168 CONSERVATION OF CANADIAN WILD LIFE 



Feeding Habits of Chief Groups. — It will be of interest to 

 review briefly the feeding habits of the chief groups of birds. 



Hawks and owls, which, as a group, are wrongly regarded 

 as noxious birds, prey not only upon injurious small mam- 

 mals, such as field-mice, gophers, and various rodents, but 

 also consume injurious insects. The little sparrow-hawk 

 lives largely upon grasshoppers and crickets, and such 

 larger hawks as Swainson's hawk hve almost exclusively 

 upon such insects in the summer-time. The noxious hawks 

 and owls (see p. 210), such as Cooper's hawk, the sharp- 

 shinned hawk, and the great horned owl, form a very small 

 proportion of the family. 



The thrush family, including such well-known birds as 

 the robin and bluebird, are not only well known but useful 

 birds. While robins are sometimes destructive to fruit, a 

 large portion of the vegetable matter they consume consists 

 of wild fruits; 330 stomachs contained 58 per cent vegetable 

 matter, of which 47 per cent consisted of wild fruits, and 4 

 per cent of cultivated fruits.* About two-thirds of the 

 food of the bluebird consists of insects, such as caterpillars, 

 grasshoppers, and beetles. 



The nuthatches, tits, and tree-creepers are among the most 

 diligent of hunters after insects in all their stages, partic- 

 ularly in the egg stage, and figures have already been given 

 to indicate the enormous destruction of insect life they 

 effect. The warblers constitute a family of almost purely 

 insectivorous birds that is well represented in Canada. 

 Wherever insects may be found some species of warbler 

 will also occur. Shyly they pursue their work of search- 

 ing every leaf and twig of shrub or tree for eggs, larvae, or 

 adults of destructive insects. We have found them to be 

 not unimportant factors in the control of certain pests of 



* Except where it is otherwise stated, these analyses of stomach contents 

 are taken from the publications of the Biological Survey of the U. S. De- 

 partment of Agriculture. 



