1 88 BIRD BEHAVIOUR 



ties. The natives of Yarkand go further, and say 

 there are no male Cuckoos at all, the hens being 

 the paramours of a Shrike {Lanius isabellinus), the 

 Barred Warbler {Sylvia nisoria), or even of frogs ! 

 a belief which at any rate argues that two Cuckoos 

 are not often seen together. 



The egg, when incubated by the fosterer, develops 

 after a proportionately short incubation period 

 into a blind naked young bird which has a hollow 

 in the back, facilitating the work in which it almost 

 immediately engages of turning eggs or its foster- 

 neft-mates out of the nest by getting under them 

 and backing upwards to the edge of the nest till 

 they are rolled out. When, as rarely happens, two 

 Cuckoos' eggs have been deposited in the same 

 nest, the " survival of the fittest "_ is naturally not 

 determined till after a severe contest. But this 

 fury for eviction only lasts about a week, after 

 which time the young Cuckoo will tolerate a bed- 

 fellow. 



The foster-parents do not concern themselves 

 about this fratricidal behaviour in their nursery, 

 but assiduously feed their changeling and leave the 

 rightful heirs to die ; nor is there anything wonder- 

 ful in this behaviour, as it is the common custom 

 of birds to* neglect a fallen nestling and to give 

 most food to that which is most strongand ravenous. 

 I once had an opportunity of watching a nestful of 

 Starlings which were being reared on a roof just 

 under my window at Oxford ; and as far as I 

 could see there was not the least attempt at fair 



