POPULATION CHARACTERISTICS 517 



relationship ma}' become. Tn any case, there seems small likelihood that, in years of increas- 

 ing or high abundance, variations in sex ratio exert a controlling effect on grouse populations. 

 Throughout the 13 years of the Investigation the proportion of breeding females on the areas 

 under observation has at no time been seriously reduced. Nevertheless, one must bear in 

 mind that a major period of grouse scarcity has not been experienced during this study. 



Grouse Densities 



Of interest also, to the sportsmen as well as the game manager, are the grouse population 

 levels which may be attained in various coverts. It is often next to impossible to appraise 

 adequately estimates of game abundance because they are not expressed in relation to some 

 definite standard of measurement. What one observer may judge a plentiful supply of birds, 

 another, with different experience, may consider only moderate. The data of the Investiga- 

 tion are, therefore, expressed in terms of the acreage involved. 



The ratio of population to covert area is the density of population. In tracts of extensive 

 forest, of which the Adirondack area is representative, the habitable range is usually the 

 same as the total land surface. In disconnected coverts, which constitute most of the more 

 heavily hunted grouse range in the Northeast, this is not true as only a part of the intervening 

 fields is appreciably used by these birds. As explained in Chapter III. grouse cover in such 

 localities has been considered to const^iute all woodland and lirush plus a 100- foot belt of the 

 adjacent open land. This strip, on Connecticut Hill, amounts to about 29 per cent of all of 

 this type present. 



Nest Densities 



As discussed in Chapter V. instances have often been observed where several grouse nested 

 in quite close proximity to one another. But, in dealing with population behavior, coverts 

 must be considered in their entirety. It has never been possible, however, to locate all the 

 nests on the study areas. On the otlicr hand, it is believed tluil ncarlv all the females present 

 in the spring have nested during most years*, although this jiruportion seems to have been 

 somewhat low on Connecticut Hill in 1935 and 1936. Therefore, the number of this sex 

 present during the breeding season represents a generally close approximation of nest density 

 (table 76). 



It is apparent that nests are normally more numerous within llic disconnected tracts of 

 grouse cover making up "woodlot" range than in extensive forest areas. This, of course, is 

 also true of the average abundance of grouse. Nevertheless, wide variations are common in 

 l)oth regions. 



With respect to individual coverts, the highest densities witnessed by the Investigation 

 occurred on certain units of Connecticut Hill in 1935, even though the breeding population 

 for the whole area was only the second highest observed. Just what levels were reached 

 cannot be determined precisely, however, because no means has been devised for accurately 

 judging the number of females failing to nest. The available evidence suggests that this 

 proportion may have been above average in that year. In any event at least seven or more 

 nests per 100 acres occurred on two units of 155 and 166 acres respectively, the number on 

 the latter perhaps having been nine or ten as the density of breeding females was 11.5. On 

 another unit of 131 acres, the corresponding figure was at least nine. During the same season 

 several similar coverts held only three nests per 100 acres. At the other extreme a 230-acre 



« See Chapter VUI. p. 359. 



