Sunday, December 9, 2012

Dark-eyed Juncos - a photo study

Although Dakota Ridge Trail in Boulder County is getting a lot of attention right now for the Northern Cardinal that's been hanging out for the past month, it's also had a tremendous abundance and variety of Dark-eyed Juncos on each of our recent visits.

Dark-eyed Juncos are a unique species, as they are actually made up of a large number of subspecies which can be grouped into 6 (or 5, depending on who you ask) groups that can be readily identified in the field. Each group has distinctive field marks, and there are also noticeable differences in size and song. Each group occupies a different range, with lots of intergradation where their ranges overlap. I've found Sibley's Field Guide to Birds to provide the best overview on each group, with excellent identification tips and helpful range maps.

SLATE-COLORED - Junco hyemalis hyemalis group

Slate-coloreds may be the most widespread group, breeding from coast to coast above the U.S. - Canada border, and wintering from coast to coast in the lower 48.

Dark-eyed Junco (slate-colored). Female on the left, male on the right.
Dakota Ridge Trail, Boulder County. December 8, 2012.
eBird range map for slate-colored Dark-eyed Junco.

OREGON - Junco hyemalis oreganus group

Oregon's may be the second most widespread, living year-round on most of the Pacific Coast, wintering in the western half of the United States and some of Mexico, and regularly straying through the rest of the lower 48, except for the south east.

Dark-eyed Junco (Oregon).
Dakota Ridge Trail, Boulder County. December 8, 2012.
eBird range map for Oregon Dark-eyed Junco.


GRAY-HEADED - Junco hyemalis caniceps

Gray-headeds are somewhat of a south-west specialty. They breed in Nevada, Utah, Colorado, and New Mexico, winter in Arizona, New Mexico, and some of Texas and Mexico, and regularly stray to surrounding states. For the past few weeks, they have been by far the most abundant subspecies at Dakota Ridge Trail.

Dark-eyed Junco (gray-headed).
Dakota Ridge Trail, Boulder County. December 8, 2012.
eBird range map for gray-headed Dark-eyed Junco.


PINK-SIDED - Junco hyemalis mearnsi

Pink-sideds occur mainly in the intermountain west, breeding in Idaho, Montana, and Wyoming, wintering in Colorado, New Mexico, Arizona, and parts of Texas and Mexico, and regularly straying into nearby states. They were also quite abundant at Dakota Ridge Trail.

Dark-eyed Junco (pink-sided).
Dakota Ridge Trail, Boulder County. December 8, 2012.
eBird range map for pink-sided Dark-eyed Junco.


WHITE-WINGED - Junco hyemalis aikeni

White-wingeds are perhaps the least common, and have a very limited range. They live year-round in an area surrounding the intersection of Montana, Wyoming, and South Dakota, winter south into Colorado, and occasionally stray a little further south or north. We were lucky enough to spot one on two trips out of the last three.

Dark-eyed Junco (white-winged).
Dakota Ridge Trail, Boulder County. December 8, 2012.
eBird range map for white-winged Dark-eyed Junco.

You have to be careful distinguishing slate-colored from white-winged in areas where they overlap, as about 1 in 200 slate-coloreds have white wing bars that are about as strong as the white-winged. White-wingeds should be distinguished on the combination of all characteristics (and not just one alone), including having darker lores, and a paler shade of gray, particularly on the throat.


RED-BACKED - Junco hyemalis dorsalis

Red-backeds live year round in central Arizona and New Mexico, and stray or winter just a little further south. None were found at Dakota Ridge trail. They are very similar to gray-headed, except that they have a bicolored bill, with the upper mandible a darker color than the lower.

eBird range map for red-backed Dark-eyed Junco.

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