44 THE SPECIES— ITS TAXONOMY, RANGE, BIOLOGY, & ECONOMIC IMPORTANCE 



Other J'isual Differences 



Turning to the markings of the feathers themselves, the tail has already been described. 

 Associated with it are the markings of the rump feathers and upper tail coverts. On the 

 former the light spots (called arrowheads, ocelots, or eyes) have fine black outlines, coming 

 to a point in male birds and usually are regularly and thickly arranged. In females, these 

 spots are less distinct, not so pointed or regular in shape, fewer in number and irregularly 

 scattered, often blending with i)atches of gray and black on the brownish backgniuiid tnnc. 



Examination of the upper tail coverts will show well defined black "eyes" clearly outlined 

 by light, rich gray in cocks, while, in their mates, the "eyes" are not as black or as regularly 

 shaped — sometimes being a very dark gray or even absent altogether. Neither are the gray 

 outlines so distinct in the latter, the entire feather being dark in tone. 



Another important character is the jjosition of the wing-tips, when folded at rest, in 

 relation to the rump feathers. In the female, they usually reach the ends of the rump feathers, 

 while in the male, the rump feathers extend considerably beyond the wing tips. 



Contrary to the general color pattern, the barring of the flank feathers tends, in the female, 

 to be arranged in continuous bands of solid black on a white background. In the male, on 

 the other hand, these dark markings are more irregular in distribution and often more 

 brownish than black. 



The black and white or light buff scapular markings — like chevrons — are well defined in 

 both sexes but the blacks are richer and the lights cleaner cut in the male. 



Finally, among males, the bare spot over the upper eyelid is more pronounced and may 

 be a bright reddish-orange, especially in the breeding season. It is much duller in the female, 

 often with hardly a trace of color. 



The foregoing is intended primarily as an aid in sexing dead birds or those under close 

 observation in captivity. It is based on the study of several hundred birds of known sex in 

 captivity over a number of years. su|)plementpd by the examination of wild birds collected 

 from time to time. But, while utilization of these characters will enable one to sex grouse 

 with reasonable accuracy, it must be emphasized again that no single feature is a suitable 

 criterion. Judgment must be based on the average of all possible indices and, even then, 

 one may at times make mistakes. In fact, men with long experience on the game farm 

 many times have placed in the breeding pen, "cock" birds which have proceeded to lay eggs. 

 Gradual recognition of the differences described, however, has resulted in a virtual elimina- 

 tion of such errors in pairing the breeding stock at the New York State Research Center. 



Differences of Action 



This account would not be complete without mentioning certain distinctive activities* 

 of the two sexes. Thev are most useful with respect to wild birds and. when one is able to 

 observe them, are, in most cases, quite diagnostic. 



Primarily they are associated with the breeding season. Onlv males drum and. with rare 

 exceptions, strutting is also confined to this sex. WTien a female does strut, the performance is 

 usually short and rather incomidete. lacking pronounced feather display. On the other hand, 

 birds found on nests or with a brood are almost invarialilv females. Likewise, birds which 

 feign injury or "squeal" are hens. 



Another way in which the sex of wild grouse may sometimes be judged relates to their 



* See also Chapter V. 



