294 The Ruffed Grouse 



raised a single brood year after year, aiid another of nineteen acres 

 raised two broods in some years. No smaller isolated coverts I have 

 known have maintained a grouse brood tliroughout the summer. 



The average brood travels over a much more extensive area than 

 this. An average territory diameter of one-quarter mile is about nor- 

 mal, while extremes of travel range from possibly a very few acres 

 (a brood flushed every time from June through August in a single 

 briar patch ) , to several hundreds of acres over a diameter of at least 

 one and five-tenths miles. 



Densities of Adult Populations. Densities of game bird populations 

 are usually taken during the spring breeding season and at the peak 

 population period in late summer or early autumn just as the young 

 birds have matured. For the grouse these times are April and Sep- 

 tember. Because the grouse uses only a part of the total range in 

 partly farmed areas like Connecticut Hill, all figures are based on 

 the ratio of area of coverts, exclusive of open land, to numbers of 

 grouse. 



For this area as a whole, the greatest breeding season density 

 was about a grouse per nine acres. The lowest was thirty-six acres 

 per grouse, although lower densities had occurred before 1930. 

 Most years, the density was nearer the maximum. 



There is less variability in the population density during the 

 peak period than in the breeding season. The greatest density was 

 five and two-tenths acres per grouse and the least nineteen acres 

 per grouse. Whatever the breeding density of grouse may be, within 

 the limit of a grouse per eighteen acres, the summer's productivity 

 will normally bring tie population up to a fairly high and fairly 

 constant level in September. Stating this another way, a satisfactory 

 fall population normally results from any breeding population that 

 has not fallen below a density of a bird per eighteen acres. The 

 effect of high breeding populations in reducing the recovery rate 

 tends to prevent irruptive peaks, thus somewhat stabilizing the 

 population. 



The October hunting season densities are from about five to 

 twenty-five per cent below the early September figures, the average 

 drop being about twelve to fifteen per cent. 



When we consider individual coverts (units of cover that are 

 more or less isolated from other cover by open fields, and ranging 



