336 PRE DAT I ON 



sented the diagnoses of the specimens which have been attributed to predation. Besides these, 

 21 other specimens were picked up to which no cause of death could be ascribed, but which 

 it is probable were largely the result of predalion. 



In spite of the fact that only a small proportion of the chicks which are known to have 

 died were ever found, it seems unlikely that many were taken by predators not included here. 

 Furthermore, on both areas, the situation was similar year after year. It is fair to conclude, 

 therefore, that these records are representative. 



The data indicate that the most important species have been certain birds of prey. While, 

 except for a few cases, it has been impossible to determine the exact hawk or owl responsible, 

 field experience leaves little doubt that the Coojier's hawk and sharp-shinned hawk are out- 

 standing. Of the specimens referred to "hawk sp." nearly all were found on "killing logs" 

 of these hawks, amid the remains of warblers, thrushes and other woodland birds upon which 

 they regularly feed. 



In the group referred to "hawk or owl" — all from Connecticut Hill — the great horned owl 

 undoubtedly entered in. A considerable immber of chicks were also taken by the fox, but 

 whether this animal or the owl should rank higher it is impossible to say. As in the case of 

 nests both the red and the gray fox appear equally destructive. The one record of a crow 

 carrying off a young chick appears to have been very unusual. 



No definite evidence of predation on grouse chicks by other s|)ecies has been observed. 

 To be sure it has occurred to a minor degree and under different circumstances might be im- 

 portant. Certainly there can be little question that the goshawk takes a toll at this season 

 when the two occupy the same habitat. The raccoon, too, will readily kill prouse if given a 

 suitable opportunity, as was demonstrated at the Research Center when several females and 

 their broods being held in natural enclosures were completely wiped out by this animal. The 

 same may be said for ihe weasel. While losses from house cats have not been encountered 

 this animal is undoubtedly a factor where it is more frequent in grouse habitats. 



On the Connecticut Hill study area in particular the red-tailed hawk, red-shouldered hawk 

 and marsh hawk have been common. Yet no instances of their molesting grouse have been 

 recorded during the Investigation. As their food habits sihow* their principal diet consists 

 of mice and other forms chiefly found in open land types. Quite probably they occasionally 

 secure a grouse chick, as for example the red-shouldered hawk examined by Hersey"". But 

 in any event one may conclude that the effect of these species on brood survival is negli- 

 gible. Similarly the broad-winged hawk, although the commonest one on the Adirondack 

 area, was never associated with grouse mortality. 



Adult Period 



During the adult period a considerable loss from predation is customary each year, taking 

 place chiefly in late winter and spring. The remains of a much larger proportion of these 

 birds have been subsequently picked up by the Investigation's field crews than in the case 

 of chicks. Analysis of this material, while obviously far from precise, nevertheless affords 

 valuable data on relative predator importance not otherwise obtainable. Of the 1,174 speci- 

 mens examined 550 have been undeterminable as to cause of death. The proportion of such 

 records, however, has been qiiilc similar throughout the study, both fnmi year to year and 

 seasonally. Those it has been possible to analyze have, therefore, been considered represen- 

 tative. The diagnoses of those ascribed to predation are presented in the following table. 



• See ditcuMinn of KimmI Hibili in New Yurk. p. 343. 



