March 01, 2018

'Oregon Junco' taxonomy

'Oregon Junco' taxonomy

Until recently, there were some issues with the taxonomy of Dark-eyed Junco (Junco hyemalis) on iNat. Those issues have now been corrected, but there are still a lot of records in the database that are attributed to the incorrect subspecies or that do not have sufficient evidence to assign a subspecies. Hopefully this post helps explain the issue.

First, brown-backed Dark-eyed Junco are often referred to as 'Oregon Junco' in field guides and other resources. Birds with this phenotype belong to one of eight well-described subspecies:

J. h. montanus
J. h. oreganus
J. h. pinosus
J. h. pontilis
J. h. shufeldti
J. h. thurberi
J. h. townsendi
J. h. mearnsi

Prior to the recent fix, the common name 'Oregon Junco' was applied only to the ssp J. h. oreganus in the iNat database, and most users were using that taxon for any brown-backed birds, regardless of their actual subspecies. In reality, many individuals cannot be assigned to subspecies from photos, especially in winter when 3 or more subspecies can occur in some areas. Some individuals with exceptional photos can be assigned to subspecies, especially records from the breeding season when the subspecies are geographically separated.

Below is a short description of the subspecies and their ranges. Note that many of the descriptions overlap, especially among the paler and more variable subspecies, and that intergrades likely are common near the boundaries of ranges. Much of this information is referenced from Cornell's 'Birds of North America'. Generally, females are not identifiable to subspecies. The subspecies are ordered from north to south in terms of their breeding range.

J. h. oreganus

Breeding range: Coastal from SE Alaska to southern British Columbia. Some individuals are year-round residents in this area and may move to lower elevations and feeders for the winter.
Wintering range: Mostly the Pacific northwest, but can be found anywhere in the west.
Male description: The darkest and most contrasting subspecies in general. Back is dark reddish brown, flanks dark reddish brown, hood typically black.

J. h. montanus

Breeding range: Central British Columbia south along the east slope of the Cascades through Oregon, extending east into NW Idaho and NW Montana.
Wintering range: primarily in lower elevation mountainous areas in Arizona, Colorado, and New Mexico but can be found virtually anywhere in the western half of the United States.
Male description: Difficult to ID and variable. Intermediate between paler southern breeders and darker northern breeders, very similar to ssp. shufeldti. Back is dark grayish brown, flanks are cinnamon from, hood varies from slate colored to nearly black. Typically less red overall than ssp. oreganus.

J. h. shufeldti

Breeding range: Pacific coast from southern British Columbia south to central Oregon.
Wintering range: Primarily along Pacific coast in breeding range and south through southern California.
Male description: Very similar to ssp. montanus and similar to ssp. oreganus but paler. Back is brownish with less red than ssp. oreganus, flanks are cinnamon brown, hood is typically black.

J. h. thurberi

Range: Nearly all mountainous regions in California, with the exception of the coast from San Francisco to Monterrey County (where it is replaced by ssp. pinosus). Also breeds in coastal southern Oregon and some areas of far western Nevada. Established in low elevation exotic Eucalyptus plantings in some areas of coastal southern California. Resident over most of its range, but descends to lower elevations in winter especially in the Sierra Nevada.
Male description: This is probably the most reported subspecies to iNat, given its year-round proximity to large population centers in California. Overall a relatively pale subspecies with minimal reddish tones. Back is brownish, sometimes with a pinkish tone, flanks are cinnamon brown, hood is blackish but variable. Sierra birds and northern populations typically are darker than birds from southern California.

J. h. pinosus

Range: San Francisco south to Monterrey County. Mostly a non-migratory resident but may move to lower elevations in winter.
Male description: A pale-headed, brightly colored subspecies. Back is bright reddish brown, flanks are bright cinnamon, hood is slate-colored or blackish. Typically brighter and more red in plumage than neighboring ssp. thurberi populations.

J. h. pontilis

Range: Resident in a small area around Laguna Hanson in northern Baja California.
Male description: Overall a dully colored bird, similar to ssp. thurberi but with pinkish flanks.

J. h. townsendi

Range: Resident in mountains of Baja California, with some individuals moving to lower elevations in winter.
Male description: Possibly the most distinct subspecies in the Oregon Group and intermediate between ssp. thurberi and 'Pink-sided Junco' (ssp. mearnsi). Overall a very dull and pink bird. Back is dull brown, flanks are pale pinkish brown, hood is the grayish and paler than most other subspecies. Sexual dimorphism is weak in this subspecies.

J. h. mearnsi (often referred to as 'Pink-sided Junco)

Breeding range: Mountainous areas from southern Alberta south through Idaho, Montana, and NE Wyoming.
Winter range: Utah east through Nebraska and south through Texas to the Chihuahuan Desert.
Male description: A distinctive subspecies, typically field identifiable from other brown-backed subspecies. Back is dull brown, infused with pink, flanks are pinkish brown, hood is grayish with dark lores. Females similar to males.

Posted on March 01, 2018 18:31 by fogartyf fogartyf | 22 comments | Leave a comment

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