1918.] by Birds of Eggs unlike their own. 137 



the ground with (it seemed) the weight of the egg. During 

 the last few yards of her flight she disappeared behind 

 tree-trunks, but I judged that she must have reached the 

 ground about fifty yards from the nest, which was about 

 twenty feet up. A careful search failed to recover the egg, 

 but it had been very visible in the bird's bill as he, or she, 

 .flew past within a few feet of myself. 



The occasional ejection by the Cuckoo of one of its 

 victim's eggs the day before it inserts its own, quoted by 

 Major Meiklejohn, would seem likely to lessen slightly its 

 chance of getting its own e^^ accepted ; but this is a point 

 yet to be tested. I think that on all the occasions on which 

 I brought the birds' eggs to their original number again 

 after an interval, it was by the return of their own egg. 

 This was never rejected unless its appearance had been 

 altered, and, of course, if the Cuckoo's harmonized well it 

 would not be rejected either. 



Against the suggestion conveyed by my results must be 

 placed cases such as that quoted by W. L. Sclater from Ivy 

 (' Fauna S. Africa,' Birds, iii. p. 198). Here a nest of 

 Andropadus importunus was found " containing two of the 

 usual eggs .... in addition to five large Cuckoos' eggs. 

 These all together more than filled the small cup-shaped 

 nest^ the rightful occupants of which " had apparently not 

 deserted. Such a case must be rare^ and could hardly 

 happen in the case of many foster-parents ; but from other 

 records it would seem that this Bulbul is quite the " Hedge- 

 Sparrow " of South Africa, in the sense of being readily 

 duped — a contrast to Passer arcuatus, the " Redstart " of 

 the same country. In any case more experiments are 

 needed. 



12. The number of rejections of unmatched eggs so very 

 greatly exceeded the acceptances that conclusions based on 

 the eggs found are likely often to be unreliable, especially 

 if elimination is not well allowed for. — Without having 

 recorded nearly all my experiments — a pity from this point 

 of view — I should say that rejection of the ill-matched 

 substitutes took place in about 80 per cent, of cases. This 



