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 effectual 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. 
With this brief glance at the reasons for the decrease of 
birds, and this enumeration of the natural enemies which 
serve to regulate the increase in the numbers of birds, we 
may now turn to the problem of bird protection. 
