White-crowned Sparrow: Discussion on Geographic Variation and Correcting iNat Observations

I thought the forum would be a great place to post and perhaps become a learning experience in which we can better identify our sightings. I was given the impression to write this after a checklist on eBird reported a “rare” flock of 20 Puget Sound White-crowned Sparrows (Zonotrichia leucophrys pugetensis) in Morrow County, Oregon. Their notes were…

“Not rare. All we have seen so far have been pugetensis. Filter needs adjustment. Photos taken.”

I’ve personally birded the area for many years and I’ve yet to see any individuals suggestable of the Pacific coast variation of the species and all individuals I have seen have been Gambel’s White-crowned (Z. l. gambelii). Yet, the fact that both observers were Regional Reviewers was leaving me skeptical of my own identification skills. I’ve seen a few Puget Sound individuals when I hiked in the Cascades but not a lot. I’ve always identified inland WA and OR White-crowns as such…

– Gambel’s White-crowned (Z. l. gambelii) – Abundant except June and July – Pale lores and orange-pink bill.
– Mountain White-crowned (Z. l. oriantha) – Supposed breeder but not very common – Dark lores, sometimes dark throat with pink bill.
– Puget Sound White-crowned (Z. l. pugetensis) – Rare migrant, only 2 confirmed records east of Cascades – Pale lores and yellow bill.

So this list I’ve provided above was my methodology for identification but I started wondering with a confirmed (yes, sighting was confirmed despite no photographs) flock of 20 Puget Sound WCSP well outside their proposed range, I was beginning to wonder if I was too simplicist of my ids. I did some digging and I thought I might also post all the ranges and apparent differences of the subspecies of WCSP. Sources for information include HBW, Strokes and Sibley.

  • Zonotrichia leucophrys leucophrys (Eastern White-crowned Sparrow)
    – Breeds throughout eastern Canada, mostly Manitoba and east. Winters throughout Midwest, eastern US and northern Mexico
    – Black supraloral region and pink bill. Variable underpart coloration but mostly buff flanks and gray breast. Blackish-brown back streaking.
    – Immatures have brown supraloral region and bill color is variable from pinkish to orange. Auriculars distinctly browner.
  • Z. l. oriantha (Mountain White-crowned Sparrow)
    – Breeds throughout Rocky Mountains from British Columbia to New Mexico. Winters mostly in southwestern US and western Mexico
    – Black supraloral region and dark pink bill, some adult males have black throats. Buff flanks and gray breast usually consistent. Rusty-brown back streaking, rarely black. Rich reddish-brown wing coverts and rich brown-buff rump.
    – Immatures have “washed-out” dark supralorals and auriculars. Bill dark pink or black.
    – Nearly identical to the Eastern WCSP in plumage but differs vocally. They geographically do not overlap breeding ranges which is surprising for two very closely related subspecies. Outside of breeding range, it can be next to impossible to distinguish the two but theories of identification are being tested. It is suggestable to look for a brown-pink bill in Eastern and dark pink-blackish bill in Mountain.
  • Z. l. gambelii (Gambel’s White-crowned Sparrow)
    – Breeds throughout Alaska and western Canada to around the Hudson Bay. Winters throughout western US and northern Mexico.
    – Pale supraloral and variable bill colors from pinkish-yellowish but mostly orange. Most have solid gray upperparts, buff flanks uncommon. Dark brown back streaking. Rich reddish remiges and brown rump.
    – Immatures have fairly consistent orange bills but plumage varies extremely and probably more so than any other subspecies. Some have rich buff underparts and others solid gray. Auriculars can be distinctly dark or not. Malar stripe rare.
    – This subspecies intergrades often with the Eastern WCSP from Manitoba to the Hudson Bay, blurring the distinctness of subspecies in Midwest states. Does not seem to intergrade with Mountain WCSP.
  • Z. l. pugetensis (Puget Sound White-crowned Sparrow)
    – Breeds in coastal British Columbia to northwestern California. Small populations winter as far south as southern California.
    – Pale supraloral and yellow bill. Distinctly brown underparts. Brown back streaking. Noticeable browner wings. Short primary projection.
    – Immatures have yellow to pinkish bills. Typically very brown overall. Brown malar stripe common-uncommon.
    – Does not intergrade with any other subspecies. Sibley suggested that individuals or small flocks of this subspecies may mix with Gambel’s in the winter, east and south of its normal range, however he specifically stated that his searches for vagrant Puget Sound individuals were in Nevada and Arizona. But the Columbia River Gorge does provide the maritime gales that may cause small interruptions of the subspecies in inland WA and OR. If a possible vagrant is present, immatures may not be distinguishable.
  • Z. l. nuttalli (Nutall’s White-crowned Sparrow)
    – Resident from Mendocino County, California to Santa Barbara County.
    – Pale supraloral and variable yellow to lemon bill. Variable underparts, mostly brown but completely gray underparts do occur. Blackish-brown back streaking. Brown or reddish wings. Duskier head. Culmen distinctly curves downward. Short primary projection.
    – Immatures have yellow or dusky bills. Very brown overall, brown auriculars nearly nonexistent. Malar stripe rare.
    – Despite Sibley stating that Nuttall’s and Puget Sound WCSP are hardly distinguishable from each other, glancing at breeding adults across both subspecies’ core ranges, Nuttall’s appears to have much more variation than Puget Sound and their culmen distinctly curves downward unlike all the other subspecies. Juveniles don’t seem to have quite as much variation. They do interbreed in southwestern OR and northwestern CA.

Those are all the subspecies, ranges, brief plumage descriptions and etc. I’m going to go back through all my photos that I labeled as Gambel’s since with this newfound knowledge, perhaps I had a Puget Sound or two slip past me. And I’m sure I’m not the only one, so I’ve added this poll looking for opinions on how we can better assess White-crowned Sparrow variation on iNat. Comments and opinions appreciated as always.

  • Create a project focused on WCSP variation and properly identifying and educating members on geographic variation.
  • Identifiers interested in subspecies of WCSP review all RG observations as a secondary confirmation to the id.
  • Educate observers as they as posted.

0 voters

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