453 



Letters, Extracts, and Notes. 



[Ibis, 



XXIV. — Letters, Extracts, and Notes. 



Cuckoos' Eggs. 



Sir, — Will you allow me to make one or two remarks on 

 Major Meiklejolin's very interesting paper on the "Breeding- 

 habits of the Cuckoo^' in ' The Ibis.' In ' Wild Life ' (vol. i. 

 no. 5, May 1913) some data were published by E. Pettit. 

 I have plotted a cui've of some of Mr. Pettit's I'ecords (a liberty 

 I hope he will pardon). The figures relate to the occurrence 

 of Cuckoos in Reed- Warblers' nests, and the abscissae refer 



12 3 4 5 



The occurrence of Cuckoos' egga in nests of the "Reed- Warbler 

 recorded by E. Pettit, in ' Wild Life,' May 1913. 



The abscissae = number of eggs in foster clutch. In each case 

 there was only one Cuckoo's egg in nest. 



to the number of foster eggs. The high mode may probably 

 be accounted for, as the normal clutch of a Reed-Warbler's 

 nest is four, by the Cuckoo ejecting one of the foster 

 eggs. It is more difficult to explain the "shelf between 

 1 and 2, as if the matter were due simply to chance, and the 

 Cuckoo's custom was to throw out a foster egg when she 

 deposited her own, the curve ought to rise gradually to 

 the mode. The rise between and 1 looks as if the Cuckoo 



