worthy of further inquiry, for my 

 informant mentioned above knew nothing of the Cuckoo 

 laying blue eggs. Nor did I at the time — I am speaking 

 of thirty years ago — and Hedge- Sparrows and Pied Wag- 

 tails were the most frequent foster-parents in our neigh- 

 bourhood. It can well be, however, that blue eggs are 

 placed by the Cuckoo in Hedge-Sparrows' nests when the 

 opportunity arises, but are overlooked by those who do 

 not suspect that the bird ever lays a blue egg. The brown 

 eggs one generally finds may be laid by Cuckoos in whom 

 the production of eggs of this colour has become hereditary, 

 but which are at the moment unable to find a suitable nest, 

 with eggs resembling their own in colour and time of laying. 

 The most convincing evidence of the difference in pattern of 

 the egg laid by the female of our common Cuckoo may be 

 studied by any one who examines the series of eggs, with 

 those of the foster-parents, exhibited in the Natural 

 History Museum, and a remarkable confirmation of the 

 similarity of the Cuckoo's egg to that of the species which 

 it victimizes came under my own observation when I was 

 visiting my late friend, Mr. C. Bygrave Wharton, at his 

 house at Totton in the New Forest. He had observed a 

 female Cuckoo for some days frequenting his grounds, and 

 he was not long before he discovered a Sedge-Warbler's 

 nest with a Cuckoo's egg, which, but for its slightly larger 

 size, was an exact counterpart of the eggs of the Warbler, 

 even to the little black line which is seen on the eggs of 

 the latter. A few days later he found another Cuckoo's egg, 

 of the Sedge-Warbler type, laid in the nest of a totally 

 different bird, viz. the Reed-Bunting {Emberisa sckceniclus), 

 whose boldly-marked eggs are not in the least like those of 

 the Sedge-Warbler. We both drew the conclusion that 

 the Cuckoo which laid these two eggs always produced 

 eggs like those of the Sedge- Warbler, and that on the first 

 occasion she was fortunate enough to find a nest of the 



