470 THE CUCKOO 



cuckoo above referred to was seen to place her egg after laying it on 

 the ground in a rough nest previously prepared by her mate. Such 

 nests appear to be usually deserted by the owner, except, it is said, by 

 species like the wagtail, hedge-sparrow, robin, some warblers, which 

 are the most often victimised. 1 The cases in which they are not 

 deserted probably account for most of the relatively rare occasions 

 on which a cuckoo's egg is found together with a full clutch of the 

 owner, for the fact that the cuckoo laid first would probably save the 

 eggs of the other from ejection. It does sometimes happen, however, 

 that the cuckoo deposits her egg after the full clutch has been laid. 

 An instance is given of her doing so in a white- wagtail's nest, from 

 which, moreover, she ejected no eggs. Another cuckoo's egg, quite 

 fresh, was found in the nest of the same species, which contained four 

 of its own eggs at least ten days incubated. Similar instances could 

 be given. 2 



The nest which the cuckoo usually chooses is one in which there 

 are eggs that the owner has not begun to incubate, the reason given 

 being that she hesitates to drive an incubating bird off the nest. s 

 The reason is not, however, convincing, unless we assume that the 

 cuckoo has two or three nests in mind to select from when ready to 

 lay its egg, and that, finding an incubating bird on one, it would 

 then go to the next. Moreover, an instance, already noted (p. 467), 

 is given by Bailly from his personal observation of a cuckoo driving 

 a robin from its nest. He adds that he saw another cuckoo 

 drive a whinchat from its nest on the ground by swooping down 

 upon it 4 



The cuckoo's approach to a nest in which she intends to deposit 

 an egg is probably always actively resented by the rightful owners, if 

 present. A robin is recorded as having got hold of the trespasser by 

 the back of the neck, to which he hung for a few seconds with fierce 



1 J. A. Liuk, op. tit., p. 152. 



* J. A. Link, op. cit., pp. 154, 158, 158, 159 ; Naumann, Vvgel Mitteleuropas, iv. 405. 



' J. A. Link, op. cit., p. 158. 



4 Ornitholoyie de la Savoie, i. 387 (footnote). 



