BRITISH WARBLERS 



been the case, since the young were but a few hours old and 

 required the care and assistance of a parent for some weeks. 

 The approach of a member of another species is sometimes the 

 signal for an outburst of excitement, and may result in a 

 spirited attack upon the intruder. Of no bird is the approach 

 so much resented as that of the Cuckoo, and so long as it 

 remains in the neighbourhood of the nest the excitement, 

 of the male especially, knows no bounds. If it happens to 

 pass amongst the trees above the nest the male follows in 

 pursuit, uttering a curious jumble of sounds intermingled with 

 which are parts of his song, and upon his return moves 

 uneasily from bush to bush, expressing his excitement by 

 jerking, fluttering, spreading, and waving his wings, and at 

 the same time fully expanding his tail. His attitude at such 

 a time differs only in degree from that during sexual activity, the 

 wings being more fully expanded and the tail fanned out instead 

 of being slightly spread. It is curious that in the case of both 

 the "Willow Warbler and the Chiff-chaff there should be such 

 resentment shown at the presence of a Cuckoo, and interesting 

 also that the resultant expression of the emotion should be 

 identical. If these two species were especially singled out by 

 the Cuckoo as foster-parents for its young we could better 

 understand their behaviour, but according to my experience 

 this is not the case. 



Of the two the female is the more timid. She it is who is 

 suspicious when one approaches the nest, fluttering around 

 for some time before she can gain sufficient courage to 

 enter. The male is not so easily perturbed ; he may hesitate 

 before he carries food to his young and performs the necessary 

 duties, but it is not for long. The female often finds courage 

 in following in his wake, and therefore enters the nest imme- 

 diately after, if not at the same time with him. She, however, 

 shows all the while by her actions that her suspicions are not 

 allayed, casting frequent hurried glances this way or that. 

 The young remain in the nest about eleven days. For the 

 first few days the female spends much of her time brooding, 



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