HOW BIRDS MAKE THEMSELVES USEFUL 273 
stands this way: many hawks are killed every year for Hen 
Hawks that are not Hen Hawks at all; and even those that 
do properly bear this name take high rank as public bene- 
factors. 
We have a few other Hawks and one Owl whose bad deeds 
may almost balance their good ones, but they are rare in our 
northwestern states. Most of them belong to wooded re- 
gions. We may lay down the general principle that the birds 
of prey dangerous to poultry are not prairie species. 
Swainson’s Hawk, and Grasshoppers. — As an example 
of the beneficent work of Hawks let us take Swainson’s Hawk, 
one of the two-most common on our prairies. He feeds upon 
insects and small mammals, chief among which are grass- 
hoppers and gophers. He specializes in grasshoppers. As 
many as 130 of these insects have been found in his stomach 
after a single meal. If there were a hundred of these birds 
to the township, each eating 200 grasshoppers a day for a 
period of 120 days, then there would be 2,400,000 dead grass- 
hoppers to their credit in that town, which, at 15.4 grains 
apiece, would weigh 2.64 tons. Now, a grasshopper, alive 
and with normal appetite, eats its own weight in produce 
every day; that is, the 2,400,000 hoppers would eat 2.64 tons 
a day. Assuming that on the average their foraging season 
is shortened by 60 days, we save 158.4 tons of produce that 
they would have eaten. ; 
The Marsh Hawk and the Gophers. — Thousands of dollars 
have been spent in these states for strychnine and in bounties 
for gophers. Now, many of our Hawks and Owls wage a 
continuous warfare upon gophers or ground squirrels. The 
Marsh Hawk is a good example of these. He is the other of 
the two commonest Hawks on our prairies. A gopher a day 
would, of course, be a very stingy ration to allow him, but if 
