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28 ALLEN'S NATURALIST'S LIBRARY 



some time doubted in England, though well-known in Ger 

 many ; but the question was set at rest by two English orni- 

 thologists, Mr, Henry Seebohm and Mr. H. J. Elwes who, were 

 collecting together in Holland, and who received a nest of 

 Redstart's eggs, one of which, larger than the rest, was said t 

 be that of a Cuckoo. The eggs proved to be hard-set, wit 

 well-formed young inside They were alike blue in colou 

 but on trying to blow the larger egg, the foot of the little bird 

 a zygodactyle foot protruded from the hole, and effect- 

 ually proved that the tiny occupant was a veritable Cuckoo. 



In England the most common victims are the Pied Wagtai 

 the Reed- Warbler, and the Meadow Pipit ; and in each case 

 there is a remarkable similarity in colouring of the Cuckoo'; 

 egg to that of the foster-parent which she selects. It is su 

 posed that the coloration of the Cuckoo's egg is an heredita 

 faculty, and that each female Cuckoo lays a particular type 

 egg. This is in all probability the case, and Cuckoos whi 

 lay blue eggs come of a stock which has been hatched fro 

 blue eggs, and will continue to lay them, and deposit them 

 the nest of some blue-egg-laying species. 



Among the various types of Cuckoo's eggs in the collectio 

 of the British Museum are many which are exact copies of t 

 eggs of other birds. In some instances the likeness is truly 

 markable, and it is curious to see the large egg lying in the n 

 by the side of the smaller ones of the rightful parent, precisely 

 similar in colour, but double the size, looking in fact, like a 

 double-yolked egg of the species. In the above-named collec- 

 tion are Cuckoo's eggs showing the exact colour and markings 

 of the eggs of the birds victimised by the parasitic bird Pied 

 Wagtail's, Yellow Wagtail's, Blue-headed Wagtail's, Meadow- 

 Pipit's, Tree-Pipit's, Skylark's, Chaffinch's, Reed-Warbler's, 

 Sedge- Warbler's, Orphean Warbler's, c. But these eggs are 

 not always deposited in the nests of the species where the eggs 

 of the foster-parent exactly resemble those of the interloper. 

 In none of the Hedge-Sparrow's nests, for instance, have we a, 

 blue Cuckoo's egg, and it is curious to find an egg like that of 

 a Skylark or a Tree-Pipit deposited in the nest of a Marsh- 

 Warbler or a Chiff-chaff, the eggs of which are so differently 

 coloured that the sombre Cuckoo's egg lies in striking con- 

 trast, and it is wonderful that the little owners of the nest 

 do not detect the fraud. This dissimilarity in the colour of 



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