514 



PRODUCTIVITY OF CROl SF. POPl L4TI0NS 



Sex Ratios 



Among newly-hatched grouse the proportion of males to females has been very nearly 

 equal. At the Research Center this has been true both for chicks derived from wild eggs and 

 for hand-reared stock. 



During tiie course of the Investigation the sex of birds encountered in the field has been 

 judged so far as possible. But, as many a grouse hunter knows, there is no one sure way to 

 tell males from females on sueh occasions.* Nevertheless certain criteria are available, partic- 

 ularly in the spring. At this season especially and, to a lesser degree at other times, male 

 grouse, when flushed, tend to rise rapidly from the ground while females tend to flv low for 

 some distance. The sex of drumming and nesting birds is, of course, obvious. During the 

 sunnner, too, most females are readily identified by the presence of a brood or by their broody 

 actions. 



Summer data, taking into consideration also drumming and nesting information gathered 

 during the spring, afford a reasonably accurate estimate of sex ratios at the beginning of the 

 fall period. Data for the Connecticut Hill area are shown in table 72. In compiling this 

 table, birds recorded as "sex unknown" have been omitted. 



TABLE 72. 



SUMMER SEX RATIOS OF ADULT GROUSE AS INDICATED BY 

 POPULATION ESTIMATES— CONNECTICUT HILL AREA* 

 —AUGUST 31, 1930-1942 



* Figures apply to entire area censused each year and. therefore, in many cases 

 exceed those for the portion of the area used in tracing population fluctuations. 



The average ratio of 42. .S males to 57.5 feimles indicates that the summer grouse popula- 

 tion on the Connecticut Hill area during the years covered contained more females than males. 

 At the same time ratios as low as 34 males to 66 females (approximately), and as high as 49 

 males to 51 females, indicate that the relationship is far from constant. 



On the other hand, surveys conducted on the smaller Adirondack area failed to indicate a 

 consistent predominance of females in the summer population (table 73). 



Because spring surveys on the Adirondack area were primarily designed to provide breed- 

 ing population estimates, detailed drumming and nesting information was not recorded. 

 Therefore, aside from females with broods, it was necessary to judge largely by flight char- 

 acteristics when the birds were flushed. The number of individuals was low and the results as 

 noted are inconsistent. X^IIiellicr these data are of sufncient weight to invalidate the idea 



» See Chapter U, p. 39. 



