78 USEFUL BIRDS. 
ment made by Childrey as to the assemblage of Owls when 
the field mice swarmed in Essex in 1580 received confirma-. 
tion during 1892. Local observers reported that, after the 
great increase of voles was noticed, the Short-eared Owl 
( Otus brachyotus) became much more numerous on the hill 
farms, and that many pairs, contrary to precedent, remained 
to breed. 
Dr. W. B. Wall expresses the opinion, from his experience 
with the pests, that their chief enemies are the Owl and the 
Kestrel (a Hawk), which do more to reduce their ranks than 
all the traps of the farmers and the “microbes of the scien- 
tists” combined. Both farmers and game keepers in England 
and Scotland are inclined to regard these birds as vermin, to 
be shot at sight. 
In some parts of the United States the destruction of the 
natural enemies of rodents by man has been so complete that 
these animals have greatly increased in numbers. Prairie 
hares, or Jack rabbits, as they are called, became so numer- 
ous in some States at times that they could not be kept in 
check by ordinary hunting, and the people of whole town- 
ships congregated to drive them into great pens, where 
thousands were killed with clubs. Gophers or spermophiles 
have so increased in numbers that they have become pests. 
Farmers have been obliged to resort to extraordinary meas- 
ures to destroy them. In Montana such large sums were 
paid out in six months of 1887 in bounties for the destruc- 
tion of ground squirrels or gophers and prairie dogs, that 
a special session of the Legislature was called to repeal the 
law, lest it should bankrupt the State. 
In New England our common hares (miscalled rabbits) 
are kept in check in thickly settled regions by hunters; but 
the field mice, which are not subject to this check, have 
increased so rapidly in many localities that during the hard 
winters of 1903-04 and 1904-05 thousands of young fruit 
trees in the New England States were attacked by them and 
ruined. These mice have become so numerous that in some 
places young trees cannot be grown unless protected from 
them. They also destroy a great quantity of grass and grain, 
some small fruit, and vegetables. Unfortunately, the food 
habits of these little animals have never been fully studied. 
