322 AUTUMN AND WINTER 



slums develop a taste for pickles. Indeed, birds very rapidly 

 change their feeding habits if there is pressure. They will 

 imitate, too, an individual who may show some morbid taste. 

 Little colonies of rooks, as of brown squirrels, may turn into 

 eaters of carrion. 



It is curious that more is not known of the food of birds 

 since classification began on the lines of the dietary. For as 

 birds feed, so are their beaks shaped ; nor is there any part 

 of the bird which has been so affected by locality and habit. 

 Compare the spillikin beak of the wren with the pearl pincers 

 of the hawfinch, or the aquiline hawk with the rook, or the 



HAWFINCH 



broad-based mouth of the nightjar with the awl of the wood- 

 pecker. In all these, and yet more clearly in the snipe and 

 avocet, you could infer the feeding habits a priori. But the 

 knowledge lacks precision as the aviculturists or keepers of 

 captive birds have realised. Few field observers care to be 

 aviculturists, but they are inferior to the keeper of caged 

 birds in this department of knowledge. 



We may be sure that the country would be overrun with 

 certain weeds if many birds did not live principally on seeds. 

 A type of the insect feeder is the goldfinch ; and once again, 

 after the lovely bird has nearly vanished, we begin to see 

 their flocks swarming among the thistles. They become 

 again part of the autumn landscape. Less conspicuously, 

 but as surely, the other finches, the buntings, and our one 

 warbler, the hedge-sparrow, are at work in thinning the 



