64 
of the skunk and the crow, which destroy the grouse eggs 
or young. Eagles and hawks kill game birds as well as 
other birds; but they also hold in check squirrels, crows, 
jays, weasels and other enemies of these birds. All this may 
he true of the hunter also; hut hawks, owls and foxes kill, 
in addition, field-mice, deer-mice and shrews, all of which 
might otherwise increase unduly, and become very destruc- 
tive to eggs and young birds. No one knows how often 
the nests of birds are broken up by deer-mice. They climb 
trees like squirrels, nest in hollow trees, and may be as 
great a danger to birds as is the dormouse of Europe. 
Shrews are notorious flesh-eaters, and possibly may be 
very destructive to ground-nesting birds ; while field-mice, 
when pushed for food, are among the most destructive rodents 
known. These creatures probably feed mainly at night ; their 
habits are not well known. They can be held in check by 
natural means only, hence we must beware of destroying the 
animals that feed on them. Acknowledging, as we must, that 
under natural conditions the natural enemies of birds are 
useful, there is no doubt that under the artificial conditions 
produced by man some of them may at times need artificial 
check. Under natural conditions, the crow is certainly a 
valuable force in nature; but when we have destroyed the 
raccoons, the larger hawks, owls and eagles, — the only crea- 
tures besides man, perhaps, which serve to hold the crow in 
check, — then we must also check the increase of the crow, 
or, increasing in numbers and wanting sufficient food, it will 
become very destructive to grain, fruit, fowls and smaller 
birds. In like manner we have destroyed the wolves, which 
formerly kept the fox in check ; we must then, check the fox, 
lest it, increasing, kill too many fowls, game and insectivorous 
birds. For this reason, it is well that the fox and crow are 
not protected by law. 
Partly because of the fact that the natural enemies of 
birds may sometimes need an artificial check, and partly be- 
cause the injury done by them is often much magnified, it 
seems best to publish here some evidence of their compara- 
tive harmfulness, under the conditions now prevailing in this 
Commonwealth. 
