140 Mr. C. F. M. Swynnerton on Rejections [Ibis, 



the ejection of the substitute being followed by a decision to 

 remove the eggs from a nest that had been detected; but it 

 did not seem that this occurred in a larger proportion of 

 cases than I found amongst nests on which I did not experi- 

 ment, and in some cases the damage to the nest suggested 

 that an enemy was responsible. Mr. Stuart Baker has men- 

 tioned an instance (' Ibis/ 1913, p. 398) in which all the 

 eggs were smashed, " evidently by a bird's bill " — a case in 

 which it seemed " as if the Shrike, in a fury at the deception 

 attempted on it, had itself broken the Cuckoo's as well as 

 its own e^^^.'^ I obtained no such instance myself, and 

 Lanius humeralis, on which I experimented several times, 

 was one of the birds that most tended, apparently , to remove 

 its eggs after two or three attempts at cuckolding, but 

 Mr. Baker's suggested explanation is quite likely correct. 

 Similarly, the fact that I obtained no instance of desertion 

 of the bird's own egg except in Bradyornis does not tell 

 against his supposition that the deserted nests he found 

 containing Cuckoos' eggs were deserted on account of the 

 latter's presence, though this naturally requires a little 

 proof unless such nests were proportionately more nume- 

 rous than deserted nests of the same species i^Horornis, 

 Garrulaxy Mesia, Liothrix, Anthus, Lanius, Swga, Cisticola) 

 not containing Cuckoos' eggs. I remember well that as a 

 school-boy in Ireland and England my main fear, justified 

 by experience, was lest by visiting a nest too frequently 

 or taking too many eggs I might make the bird desert. 

 Here, in Africa, my fear is not so much the desertion 

 of the eggs (though this sometimes occurs) as their disap- 

 pearance, and the Kafirs, in giving their reason for avoiding 

 tampering with a nest with eggs, or placing a charm in it 

 if they have touched an e^^, always say, not that the bird 

 will desert, but that it will take its eygs away ; cases are 

 sometimes mentioned in which, as in the case I have myself 

 mentioned above, the bird was seen carrying its eggs away. 

 I am inclined to suspect that there really is some difference 

 here, of a general nature, between the birds of the two 

 countries, conceivably in relation to different dominant 



