CHECKS UPON INCREASE OF USEFUL BIRDS. 369 
of both Crow and Jay have been published elsewhere.’ The 
American Crow (Corvus americanus) is a most deadly enemy 
to birds from the size of the Chipping Sparrow to that of the 
Night Heron, Ruffed Grouse, and Black Duck, for it contin- 
ually steals the eggs and young of such birds and poultry. 
The evidence on this point is so con- 
vineing and voluminous that it is 
impossible to avoid this conclu- 
sion, although it is quite prob- 
able that only certain 
individual Crows are 
the criminals. Crows 
not only destroy eggs and 
young birds, but they have 
been known to band together 
to hunt down and kill adult birds 
as large as the Ruffed Grouse. 
The well-known Blue Jay 
(Cyanocitta cristata) is destructive 
to the eggs of the smaller birds, 
whose nests it robs systematically, 
and it has frequently been seen to 
kill the young. The Robin and other 
larger birds will drive the Jay away Pig. 165.— Blue Jay, one- 
from their nests, but it often succeeds 
in robbing them by stealth. Vireos, Warblers, and Spar- 
rows it regards very little, and plunders their nests without 
noticing their agonized cries. Jays and Crows together 
sometimes make it very difficult for other birds to raise any 
young. It would not be advisable to exterminate the Crow, 
for it has many useful habits; but it should not be allowed 
to increase at the expense of the smaller birds. Crows are 
valuable as grasshopper killers, and they are destructive to 
the gipsy moth. Jays eat the eggs of the tent caterpillar 
moth, and the larve of the gipsy moth and other hairy cater- 
1 See The Crow in Massachusetts, Annual Report of the Massachusetts State 
Board of Agriculture, 1896, pp. 285-289; Two Years with the Birds on a Farm, 
Ibid., 1902, pp. 147-149; and The Decrease of Certain Birds, [bid., 1904, pp. 498- 
502. : 
