12 The Ruffed Grouse 



in the ruffed grouse is a complete absence of moulting in the spring 

 of the year. None of the thirty birds Trainer examined in the Cornell 

 University collection that might have shown this moult did so. 



Pterylosis— Feather tracts and spaces. The area of skin on the ruffed 

 grouse may be divided into ten feather tracts which are separated 

 by twelve bare areas, or spaces ( see Fig. 2 ) . These may be described 

 as follows ( Trainer, 1938 ) : ^ 



The Capital Tract includes all feathers on the head except those 

 on the under center portion. Several isolated spaces, noted later, are 

 found here. The feathers in this tract are all small, all point back- 

 ward. Longest are the erectile crest feathers. Some of the feathers 

 around the eyes are among the smallest on the body, being about 

 two millimeters long. The feathers in this tract are divided into ten 

 regions, named according to the part of the head: frontal, coronal, 

 occipital, superciliary, loral, rictal, ocular, malar, auricular, and 

 post-auricular. 



The Spinal Tract covers the upper surface of the body proper, 

 from the capital tract to the caudal tract. It is divided into three 

 regions: cervical, interscapular, and posterior. 



The Oil Gland Tract is at the posterior end of the spinal tract and 

 consists of eight little (three and four-tenths millimeters) feathers 

 arranged in a circle on the tip of the gland. 



The Caudal Tract consists of the rectrices (tail feathers) witli 

 their upper and under coverts and the feathers around the anus. 

 There are normally eighteen rectrices, although occasionally birds 

 are found with twenty ( usually males ) or sixteen ( usually females ) . 



The Ventral Tract includes the whole under side of the body from 

 the mental angle to the anal region. The foremedian portion is di- 

 vided into the interramal region from the chin to below the eyes, the 

 submalar region and the cervical region; the posterior median por- 

 tion is called the abdominal region, and the lateral portions are 

 divided into the sternal and axillar regions on each side. 



Most notable feathers in the cervical region are the five rows 

 which compose the ruff. They are situated near the middle of the 

 length of the neck. The length of the male ruff feathers increases in 

 size from sixteen millimeters to about seventv millimeters and then 



■^ The descriptions of feather tracts and spaces are derived entirely from Trainer's 

 work. 



