68 THE CONDOR Vol. XXVII 



In dorsal coloration breweri, in all plumages, presents a ground color of sandy 

 buff, with narrow streakings. In taverneri there is none of this pale sandy appearance. 

 The general ground color is grayish, with the limited brownish areas of individual 

 feathers of a darker shade than in breweri. In coarser dorsal streakings, in the fairly 

 well defined grayish area between streakings of head and back, in the suggestion of 

 a median line upon the crown, and in the fairly distinct superciliary stripe, taverneri 

 shows an approach toward the characters of Spizella pallida. 



In Juvenal plumage, taverneri and breweri present differences comparable to what 

 is seen in adults, young taverneri being darker colored generally, and more heavily 

 streaked. In later plumages there is in taverneri a tendency toward the development 

 of narrow streaks on breast and sides to a far greater extent than is ever seen in 

 breweri. This is most noticeable in certain immatures in first-winter plumage (but 

 these streaked feathers are not left-overs of the juvenal plumage), and it appears also 

 to some extent in freshly molted adults. 



In a study of the relationship of taverneri and breweri, account must be taken of 

 the geographical ranges of the two forms. Breweri finds its center of abundance in 

 the Great Basin region. It is an inhabitant of arid portions of the Upper Sonoran 

 and Transition zones, a desert bird, that, as a rule, follows the sage-brush in its dis- 

 tribution. It extends northward along the lower valleys of the interior of southern 

 British Columbia, as far as the sage-brush goes. Taverneri is an inhabitant of the 

 Alpine-Arctic zone on mountain tops far to the northward of the known range of 

 breweri. We found it only above the limit of upright timber. It occupies a higher 

 zone in the Atlin region than do the Western Tree Sparrow and the Willow Ptarmi- 

 gan ; it is associated rather with the Golden-crowned Sparrow and the Rock Ptarmigan. 

 While it would not be safe to say that taverneri occurs nowhere in the 800 miles to 

 be traversed to the southward before the nearest record station of breweri is reached, 

 still parts of that region have been visited by various collectors who have failed to find 

 either species there. 



There seem to be some notable differences in actions. Breweri is essentially a 

 retiring and unobtrusive species, though not particularly wild. Taverneri, on the other 

 hand, is extremely wary, and is frequently seen, apparently on the lookout, on the tops 

 of the stunted trees of its timberline home. On two occasions, pairs of birds, presum- 

 ably near their nests, were seen perched on the tallest bushes, jerking their tails in a 

 manner seen in no other Spizella except monticola. On the whole, considering the 

 differences in geographical distribution and the differences in zonal distribution, 

 coupled with the physical characteristics of the two forms, it seems logical to regard 

 breweri and taverneri as distinct species. 



The Timberline Sparrow is, of course, a summer visitant only, in the Atlin region. 

 It must spend the winter far to the southward, and it seems likely that the line of 

 migration lies to the eastward of the Rocky Mountains, as is the case with so many 

 non-resident birds of the region. Its winter home, however, is as yet unknown. We 

 are indebted to Dr. Joseph Grinnell for making comparisons of specimens of taverneri 

 with series of breweri in the collections of the United States National Museum, 

 including that of the Biological Survey. He failed to find a single example of 

 taverneri in those collections. It seems likely, though, that winter specimens must 

 have been collected somewhere, and it would be advisable to subject series of breweri, 

 wherever available, to close scrutiny on the chance of finding examples of taverneri 

 from southern record stations. 



