Date: 12/30/24 11:00 am From: Alex Rinkert <arinkert...> Subject: Re: [MBBIRDS] White Wagtail, Wilder Ranch SP
There are a few additional field marks worth mentioning that can be
important for subspecific identification of a White Wagtail with this
appearance. At least one of the tertials is replaced, so this is probably a
first winter bird. In my flight photos, the primary coverts show a good
amount of white, as do the median coverts and primaries, with the white
broadening toward the base of the latter feathers. In one photo of the
spread tail, the right outermost tail feather appears solid white. I'm
certainly no wagtail authority, but with the age of this bird in mind, it
seems that these field marks and others point to the Black-backed (lugens)
subspecies. I hope that Per Alström will weigh in again as more photos are
obtained during its stay at Wilder Beach.
On a side note, both the lugens and ocularis subspecies have occurred in
SCZ, and a substantial number of records for both of these subspecies have
accumulated in California, so one is not necessarily much more likely to
occur here than the other.
Alex
On Mon, Dec 30, 2024 at 8:37 AM Erik Enbody <erik.enbody...> wrote:
> Hey Glen et al,
>
> I’ve also been curious about the subspecies on this excellent find by Emma
> Arul on the CBC and have been looking through yours and others photos of
> the bird. The identification of first winter or adult winter female lugens
> (black backed) and ocularis is not always possible in the field and this
> individual seems to be along this gradient somewhere. However, if the bird
> is a first winter, which I think it likely is, the white greater coverts
> with dark centers (visible in the highest resolution photos) are more
> consistent with lugens, whereas ocularis tends to retain their juvenile
> coverts into the winter (which would appear as two white wing bars). The
> thicker and messier eye stripe behind the eye is also closer to lugens. In
> some angles of photos I’ve seen, it looks like a few dark centers on
> feathers on the back, but this isn’t always apparent and could be a
> photographic artifact.
>
> I asked Per Alström, the author of the wagtail book, who agrees it is
> likely a lugens. However, he wasn’t sure it was identifiable from the
> photos available yet. If anyone can get a clear flight shot that shows the
> spread wing clearly, this would help get a little closer.
>
> Best,
>
> Erik
>
> --
> Erik Enbody
> Postdoctoral Scholar
> UC Santa Cruz / California Conservation Genomics Project
>
> January 2025:
> Susan E. Lynch Assistant Professor
> Department of Computational Biology
> Cornell University
> erikenbody.github.io
>
> On Dec 30, 2024, at 1:09 AM, 'Glen Tepke' via mbbirds <
> <mbbirds...> wrote:
>
> PS: I understand that this bird has been identified as ocularis, which is
> the most likely subspecies here, but I am curious about how the subspecies
> ID was determined. To my eye, the extensive white wing panel, thick black
> post-ocular line connecting to a prominent triangular post-ocular spot, and
> medium gray (not black) crown fit Sibley's illustration of 1st winter
> female lugens (Black-backed) just as well as any of the other plumages
> illustrated in Sibley or Nat Geo. Several photos are in this checklist:
>
> https://ebird.org/checklist/S207155378 >
> Glen Tepke
>
> On 12/29/2024 3:12 PM, 'Glen Tepke' via mbbirds wrote:
>
> The White Wagtail on Wilder Beach continues today. Jake Gifford spotted
> it around 2:00 and we had it in view for about 10 minutes before it
> disappeared. It was fairly close to the overlook, roughly between a fifth
> and a quarter of the way down the beach, foraging around the driftwood logs
> and wrack.
>
> Glen Tepke
> Santa Cruz
>
>
>
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