Birds by Land and Sea 



thought that birds also have their moralities, and 

 that a craven spirit has been engendered in the 

 cuckoo by the consciousness of its crooked dealings 

 with its neighbours. 



Darwin (" Voyage of the Beagle," page 53) 

 quotes Prevost to the effect that the female has 

 to pair afresh after laying each egg or two eggs, 

 and argues that if the bird waited to sit until all 

 were laid, those first laid would probably addle ; 

 and that if it hatched each egg or two immediately 

 after laying, the time of its stay would be too 

 short. But Darwin himself has shown ("Origin 

 of Species," page 212) that the normally non- 

 parasitic American cuckoo has eggs and young 

 successively hatched in its nest, all at the same 

 time ; and it is well known that with regularly 

 nesting birds even the maternal instinct gives way 

 under the migratory impulse : witness the deserted 

 broods of the swallow tribe. 



- An instructive parallel is afforded by the parasitic 

 American cow-birds referred to in the same work 

 (page 215). Of the three species of cow-birds, one 

 sometimes pairs, sometimes lives promiscuously in 

 flocks. It either builds a nest of its own, or appro- 

 priates one belonging to another bird, ejecting the 

 young, sometimes even building a nest of its own 

 upon the nest so appropriated. It usually rears its 

 own young, but from the fact that the young of this 

 species has been seen to follow old birds of a dis- 

 tinct kind, it has been inferred that it is sometimes 



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