Biography 51 



by the male birds. Observations show these maximum averages in 

 various coverts to run from about ten to over a hundred acres. Cer- 

 tainly no male bird ever tried to defend a hundred-acre territory, 

 but what the limits of a bird's ambition would be when given full 

 freedom to take as much territory as he wished is a matter of con- 

 jecture. Also, some males have gotten along with considerably less 

 than ten acres. It is my judgment that when the spacing of male 

 territories is such that less than twenty acres are available to each 

 bird, the pressure between them becomes continuously active. 



The second concept of territory is that area that an individual, 

 or a brood, or a group, requires and uses in its year-round or seasonal 

 activity. There is less connotation of conflict or of exclusive rights 

 in this type of territory, although at times conflict does occur. The 

 fall shuffle is the main occasion for this type of territorial activity. 

 Evidence is that an average of four acres per bird is the minimum 

 requirement. It will be noted that this figure corresponds to maxi- 

 mum cariying capacity ( saturation point ) and roughly corresponds 

 to the minimum average figure for male spring territories ( ten acres 

 —or five per giouse if sexes were equally divided). This type of 

 territory establishment does not mean a separation of area for each 

 bird or group; rather it is the area utilized by them as a unit and 

 only during the fall shuffle may it result in the exclusion of other 

 birds from overlapping. An average of eight acres per bird for a 

 group of six would indicate a forty-eight-acre territory for that 

 season. 



Territory on the part of the brood is simply the area they cover 

 during the summer. No interbrood conflict is involved and terri- 

 tories often overlap— even occasionally are practically concurrent. 

 The area required to raise a brood also varies— generally twenty to 

 forty acres is utilized. Cases have been observed of broods living the 

 entire summer in an area of about ten acres while other cases have 

 involved in excess of a hundred acres. The latter cases are usually 

 the result of abnormal movements resulting from disturbance. 



Daily and Seasonal Range. The spring range of the male corre- 

 sponds to his territory, while the sum of the seasonal ranges of all 

 grouse add up to their yearly territory. However, seasonal ranges 

 vary considerably. The spring range of the female, during egg lay- 

 ing and incubation is very restricted, often as little as three or four 



