444 
ECONOMIC RELATIONS OF OUR BIRDS. 
ages of the black snake (Rescaurion constrictorJ, yet none of these enemies in¬ 
flict as much injury as the squirrels,' because, not only do they seek out and 
. devour the eggs, but the young are also eaten; and their numbers are in excess. 
. . . On the morning in question, a red squirrel came a considerable distance 
out of the woods, ascended to this nest, and would have destroyed all the young 
ones had not the parent returned just at the critical moment.” The Rqbin suc¬ 
ceeded in driving the squirrel away, but not until one of her young had been 
eaten. 
In the spring of 1879 I placed the young of the Chipping Sparrow in the cage 
with a young pet flying squirrel fSciuropterus volucellaJ. The bird was seized 
with energy and killed but not eaten. 
How general this practice among squirrels may be I do not know; it suggests, 
however, that the little red squirrel and its nearer allies may be formidable 
enemies of nearly all our small woodland birds. 
The fact, too, that rats and ground squirrels are carnivorous, to some extent, 
suggests that these may be destructive to birds which nest upon the ground in 
fields and on the prairies. Mice are preyed upon to a considerable extent by some 
of the Hawks, and Owls, and probably also by the Sand-hill Crane, but whether 
birds of prey are especially serviceable in destroying squirrels and gophers may 
be questionable, 
(3) A bird does us a benefit when it feeds upon injurious birds. This head is 
introduced here, not because any of our birds are known at present to render a 
service in this direction, but because it suggests' a field in which further observa- 
tion is needed. 
(4) A bird assists us when it feeds upon injurious reptiles. Of the reptiles 
preyed upon by birds, our larger snakes are the only ones to be regarded as 
noxious. Snakes that are not venomous have been classed among beneficial 
animals, because they feed to some extent upon mice and insects. This classifi¬ 
cation, however, so far as it includes the larger species of snakes, appears to be, 
at present, unwarrantable. The fact that snakes also eat small birds and birds’ 
eggs, toads, frogs, salamanders, and some of them fish, is conclusive proof that 
they do some injury. "While my own observations indicate that both insects 
and mice are eaten by them, yet frogs and toads appear to form by far the larger 
part of their food, at least, that of our common garter snake. From the stomach 
of a large striped snake fEutainia sirtalisJ were taken eleven ground beetles, 
two elaters, one lamellicorn beetle, three caterpillars, one millipede, and one large 
toad. Leaving out of this account the toad, it will be seen that, in this particu¬ 
lar instance, the snake had done a greater injury than a service, for the ground 
beetles, usually regarded as beneficial, nearly double in number all the other 
insects combined. The fact that during the season when insects are abundant, 
snakes are often found with their stomachs entirely empty, suggests that, with 
some species, at least, insects are only make-shifts for food. It should be 
observed in this connection that all snakes are capable of enduring a long fast 
without apparently suffering any very great inconvenience. If, then, it is true 
that insects are only eaten in default of other food, the services of snakes in 
this direction must be much smaller than might otherwise be expected. 
Our frogs and toads in the adult stage, so far as is known, are entirely in¬ 
sectivorous, and are, Iherefoi-e, harmless, except so far as they may be destruc¬ 
tive to useful insects. Toads are nocturnal in their habits and feed upon the 
ground in gardens and fields where there are few animals, except the shrews 
and moles, to take their place. Some of the frogs, too, spend the summer in 
fields and meadows where birds are few, and consequently have a special work 
