TAXONOMY 39 



How TO Recognize Sex* 



How to tell male from female has always been a matter of interest among sportsmen. From 

 the stag and wild boar of the mediaeval sons of Diana to the grouse and pheasant of contem- 

 porary scattergun enthusiasts, there has been a tendency to prize male specimens more highly. 

 But, while the males of many game species have distinctive adornments or plumage, in others 

 Nature has been much less lavish. Among the latter is the ruffed grouse. 



Positive determination of sex must, of course, depend on examination of the gonads^. 

 In birds, this is often difficult, especially for the untrained observer, since the organs are 

 internal and very small, except during the breeding season. Therefore, a knowledge of any 

 features of coloration, external anatomy or actions, which tend to distinguish the sexes, is 

 desirable. 



The Investigation has had unusual opportunities for observing such differences in grouse, 

 particularly with respect to artificially propagated stock at the Research Center. Constant 

 association with birds at this unit, as well as in the field, has led to the recognition of certain 

 characteristics as indicative of male or female '. Activities such as drumming and nesting are, 

 of course, quite definite criteria of sex. but features of feather marking and bodily propor- 

 tions are much less distinct. The latter will be considered first. 



Before discussing these differences in appearance, it should be pointed out that no one 

 characteri.stic, or even a combination, is infallible. In general, they represent extremes of 

 variations which exhibit all degrees of intergradation. Thus it would be a very unusual bird 

 which would |)()ssess all of them as described for its sex, yet most specimens will have a 

 majority. 



One must also realize that the characters are largely relative and, unless one has a suitable 

 basis for comparison (either a series of other specimens or wide personal experience), 

 judgment is diflficult. Furthermore, the features associated with bodily proportions apply 

 primarily to living grouse, although many of them can, with care, be used for freshly killed 

 birds. 



The accompanying illustrations will be helpful in visualizing most of the differences dis- 

 cussed. In studying both paintings'' and marginal sketches, one should keep in mind that 

 the extremes have been pictured in order to emphasize the various characteristics. 



The First Things to Look For 



Perhaps the most diagnostic external feature is the tail. Birds having the broad, dark, 

 subterminal band uniform over all tail feathers are almost invariably cocks, only one excep- 

 tion having come to the authors' attention. But, if this band is broken on the two middle 

 feathers, the bird may be either male or female. In such cases, the length of the tail should 

 be determined. In males, this appendage tends to be over six inches long: in females, it is 

 shorter. Exceptions are not unusual, however, and a more applicable rule would be to con- 

 sider only those of six and a quarter inches or over as male, and five and three-quarters inches 

 or less as female. When the tail band is broken, the mottled design in this area is apt to 

 be coarser among the cocks. Moreover, a closeup view of the tail will show a tendency in 



* This account has hrm written hy Fred. Everett, who. while studying tlie birds at the Resrarrli Center and painting the colored 



illustrations for the book, discovered a number of previously unrecognized differences. 

 A See discussion of Anatomy, p. 59. _ _ 



t The material upon which this discussion is based was derived from the stock inhabiting New York, which involves only the 



subspecies itmhetlus and logato. It seems probable, however, that the characters noted will be found to hold, in general, for 



the other races. 

 t See color plate facing p. 40. 



