CHECKS UPON INCREASE OF USEFUL BIRDS. 369 



of both Crow and Jay have been published elsewhere. 1 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 

 vincing 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 

 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 hot 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 larvae of the gipsy moth and other hairy eater- 



Fig. 155. — Blue Jay, one- 

 half natural size. 



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, Ibid., 1904, pp. 498- 

 502. 



