GRAY-HEADED JTJNCO 1099 



is practically unbroken — in a sense a "cline." Each form occupies its 

 own separate and distinct ranj^e, but each mixes freely and hybridizes 

 with its neighbors within a narrow belt, much as though all the dark- 

 eyed, northern members of the genus Junco were one species, as some 

 taxonomists consider them. The southern forms, whose chief dif- 

 ference from the northern is their yellow eye color, also form somewhat 

 of a cline, but without mixing, except within Junco phaeonotus, as 

 their "island" ranges are more widely separated and no migration 

 encourages mLxing. Presumably because all j uncos are ecological 

 equivalents and occupy the same niche in essentially similar habitat, 

 there is no sympatry of two or more species such as those in Dendroica, 

 Sitta, Paru^, and several other avian genera. The gray-headed junco 

 is especially interesting as its two races and their intergrades appear to 

 form a three-stage transitional link near the center of the "chain" 

 between the yellow-eyed juncos southward and the dark-eyed ones 

 northward, combining some of the characteristics of each group. 



The two subspecies of the gray-headed junco have had an interesting 

 and confusing taxonomic history, probably equaled by few other 

 birds. S. W. Woodhouse (1853) described the northern form as a full 

 species, Struthus caniceps, the "gray-headed snow finch." Five years 

 later T. C. Henry (1858) described the southern subspecies also as a 

 full species, Junco dorsalis, the "red-backed snowbird." 



The two subspecies have since been considered together as: a 

 single race of the Mexican junco, J. cinereus "variety" caniceps; two 

 separate races of J. cinereus (later J. phaeonotus) ; and as races of the 

 original Junco species, hyemalis. Junco caniceps has now^ for many 

 years generally been considered a separate species, but one proposal 

 made it a race of the Oregon junco, as J. oreganus caniceps, while 

 dorsalis was left as J. phaeonotus dorsalis. Jonathan Dwight (1918) 

 considered dorsalis a mere hybrid of two species, J. caniceps and J. 

 phaeonotus. The fourth edition of the A.O.U. Check-List (1931) 

 listed the two forms as Junco caniceps and Junco phaeonotus dorsalis. 

 The present status, as two races of J. caniceps, was proposed by A. H. 

 Miller (1932, 1934) and accepted by the fifth edition of the A.O.U. 

 Check-List (1957), although even Miller (1941b) recognizes dorsalis 

 as "a fully established form which gives evidence in its peculiar sub- 

 limation of characters of origin by the hybridization of J. c. caniceps 

 and J. p. palliatus,'* practically echoing Dmght's opinion. This tur- 

 bulent history has resulted mostly from the fact that such field 

 characteristics as eye color, voice, color of eggs, and manner of 

 locomotion were lost in the skins upon which classification was based. 

 Its taxonomic history emphasizes the position of Junco caniceps as 

 the connecting link between the southern and the northern juncos, 



