94 DWIGHT 



feathers of the forehead which fall out a little later. We see 

 new feathers centrally on the crown in advance of those on the 

 occiput, and the loral and circumocular regions are often 

 bare when the crown and auriculars are largely renewed, and 

 especially is this noticeable in very young birds. The last 

 traces of moult are, as a rule, to be found in the postauricular 

 and cervical regions. 



The head tract is of paramount importance because if any 

 partial prenuptial moult takes place, the new feathers will be 

 found here and on the chin and often nowhere else. In some 

 species the renewal is limited chiefly to the loral feathers and 

 those adjacent, or it may involve the crown and anterior parts of 

 the throat. Adult males may or may not renew this tract at the 

 prenuptial moult according to species ; young males in many 

 species renew it their first spring only (possibly their second 

 in some cases) ; and females may moult the same as the males, 

 but more frequently either omit this moult altogether or as- 

 sume a very limited number of new feathers. Young males of 

 the same species may show the greatest individual variation, 

 especially in highly colored species, some of them assuming 

 plumage indistinguishable from adults, others only a few 

 scattered feathers at the anterior parts of the head and throat. 

 Each species, however, has a tolerably definite area of renewal 

 peculiar to itself and although the feathers of the head tract are 

 very numerous they are, most of them, so extremely small that 

 their moult may be very easily overlooked. 



4 . Dorsal or Spinal Tract [Ptcryla spinalis) . The slight variations 

 in the distribution of this tract among our families of Passeres 

 need not be here specified. It extends in most of them from 

 the occiput to the oil gland at the base of the tail, widening 

 posterior to the scapulse into a triangular " saddle," some- 

 times dividing into two bands and enclosing an elliptical space 

 instead, and sometimes forking and ceasing before reaching the 

 oil gland. 



The first place where new feathers show is at a spot in the 

 anterior interscapular region. There seems also to be another 

 spot behind the saddle where as the tract is narrow the moult 



