AVES 



259 



Similar striking facts are shown by Aughey's investiga- 

 tion during the outbreak of the Rocky Mountain locust, 

 when in a single year, 1874, they destroyed forty-five mil- 

 lions of dollars' worth of crops. For one meal, six robins 

 had eaten two hundred and sixty-five locusts; five catbirds, 



FIG. 296. A friend of the birds. 



one hundred and fifty-two; three bluebirds, sixty-seven; 

 nine chickadees, four hundred and eighty-one; twenty 

 swallows, five hundred and sixty-five: and eight flickers, 

 two hundred and fifty-two. Every species, of which there 

 were fifty present in that region, fed on the pests. Out- 

 breaks of army worms and field mice have also been checked 

 by the birds in a similar manner. 



The pupils of every school should determine whether 

 the number of birds is increasing or decreasing from year 



