76 USEFUL BIRDS. 
Professor Aughey gathered statistics regarding the killing 
of Quail and Prairie Chickens for the market during this 
period, and concluded that in thirty counties the average 
yearly slaughter of these birds must have been at least five 
thousand Quail and ten thousand Prairie Chickens for each - 
county, or four hundred and fifty thousand birds in all. We 
can only conjecture as to how great was the destruction of 
other game birds. 
The poisoning of birds in the west permitted an increase 
of many other insects besides the locusts. A farmer from 
Wisconsin informed me that, the Blackbirds in his vicinity 
having been killed off, the white grubs increased in number 
and destroyed the grass roots, so that he lost four hundred 
dollars in one year from this cause. 
THE DESTRUCTION OF INJURIOUS MAMMALS BY BIRDS. 
The injury to trees and crops by insects is not the only 
evil that has followed the destruction of birds and other 
animals by man. Rapacious birds hold a chief place among 
the forces which are appointed to hold in check the gnawing 
mammals or rodents, which breed rapidly, and, unless kept 
within bounds, are very destructive to grass fields, crops, and 
trees. The great swarms of lemmings which have appeared 
from time to time upon the Scandinavian peninsula are his- 
torical. Their migrations, during which they destroy the 
grass or grain in their path, until finally they reach the sea 
and perish in a vain attempt to cross it, have been recorded 
often. A similar increase of rodents’ may take place any- 
where whenever their natural enemies are unduly reduced in 
numbers. Such cases are on record in England and Scot- 
land. In Stowe’s Chronicle, in 1581, it is stated : — 
About Hallontide last past (1580) in the marshes of Danessey Hun- 
dred, in a place called South Minster, in the county of Essex, there 
sodainlie appeared an infinite number of mice, which overwhelming the 
whole earth in the said marshes, did sheare and gnaw the grass by the 
rootes, spoyling and tainting the same with their venimous teeth in such 
sort, that the cattell which grazed thereon were smitten with a murraine 
and died thereof; which vermine by policie of man could not be de- 
stroyed, till at the last it came to pass that there flocked together such 
