THE PTERYLOGRAPHY OF THE RUFFED GROUSE* 



By John E. Trainer 



The pterylography of a bird concerns the arrangement of the feathers on its body. Among 

 the different kinds of birds there is considerable variation in this characteristic, a feature 

 used extensively in studying the relationships of the various groups. Among gallinaceous birds 

 there is great similarity of arrangement and among the grouse alone it is even more uniform 

 although there are minor differences. In almost all kinds of birds the feathers grow in dis- 

 tinct tracts rather than indiscriminatelv over the surface of the body. The intervening areas 

 of bare skin, termed spaces, are covered by feathers situated in these tracts. There follows a 

 description of the various tracts and spaces (figure 82), together with a discussion of the 

 types and numbers of feathers, their variations, and a description of the "snowshoes". 



The Tracts 



The tracts in which the feathers are organized are bilaterally symmetrical. Within them 

 the feathers are generally arranged in two series of rows, one at an angle to the other. The 

 pattern is readily seen on a |)luckcd bird although in this study it was found that greater 

 accuracy resulted when the feathers were clipped. 



Capital. Included in this tract is the entire head region with the exception of the area 

 between the lower jaws. Within it there are a number of small unfeathered spaces which are 

 generally covered by feathers above and in front of them. On the top of the head one series 

 of rows radiates in all directions from the occipital region while the other makes up a set of 

 concentric circles. Both gradually unite with the spinal trad posteriorly. On the side of the 

 head one series is more or less horizontal and the other vertical. In the region of the eye 

 and ear the rows are more numerous and their feathers are highly modified. In the loral 

 region and the forward part of the malar the feathers project nearly perpendicular to the 

 skin, although their tips curve backward. 0\er the rest of the head the feathers generally 

 point backward at their base. 



The crest originates in the region between the forward pari of the eyes and is made up 

 of about fourteen enlarged feathers. Usually two are especially long. The crest of the female 

 is only slightly smaller than that of the male. 



Spinal. This covers the upper surface of the bodv fr(iin the capital tract to the caudal. 

 It is divided into the cervical, interscapular, and posterior regions. The same general plan 

 of feather arrangement is present throughout, the major series of rows sloping posteriorlv 

 away from the middle line. The secondary set of rows is not as evident, particularly in the 

 cervical and interscapular regions. In the former, the feathers intermingle with those from 

 the under side of the neck closing off the lateral cervical sjiace. The feathers increase in 

 length posteriiirh . The interscapular region is narrow because of the adjacent space which 

 is apparently needed for freedom of wing movements. The posterior region resembles an 

 inverted wide-bottom vase and encloses a large portion of the spinal space in the middle 



* The study upon wliich this aci-nutit is l)asfd wns rarried out I>y Mr. Trainer in connection with meeting the require- 

 ments for a Master of Science degree at Cornell Univeijily, 



