106 University of California Publications in Zoology [Vol. 30 



of the tail. There is a broad subterminal band of black, and the tip 

 is white, suffused with reddish. The inner, webs, and part of the outer 

 webs, are white or gray, irregularly flecked with dusky. The outer 

 rectrix (present only on the left side) has the outer web barred with 

 blackish its entire length. Below, the tail is mostly white, with small, 

 irregular dusky markings. On certain of the upper tail coverts is the 

 only part of the body plumage of the bird where distinctly chestnut 

 markings appear. 



Brooks' specimen is peculiar in that but the three outer primaries 

 are emarginate, a condition that is not supposed to exist in the Buteo 

 borealis group of hawks, where the presence of four emarginate 

 primaries has been accepted as one of the diagnostic features of the 

 species. "We examined the freshly killed bird carefully, and there is 

 no question but that the full number of primaries was present. 



The adult female in the Provincial Museum, Victoria, differs some- 

 what from the two just described. It is a darker colored bird even, 

 with the concealed white markings greatly reduced in size and number. 

 The feathers on chin, throat, and upper breast are dusky to the base. 

 The plumage generally is not so worn as in our two birds, and there is 

 hardly a trace of white showing through on the breast. 



The tail is quite different from those of the other two adults. There 

 is but a mere trace of rufous upon it. There is a terminal band of 

 black, 35 mm. to 45 mm. in width (widest on the outer feathers), and 

 above this the tail is crossed by a series of narrower bands, seven black 

 and eight light colored, the dark colored strips becoming broader 

 toward the base of the tail. The light colored areas are white on the 

 inner web, grayish on the outer. The tail differs from that of the 

 immature in the broad, black terminal band, in the lesser number of 

 narrower bands, in the more distinctly whitish color of the paler 

 areas, and in that it is more squarely truncate at the end. Individual 

 rectrices are broader and more square ended than those of the young 

 bird. The two central tail feathers of this adult are being renewed, 

 and are about one-third emerged from their sheaihs. They are of 

 exactly the same character as the others, in interesting co'nfirmation of 

 the fact that this type of plumage is retained year after year. The 

 older birds do not eventually acquire a red tail. 



This specimen has lost one primary of the left wing, giving it an 

 appearance of having but three emarginate primaries on that side, a 

 condition which is probably responsible for the misidentification of 

 the bird as Buteo swaimsoni at one time. 



