ECONOMIC RELATIONS OF OUR BIRDS. 
443 
The most difficult and intricate problem of economic ornithology is that of 
the food of birds. In the discussion of tliis question it will be most convenient 
to bring that which birds eat under the two lieads, (1) Verjetation and Vegetable 
Matter, and (2) Animals and Animal Matter. The food of birds thus grouped 
must be further identified as belonging to one or tlie other of the following 
classes: 
(1) That, the consumption of which is, on the whole, a service to man. 
(2) That, the consumption of lohieh is, on the whole, an injury to man. 
To determine what birds do, or may under forced conditions, eat is certainly 
a very difficult question, and many of the problems which must be solved before 
their food can be properly classified as indicated embrace the extreme of 
intricacy. That this classification must be made before final conclusions can 
be reached, I think aU will agree; that sucli a classification can ever be made 
complete and unquestionable, there are gi-ave reasons for doubting; but that a 
desirable approximation to completeness is possible, we may feel confident. 
So much is yet to be learned in regard to the real and potential industrial 
relations of the plants and animals affected by birds, that whatever may now 
be said upon tlie subject must be regarded as open to modification by more 
detailed and careful future work. 
Beneficial services on the part of birds may be stated under the following 
propositions: 
(1) A bird renders a service when it is injurious or destructive to plants which 
are to be regarded detrimental. This may occur when the bird consumes the 
foliage, buds, inner bark, blossoms or seeds of injurious plants. 
The principal service which our birds render in this direction is in the con¬ 
sumption of the seeds of weeds; and the number which they destroy in the 
course of a season is very great. From the stomach and crop of one Carolina 
Dove were taken 4,016 seeds of the common pigeon grass, Setaria glauca. The 
service which a bird renders in this line, however, is not to be regarded as always 
proportionate to the number of seeds which it consumes, for the mere act of 
cultivation, necessary to many crops, so effectually controls these weeds that 
but little work is left for birds to do. Birds, therefore, which possess many very 
serious traits, and have only the habit of feeding upon the seeds of weeds in 
their favor, must be looked upon as of doubtful utility. 
(2; A bird renders a service when it feeds upon injurious mammals. Squir¬ 
rels, gophers, rats, mice, and hares are the principal ones, regarded as noxious, 
which are preyed upon by our birds. They are among the smallest, the 
most prolific, and the most destructive of mammals. All of them are largely 
herbivorous or frugivorous, but some of them are somewhat carnivorous. 
All are familiar with the havoc which rats often make among young chick¬ 
ens and ducks. The ground squirrels are said to feed occasionally upon 
insects and upon mice. Occasionally, at least, the little red squirrel plunders 
birds' nests of their eggs. In June of 1878, as Prof. W. A. Kellerman and myself 
were passing through the cemetery at Ithaca, N. Y., our attention was attracted 
to an evergreen, standing near the walk, by a pair of Robins, which were dash¬ 
ing wildly about among its branches. On examining the tree, the nest of the 
birds was discovered, and just below it sat a Chickaree eating one of the Robin’s 
eggs. 
An instance similar to the above is mentioned by Edgar A. Mearns, in the 
Bulletin of the Essex Institute, Vol. X, 1878. He says: “Among the Robin’s 
worst enemies may be ranked the red squirrels fSciurius hudsoniusj, for, though 
their young are subject to the attacks of Crows, Jays, and particularly to the rav- 
