CHECKS UPON INCREASE OF USEFUL BIRDS. 355 



some States farther west, and that they are not numerous 

 enough to fully control the insects on which they feed. 



It is certainly desirable, then, to take measures to increase 

 the number of useful birds, and any inexpensive means of 

 accomplishing this end is worthy the most careful consider- 

 ation of thoughtful people. 



When one is asked what controls the numbers of birds, 

 he finds himself at a loss for a ready answer. There are 

 many well-understood checks upon their increase ; others 

 are more obscure. "We can understand, for example, why 

 the larger game birds and shore birds have decreased in 

 numbers ; but it is difficult to see why the Dickcissel or 

 Black-throated Bunting has disappeared from the Atlantic 

 seaboard and is now seldom found east of the Alleghanies, 

 why the Bed-headed Woodpecker has so nearly disappeared 

 from Massachusetts, or why certain resident species as well 

 as certain migratory species are common one season and 

 uncommon the next. 



To effectually protect birds we must first understand the 

 chief causes of mortality among them. Comparatively few 

 wild birds die from disease or old age. Most of them per- 

 ish from lack of food, the severity of the elements, or the at- 

 tacks of their enemies. The destruction of birds by storms, 

 great and widespread as it is, probably never occurs over 

 regions extensive enough to utterly exterminate any species. 

 Their destruction by starvation and cold is usually coextensive 

 onlv with the area of severest storm. Under normal condi- 

 tions the decimated species usually repopulate the country in 

 a few years. Many young birds are killed by storms in the 

 nesting season. Many migrating birds are blown into the 

 sea and drowned. Fortunately for the birds, they are ordi- 

 narily enabled by migration to avoid the severity of winter ; 

 but they are unable in this way to escape the destructive 

 agencies set at work by man along their lines of migration. 

 In annual, perennial, widespread, and complete bird destruc- 

 tion, man takes the lead among all other forces of nature. 



1905; and as copies of this report The Decrease of Certain Birds and its 

 Causes ; with Suggestions for Bird Protection can he obtained of the secretary 

 of the Board at the State House, its conclusions will not he reiterated here. 



