The foothills of the Colorado Front Range provide wintering habitat for several races of the Junco complex. One can easily observe Gray-headed Junco (Junco caniceps caniceps) as well as five recognizable forms of Dark-eyed Junco (J. hyemalis). Listed in general order of occurrence, these forms include Pink-sided Junco (J. h. mearnsi), dark-hooded forms of Oregon Junco (J. h. oreganus), Slate-colored Junco (J. h. hyemalis), and White-winged Junco (J. h. aikeni).
Among one mixed Junco flock coming to feeders along Bluebell Canyon in Boulder County, Colorado, were two individuals which, by plumage characteristics, appeared to be vividly marked intergrades between caniceps and mearnsi. The flank color (typically gray in caniceps and warm buff in mearnsi) of both intergrades was a warm rusty-buff.