1102 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 2 



commonly, Pseudotsuga. Birds also breed in pure groves of aspens and in conif- 

 erous forests with some oaks intermixed. Compared with the habitats of 

 J. c. caniceps, those in which I have found dorsalis are, if anything, less arid, 

 more luxuriant forests, although occasionally birds will breed in the dry lower 

 portions of the yellow pine belt. Ground cover is rarely as poor in grass, low 

 bushes, and humus as in many parts of the range of J. c. cankeps in Utah and 

 Nevada. However, the presence of good stands of yellow pine in the Transition 

 zone provide [sic] junco habitat at lower zonal levels than in Utah and Colorado. 



E. A. Alearns (1890a) found in east central Arizona that "Typical 

 dorsalis breeds very plentifully through the northern MogoUon and 

 San Francisco Mountains, but does not appear until one has ascended 

 a considerable distance into the pine belt. It is the most character- 

 istic bird of this higher region * * *." 



The observations of these and several other writers indicate that the 

 breeding range of dorsalis extends lower than that of caniceps. The 

 ponderosa pine forest of the two more southern states, New Mexico 

 and Arizona, is less arid and more luxuriant than most of that of 

 Colorado, Utah, and Nevada, suggesting that the lower edges of the 

 more northern pine forest may be too arid for suitable junco habitat. 

 At the other altitudinal extreme, dorsalis seems generally not to breed 

 as high as caniceps. W. W. Cooke {in Bailey, 1928) states its breeding 

 range as "Transition and Canadian Zones of high mountains in Arizona 

 and north central to southern New Mexico," but probably not "much 

 if any above 9000 feet," while the breeding range of caniceps is given as 

 "Hudsonian and Canadian Zones," up even to 12,400 feet at one 

 locality. 



Spring. — As spring approaches and the northern gray-headed junco 

 (caniceps) starts northward and upward toward its summer home, the 

 proportion of this species in the mixed flocks of juncos in their winter 

 haunts thins noticeably. At Paonia, in central western Colorado, 

 in the Upper Sonoran pinon-juniper and scrub oak country. Homer 

 Griffin wrote me: "Gray-headed, pink-sided [J. oreganus mearnsi], 

 and Oregon [J. o. montanus] juncos were present all winter; gray- 

 headed juncos made up the majority of the population during March 

 and pink-sided juncos during April." On the plains in the vicinity of 

 Denver, Colo., the gray-headed has almost entirely left for the moun- 

 tains by May 1, while the more northern Oregon and slate-colored 

 (J. hyemalis) juncos are still present in numbers. 



The gray-headed junco becomes plentiful in the vicinity of its 

 breeding territories long before conditions are suitable for nesting. 

 F. C. Lincoln (1920) took a specimen in Colorado at a garbage pit at 

 10,400 feet. Mar. 31, 1915, when "snow was from 3 to 15 feet deep and 

 this bird's presence is more or less * * * a mystery to me." Up to 

 timberUne in the Colorado mountains the males sing freely in the tops 

 of the tallest pines or spruces while the ground is still covered by two 



