THE PTERYLOGRAPHY OF THE RUFFED GROUSE 747 



to the surface. They range in size from the large ones found in the lateral portions of the 

 abdominal tract to the small tufts resembling true down. 



The ruffed grouse is well known for its large aftershafts. This is a second shaft bearing 

 most of the typical feather parts and attached near the base of the main shaft. Thus the feather 

 is more or less double. In this species it is found on all of the semiplumes and the teleop- 

 tiles, except the rectrices and functional remiges. In the highly modified feathers and some 

 of the coverts, it often cannot be distinguished. In all cases it is entirely plumulaceous or 

 downy and coloring occurs only at the tip. Usually the aftershaft is one-half to three-quarters 

 the length of the main shaft. 



Numbers. The feathers of a female ruffed grouse* were counted as they were plucked. The 

 results are shown in table 101. The figures, however, represent only the number of teleoptiles 

 and semiplumes present. It is to be noted also that in some ca^es the divisions between the 

 regions of the tracts of necessity had to be arbitrary. 



TABI.K 101. NUMBER OF KMVniEHS' COUNTED ON AN INDIVIDUAL 



lUJFFED GROUSE 



♦Includes only tcleoplilcs and somiplumns. i.r^. all llip fi-jitlii-rs 



I)(i|nil;irly thoiitjhl (if ;is surh. 



Sexual variations in the number of feathers are minor. For instance, in the cervical region 

 the total number is essentially constant, although a greater number are modified to make up 

 the ruff in the male. Similarly, the occasional bird with more than eighteen tail feathers is 

 more frequently a male. In many other birds, Wetmore has found small differences between 

 the sexes in the total number of feathers and probably the same is true of this species but 

 little significance can be attached to such variations. In fact they are probably more closely 

 associated with size than with sex. 



Seasonal variations in the total number of feathers have not been studied in the ruffed 

 grouse, although Wetmore has found variation of this kind in a number of other species. j)ar- 

 ticularly among the small perching birds. Following the normal fall moult, most of the 

 feathers are immediately replaced but others do not grow until the approach of winter. Simi- 

 larly, during the spring, as the temperature increases, the number is gradually decreased by 

 shedding, a loss which is not replaced until the normal moult or later. 



Plumage Wear. Plumage wear is not readily evident until several months after the com- 

 pletion of the moult in September, the first sign appearing in the throat region. The gradual 

 fading and soiling of the plumage is not very evident until winter. It is most pronounced in 



« Taken near Ithaca, N. Y., April 27. 1937, weight 539.7 gm. 



