98 WHY CERTAIN BIRDS MOB OTHERS 



XIV 



Cuckoos are much in evidence on the moors just now. 

 certain * watclied a P air yesterday flying in circles after 

 Birds mob a somewhat unusual manner, apparently the 

 male pursuing his mate, or (as the unprincipled 

 habits of the cuckoo render rather more probable) some- 

 body else's mate. Ever and anon as they flew some little 

 bird or other here a lark, there a yellow bunting rose 

 out of the heather or the thorn bushes, and pursued the 

 cuckoos till they were clear of that quarter of the ground. 

 What is the impulse or fascination which makes small 

 birds act in this way ? If they recognise the cuckoo as 

 the enemy which furtively deposits in an alien nest an 

 egg containing a creature which will ultimately destroy 

 the legitimate brood, why do they betray the neighbour- 

 hood of their own nests by flying out in such vociferous 

 flurry ? If, on the other hand, they are deceived by the 

 hawk-like mien and flight of the cuckoo (I have myself 

 shot a cuckoo in mistake for a sparrow-hawk), surely the 

 instinct of self-preservation should prompt them to lie 

 low, but neither for cuckoo nor hawk will they do so. On 

 the contrary, they hang upon the enemy's skirts so long 

 as their power of flight enables them to do so. Their 

 hatred seems to overcome their discretion ; they are will- 

 ing to risk the sparrow-hawk's swoop for the gratification 

 of uttering their execration so near that he cannot fail to 

 hear it, and to be annoyed. 



I never could think of an explanation of the similar 

 manifestation of feeling by rooks towards herons, until 

 it occurred to me that possibly herons, in times when fish 

 and frogs are hard to come by, may conceive an un- 



