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The draining of meadows and marshes drives out the birds 
that frequent these places. Thousands of acres have been 
drained and made into cranberry bogs ; many swamps have 
been flowed for reservoirs ; swamps near cities are drained 
and filled. The extension of cities, the building of summer 
cottages along the coasts, and the increase of population 
generally, all tend to drive out the birds from their chosen 
haunts. The effect of these repellent agencies is to reduce 
the area of the region furnishing a food supply to the birds, 
and so, in the end, to decrease in the aggregate the number 
of birds. 
The Natural Enemies of Birds . 
In the opinion of many correspondents, the natural ene- 
mies of birds do no appreciable injury, while others consider 
them the chief cause of the decrease of birds. It is notice- 
able that some sportsmen and gunners complain particularly 
of hawks, foxes, crows, skunks and weasels. At first sight 
it might seem that those most responsible for the decrease of 
birds were trying to shift the blame ; but we must remember 
that those who are most in the woods with the birds are most 
likely to observe their destruction by their natural enemies. 
Under normal conditions, the natural enemies of birds are 
also their friends. There is no better proof of this than the 
statements made by the early settlers at a time when game 
birds were here in great abundance. Eagles, hawks and owls 
were then far more numerous than they are now. Evidently 
they produced no appreciable effect on the numbers of game 
birds. 
Hawks that feed on birds will overtake the crippled, sickly, 
least active or most conspicuous birds. This results in a 
survival of the wariest, strongest, most active and least con- 
spicuous individuals, — in a word, the fittest. It prevents 
the spread of disease and the propagation of weakness and 
unfitness; it preserves the race. This is true to a much less 
extent of the effect of shooting, for a charge of shot will over- 
take the strongest as well as the weakest, — the fit as well as 
the unfit. Hawks, owls, foxes and other enemies of birds 
also protect birds in another way. The horned owl, no doubt, 
now and then kills a grouse; but it also checks the increase 
