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 live 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, larve, 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. 8. De- 
partment of Agziculture. 
