CHECKS UPON INCREASE OF USEFUL BIRDS. 371 



Other Bird Enemies. 



Some Gulls and the larger Grackles or Crow Blackbirds 

 are accused, with some justice, of nest robbing. There 

 seems to be little satisfactory evidence against the Cuckoos, 

 except the general aversion shown toward them by other 

 birds. 



Probably individuals of many species occasionally eat the 

 eggs of other birds or molest their nests, as do the Wrens. 

 Since we have acquitted the Catbird of the charge of robbing 

 birds' nests, it is only fair to state that John Burroughs writes 

 that he saw a Catbird in the act. Still, we cannot conclude 

 that this is a common habit with the Catbird ; it is probably 

 exceptional, as with the Oriole. While all the smaller birds 

 have their quarrels, it is not probable that many of them 

 seriously molest other species. 



REPTILIAN ENEMIES. 



All the common snakes, except, perhaps, the little green 

 snake, eat birds and eggs. Birds exhibit great dread of 

 snakes, but the Brown Thrasher or the Catbird will attack 

 them bravely in defence of their young. Some birds seem 

 to be incapacitated by terror when a snake appears at the 

 nest, and are rendered incapable of any eftectual defence. 

 The common black snake is the greatest enemy the birds 

 have among native Ophidians, for it climbs trees with the 

 greatest ease, and is so swift that it is able to catch young 

 birds when they first leave the nest ; and sometimes it strikes 

 down an anxious parent. 



FISH. 



Large trout, bass, pickerel, or pike occasionally catch young 

 birds that fall into the water, and young water birds while 

 swimming are often in danger from them. Older birds learn 

 to avoid the rush of the fish. I have seen a Grebe spring 

 into the air to escape a pickerel that darted at its feet. 

 Snapping turtles catch many small ducklings and large frogs 

 occasionally get them. 



With this enumeration of the natural enemies which serve 

 to regulate the numbers of birds, we may now turn to the 

 problem of bird protection. 



