476 THE CUCKOO 



again found outside. 1 On rare occasions both cuckoos have been 

 found growing up side by side in the nest. In these cases it may 

 have happened that neither was able to eject the other. 2 On one 

 occasion two fully fledged young cuckoos were seen in the act of being 

 fed by one and the same meadow-pipit, a fact which points to their 

 having been reared in the same nest. 3 The presence of two young 

 cuckoos in the same nest is assumed to be the result of laying by two 

 different females, for when the eggs are found they almost invariably 

 prove to be of distinct types, and it is practically certain that those 

 laid by any given female are of the same type. 4 Rarely three eggs are 

 found. 5 Adolf Walter found three in a wren's nest twice in one week, 

 and ascribed this to the decrease of wrens and the increase of cuckoos 

 in the district. 6 



Sometimes, when the young cuckoo is hatched after the offspring 

 of the foster-parent, it finds them too big to eject. At least eight such 

 cases have been recorded, one by Buffbn, who found a young cuckoo 

 in a nest with two nearly fledged thrushes. 7 Probably ejection is 

 occasionally impossible when the cuckoo is born in a hole-nest. 



Among the questions arising out of the ejection of eggs or nest- 

 lings by the young cuckoo which still await a definite answer, is that 

 of the stimulus which moves the cuckoo to action. What causes this 

 blind and seemingly helpless creature to initiate and perform a singu- 

 larly difficult feat keeping the victim on its back while it scrambles 

 backward up the inside of the nest, jerking the burden off without 

 losing its own balance requiring a degree of strength that seems 



1 Quoted by A. H. Japp, Our Common Cuckoo, p. 47. See also Zoologisches Garten, 1868 

 (Adolf Mtiller) ; and Macgillivray, Hist, of Birds, iii. 109 (quoting from Weir). 



2 Zoologist, 1865, 9628 (E. T. Gunn) ; Magazine of Natural History, viii. 287 (H. Turner). 



3 British Birds, iii. 164 (E. A. Wallis). 



4 See on pp. 496-97. For the evidence see Link, op. tit., pp 146-49; Coward, Fauna of 

 Cheshire, i. 268. 



6 Link, op. cit., p. 150, quoting from the Journal fur Omithologie, 1874, 80 (H. Thiele), and 

 Ornith. Monateschrift, 1893,464 ; Zoologist, 1886, 368 ; 1906, 276 (J. G. Tuck) : Country Life, June 

 16, 1906 (A. C. Elwes), with photo of a hedge-sparrow's nest, containing three cuckoo's and 

 four hedge-sparrow's eggs ; British Birds, i. 325. Mr. Jourdain tells me there is also a robin's 

 nest with three eggs of C. canorus in the Hungarian National Museum. See also pp. 497-98. 



* Link, loc. cit. 



7 Link, op. cit., pp. 172, 174 (six cases) ; Field, 1900, xcv. 771, 949 (two cases). 



