[Tweeters] Townsend's vs. Hermit vs. hybrid warblers by song

[Jason Zolle]

Hi tweets,

I am wondering if anyone is aware of any resources or has any useful
information they can share related to distinguishing Townsend's and Hermit
Warblers by song (1) from each other and (2) from hybrids.

To the first, I have read the relevant sections of The Warbler Guide,
looked at many sonograms, listened to numerous recordings, and while I feel
like I have a handle on identifying some songs by ear, I still am not
nearly as comfortable as I would like here, and would love some suggestions
to improve.

To the second, we birded Saturday north of Packwood in an apparent hybrid
area and the majority of TOWA/HEWA songs we heard had me throwing up my
hands in confusion.  I suspect that may have been because many were
abnormal songs of hybrids -- of the 8 birds we called in for visual
identification, 4 were phenotypically pure Townsend's and 4 were hybrids (3
of those 4 being almost pure Hermit).  I found a 1995 British Columbia
birding article online that cites a 1983 article (which I cannot find) to
the effect of "hybrids in Oregon sing like Hermit Warblers, and hybrids in
Washington sing like Townsend's Warblers."  That seems a bit simplistic and
I am hoping to get more information if possible on what to listen for (or
look for in a spectogram) so I can more confidently identify these birds by
ear without feeling the need to call each one in for a visual inspection.
I also am wondering if anyone knows whether pure Townsend's sing abnormal
songs in a hybrid zone, perhaps because they are learning from their dad's
hybrid neighbors.

I have thought that Merlin sound ID, which of course isn't perfect but
often does a good job at seeing things in spectograms that are not readily
apparent to the ear, would have been helpful in this task, but particularly
in the hybrid zone it seemed to be equally confused, often showing both
Hermit and Townsend's simultaneously or switching between the two.  (And if
it did show one bird only, that bird was almost always Hermit, which was a
bummer because not a single bird we saw visually appeared as a pure
Hermit).  This leads me to think that maybe the songs do have elements of
both that the AI is picking up on.  I just would love to know exactly what
it is seeing in the spectograms to make the call.

Thank you!
Jason
Olympia, WA
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