APPRAISAL OF THE VARIOUS SPECIES 333 



weasel (M. cicognanii), skunk (Mephitis mephitis), raccoon (Procyon lotor), bobcat (Lynx 

 rufus), opossum (Didelphis virginiana), woodchuck (Marmola monax), red squirrel (Sciurus 

 hudsonicus), chipmunk (Tamias slriatusj, and mice. That other species, inhabiting the 

 Northeast but not encountered in this work, must also be included in this category is indi- 

 cated by the writings of other observers. Although citing no specific instance Eaton"' men- 

 tions the mink (Mustela vison) and marten (Martes americana). Seton^ reports the lynx 

 (Lynx canadensis) and fisher (Martes pennanti). The probability that wolves (Canis) take 

 grouse where the two occur together is corroborated by the findings of Skinner"" in the West. 

 Recently a case involving the porcupine (Erethizon dorsatum) has been published^. Un- 

 doubtedly the eastern panther (Felis couguar) formerly included the grouse in its diet, while 

 at the other extreme Allen'" has suggested that even shrews may menace young chicks. 



Where man's civilization has penetrated, the dog and house cat are added to the list. In 

 this connection Ewbank'^ makes the interesting statement that in North Carolina razorback 

 hogs destroy grouse nests. 



Among the birds have been identified the great horned owl (Bubo virginianus), barred 

 owl (Strix varia), goshawk (Astur atricapiUus) , Cooper's hawk ( Accipter cooperi), sharp- 

 shinned hawk (Accipter velox) and crow (Corvus brachyrhynchos). Then too a few instances 

 have been observed in which pheasants ( Phasianus colchicus) have caused nesting failure by 

 laying their eggs in grouse nests. Beyond these, various authors have noted a number of 

 others. Thus Audubon"' reported the raven (Corvus coraxj. Forbush"* and Eaton"" the duck 

 hawk (Falco peregrinus), McAtee''^ the red-tailed hawk ( Buleo borealis), marsh hawk (Circus 

 hudsonius) and even one instance involving the broad-winged hawk (Buleo plalypterus), 

 Hersey'"* the red-shouldered hawk (Buleo linealus), and Kipley"' the osprey (Pandion hali- 

 aetus). Applying only by inference to the eastern race, Patton ''" states that grouse in the 

 Black Hills of South Dakota are preyed upon by the Richardson's pigeon hawk (Falco co- 

 lumbarius). Gross'" has added two records for the snowy owl fNyctea nyctea) and Sutton"' 

 one for the screech owl (Otus asio). Undoubtedly several of the rarer species in this region 

 such as the golden eagle (Aquila chrysaelos), gyrfalcons (Falco rusticolus) and the great gray 

 owl (Scotiaptex nebulosa) should also be included but data are lacking and their signifi- 

 cance is negligible. 



Finally a number of cases of nest robbing have been traced to the northern blacksnake 

 (Coluber constrictor). 



Relationships During Each Life Period 



The foregoing is a rather imposing array. Yet only a few exert any appreciable influence 

 on grouse populations, especially in sections where the latter are hunted extensively for sport. 

 Furthermore, even among those species which are important, some are primarily effective 

 in breaking up nests, others as predators of chicks and so on. The records of the Investigation 

 indicate these relationships quite clearly for New York*. 



To what extent these data may be distorted by instances in which the victim was dead when 

 found by the predator or "on its last legs" is often difficult to judge. Such a relationship 

 certainly does not apply to nests. It probably occurs most frequently among chicks. With 

 respect to adults, as has been discussed'^, circumstantial evidence by the process of elimination 

 strongly indicates that in the majority of cases predation has been the original decimating 

 agent. 



* The basis for diagnosing the species responsible for broken-up nests and birds found dead is described in the Appendix, p. 709. 

 A See discussion of Role of Predation Durin[j Adult Period, p. 318. 



