CHANGE OF HABITS IN ANIMALS 411 



carnivorous diet does not seem to have been the usual one. It 

 is true that the abundance of the Colorado Beetle induced 

 that handsome American finch, the Rose-breasted Grosbeak 

 (Guiraca hidoviciana] to give up its staple food of berries 

 for easier gluttony upon the Beetle, with the result that 

 superabundance of food led to the increase in numbers of 

 this as*of other birds in the Eastern States. But this is not 

 the rule, at any rate in our own country. Here the tendency 

 is distinctly that insectivorous birds should develop vege- 

 tarian leanings, a change of habit to be traced to the plenteous 

 variety of the offerings of field and garden. 



Fruit crops have had a predominating influence in this 

 respect, for such insectivorous birds as Blackbirds, Thrushes 

 and Starlings become more and more the pests of orchard 

 and garden, finding in gooseberries, currants, strawberries 

 and plums a diet which satisfies at one and the same time, 

 their need for food and drink. Yet the change of habit has 

 not developed to an equal extent in all these birds, for though 

 Blackbirds and Thrushes are equally destructive in dry sea- 

 sons, in wet seasons when moisture is plentiful, the Thrush is 

 more content to follow its natural pursuit of worms and slugs 

 while the call of ripe fruit seems always to appeal to its dusky 

 relative. Even Wasps have learned to give up their hunt for 

 Greenflies and other insects when plums are at the ripening. 

 At Hilston in Cornwall the common Red Squirrel has re- 

 cently adopted the fruit habit. Here the Squirrel used to be 

 a rare creature, according to a correspondent of The Field, 

 but in the few years before 1913 it increased rapidly in num- 

 bers till it could be counted by the score. In 1913 it began 

 to enter gardens, tearing the nets to get at strawberries ; from 

 these it passed in succession to raspberries and ripe plums, 

 till it finally attacked hard green peas, when the patience 

 of the gardener giving out, a warfare of extermination was 

 begun. 



Field crops also have proved a temptation to many a 

 bird. The attraction of potatoes for the Rook is an old story, 

 but its raids on grain are by no means negligible, as the 

 contents of its crop too often show. One would scarcely 

 expect Wild Ducks to be induced to forsake the worms and 

 insects of the marsh for the produce of the fields, yet in the 

 Tweed valley on autumn evenings numbers of Mallard visit 



