42 



they well realized the danger, and were determined to conquer 

 or die. The gray squirrels are not so active as the reds; but 

 either of them are likely, when opportunity offers, to eat birds' 

 eggs or kill the young. Mr. F. H. Mosher writes me from 

 Hyde Park, N. Y., that the squirrels there upset birds' nests 

 quite wantonly; also that they bite off the heads of young 

 birds and throw the bodies to the ground. It is difficult to 

 judge how universal such habits are among squirrels, but 

 where they are observed, it is safest to kill the squirrels at 

 once. 



I have dwelt at some length on the habits of the creatures 

 that contribute to restrain the increase of birds, that we may 

 fully realize the importance of protecting birds against these 

 enemies. If the smaller birds are to resume even their normal 

 numbers, a different policy must be pursued from that hereto- 

 fore adopted. Bird protection means something more than 

 the ordinary interpretation of the term. If we wish to protect 

 the smaller birds, we must banish or destroy any excess of 

 their natural enemies. How this is to be done, and just what 

 its effect will be if it succeeds, is the next subject for inquiry. 

 These questions can be answered only by the experience of 

 the future. 



The most important conclusion that has been confirmed 

 by these two years of bird study is that the Corvidce (crows 

 and jays) are very largely responsible for the decrease of the 

 smaller birds. I am well aware that some investigators will 

 not agree with this conclusion; but it has been forced upon 

 me by the experience of thirty years and the corroborative 

 observations of the last two. No one can doubt that in the great 

 plan of nature these birds fill well their place. Their useful- 

 ness as insect destroyers is well known; but where they become 

 too numerous, their supply of insect food is soon so limited 

 that they must turn to other sources for a good part of their 

 animal food; then small birds and young chickens suffer. 

 Could the crows and jays hold in check those insects that, in 

 consequence of the destruction of small birds, are allowed to 

 increase, then the destructive propensities of the crow family 

 need not be viewed with alarm. That they can do this is im- 



