[Tweeters] re: Warbler ID

Mike Patterson celata at pacifier.com
Thu Aug 4 07:16:56 PDT 2011


One of the pitfalls bird ID, especially at the subspecific level,
is our unrealistic expectation that every bird can and should be
place in its proper box, neatly labeled. My inclination most
days is to stay out these discussions, but since my blog was used
as a part of the discussion, I figured I'd better weigh in...

I'll start by quoting what I think is the most important point in
the article I wrote:

"...diagnosing subspecies is harder than we sometimes make it sound.
We have to figure out gender, measure the wing length, determine age.
Even at that, we leave over a third of all the birds we catch in the
subspecies undetermined pile."

Not only are there three subspecies of Orange-crowned Warbler there
are EIGHTEEN plumage types (three for each gender of each
subspecies). If we restrict diagnosis to the spring we only have to
deal with alternate (breeding) plumage. That all breaks down after June.

Joseph's bird shows a yellow gape and pointy tail feathers. That
means it's a hatch-year bird, still sporting juvenile plumage (and
please let's not get into the juvenile/juvenal nonsense). Hatch-
year Orange-crowned Warblers of all three subspecies are likely to
have grayer heads. HY females are grayer looking than males.

This bird is probably NOT _celata_. It is too bright in the
underparts and too green above, it would also be out of range for a
hatch-year _celata_ in July. If we continue to take range into
account, it is UNLIKELY to be an _orestera_ as well, but not outside
the realm of possibility (birds wander in the post-breeding season).

So, my diagnosis:
Orange-crowned Warbler subspecies undiagnosable from the photo, but
odds favor hatch-year female _lutescens_.

Here's a photo of a hatch-year _lutescens_ (probably male) from
last week on the North Oregon Coast.

http://www.flickr.com/photos/mbalame/5980431494/size/l/in/photostream/


--
Mike Patterson
Astoria, OR
Quantifying Spring
http://www.surfbirds.com/blog/northcoastdiaries/20347/




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