274 POULTRY AND WILD BIRDS 
there are 100 of these Hawks to the township, living with us 
only 150 days during the season, they would dispose of 15,000 
gophers. 
The Owls will pass a similar examination. It is a well- 
known fact that they supplement the work of the Hawks, 
the latter hunting by day and the former in the dawn and 
twilight. 
All the Birds Together. — Of course, no bird confines itself 
to just a single article of food; but if we allow it a mixed diet 
of grasshoppers, crickets, beetles, gophers, mice, etc. we shall 
not diminish the value of its services. Nor is there just one 
kind of bird in a given area, but many kinds. Estimating 
one and one half birds to the acre, as is considered a fair aver- 
age, we have 34,560 to a township. If we allow each of these 
25 insects a day for a period of 150 days, they would dispose 
of 129,600,coo insects in a season. 
In fact, the work of the birds is so effective that the insects 
usually become pretty well cleaned out before the close of the 
summer, and the scarcity of their favorite food is the chief 
cause that drives the birds south in the fall. 
