XXXV111 
INTRODUCTION 
acli contents of birds shot. When these cannot be determined with¬ 
out microscopes and collections of insects and seeds for comparison, 
the stomachs should be sent for examination to Professor F. E. L. 
Beal, of the Biological Survey, Department of Agriculture, Wash¬ 
ington, D. C. 1 In general it may be said that the thousands of 
stomachs which have already been examined have shown that birds 
are divided into three classes, — 
1. Those that are injurious at all times, as the three accipitrine 
hawks, which live mainly on small birds, game, and poultry. 
2. Those that are injurious part of the year and beneficial the 
rest of the time, such as blackbirds that come in hordes in the fall 
and destroy the crops, but which when scattered out over the coun¬ 
try at other times of the year do an immense amount of good by de¬ 
stroying injurious insects. 
3. Those that are beneficial at all times, as many hawks and owls 
and a large number of insectivorous and weed-seed-eating birds. 
As Professor Beal says: “ If crows or blackbirds are seen in num¬ 
bers about cornfields, or if woodpeckers are noticed at work in an 
orchard, it is perhaps not surprising that they are accused of doing 
harm. Careful investigation, however, often shows that they are 
actually destroying noxious insects; and also that even those which 
do harm at one season may compensate for it by eating noxious 
species at another. Insects are eaten at all times by the majority of 
land birds, and during the breeding season most kinds subsist largely 
and rear their young exclusively on this food. When insects are 
unusually plentiful, they are eaten by many birds which do not 
ordinarily touch them. Even birds of prey resort to this diet, and 
when insects are more easily obtained than other fare, the smaller 
hawks and owls live on them almost entirely. This was well illus¬ 
trated during the recent plague of Rocky Mountain locusts in the 
western states, when it was found that locusts were eaten by nearly 
every bird in the region, and that they formed almost the entire 
food of a large majority of the species.” 2 
1 The Survey will furnish, on application, blank schedules for recording data, tags 
for numbering the stomachs, and franked envelopes for mailing. When collected, the 
stomachs (crops and gizzards) should be placed in alcohol or formalin for at least a 
week. Before forwarding to the department, they should be taken from the fluid, spread 
out on a newspaper, and dried fbr several hours, then placed in a baking powder can or 
cigar box, wrapped with a franked envelope on the outside, and mailed. The collector 
will be reimbursed for the outlay for alcohol, and will receive five cents apiece for a 
limited number of stomachs of certain species. 
2 Beal, F. E. L., “ Some Common Birds in their Relation to Agriculture,” Farmer's 
Bulletin, No. 54, U. S. Department of Agriculture. 
