28 atj,en'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 to 

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

 well-formed young inside They were alike blue in colour, 

 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 Wagtail, 

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

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

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

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

 faculty, and that each female Cuckoo lays a particular type of 

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

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

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

 the nest of some blue-egg-laying species. 



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

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

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

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

 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 eg- 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 o;' 



