"Red-backed" Dark-eyed Junco (Junco hyemalis dorsalis), Santa Rita Mountains, Santa Cruz County

"Red-backed" Dark-eyed Junco is very rare in the SE Arizona breeding range of Yellow-eyed Junco (see below). This bird was discovered high in the Santa Rita Mountains on 8 February 2008 by Rich Hoyer and subsequently photographed by Laurens Halsey along the Agua Caliente Trail at an altitude of 7300 ft (2225 m) on 13 February 2008.  The occurrence of this nonmigratory taxa high in the Santa Ritas raises the tantalizing possibility: Could they be breeding there?  Something to be watching out for!

Junco taxonomy is complex.  At least seven different taxa occur in Arizona with variable frequency.  There are three taxa that have gray heads, gray sides and rufous backs.  All three breed in the state.  “Gray-headed” Dark-eyed Junco (Junco heymalis caniceps) breeds in extreme NE Arizona, is migratory and winters irregularly in much of the rest of the state.  “Red-backed” Dark-eyed Junco (J. h. dorsalis) breeds in the North central mountains and is largely sedentary, showing only altitudinal migration.  The Yellow-eyed Junco (J. phaeonotus), currently considered a separate species, breeds in the mountains of Southeast Arizona and is also largely sedentary, with only limited altitudinal migration.  

Of these taxa, the “Gray-headed” Dark-eyed Junco is the most distinctive.  It has dark gray underparts and wings, a flesh colored bill and of course the dark iris.  It sings a typical Dark-eyed Junco trill.  The other two taxa, “Red-backed” Dark-eyed Junco and Yellow-eyed Junco, are more similar to each other in plumage, song and breeding/migratory behavior, really differing only in eye color and the amount of rufous in the wing coverts. Both differ from “Gray-headed” Dark-eyed Junco in having a bicolored bill (dark gray upper mandible, silvery lower mandible in Red-backed, yellowish lower mandible in Yellow-eyed), light gray underparts and usually some rufous in the wing coverts (more extensive in Yellow-eyed, sometimes absent or faint in Red-backed).  Both of these forms have similar songs that differ from the trill of other juncos.  In many ways, Red-backed Junco is just the dark-eyed form of Yellow-eyed Junco.  I said it was complex!

Fig 1.  With the two-toned gray bill and dark eye this could only be a "Red-backed" Dark-eyed Junco (J. h. dorsalis).  This identification is also supported by the light gray throat and breast that contrast with the darker head.  A "Gray-headed" Dark-eyed Junco (J. h. caniceps) would have a flesh colored bill and darker underparts that do not contrast with the head.  The relative lack of rufous in the wing coverts also eliminates an aberrant Yellow-eyed Junco.

 13 February 2008 photo by Laurens Halsey