Tweeters:

A good discussion for spring, song differences of those wonderful Northwest
Dendroicas...

I'm with Wayne on the general differences between Black-throated Gray and
Townsend's, and noting habitat/behavioral differences is useful as well. I
would only differ in saying that in my experience, the Black-throated Gray
call note sounds a bit softer/flatter to my ear, and Townsend's tends to be
a bit sharper, with a more metallic quality. However distance from the bird
may blur this distinction (for example, a few times I've thought I had a
late Black-throated Gray in October, only to find, on closer approach, that
the chip note got sharper and the bird turned out to be the more likely
Townsend's). I've never been able to distinguish Hermit and Townsend's call
notes, on the other hand.

While songs of Hermit and Townsend's are truly variable, in our area it
seems Black-thr. Grays tend to stick pretty close to the two main song types
described earlier, which are quite distinctive. As Wayne noted, the fact
that they are usually delivered from a perch lower in the forest also
sometimes gives an impression of being louder. Bl-thr. Gray variant songs
are occasionally heard also, the ones I've heard have been variations or
abbreviations on the two main song types.

Chris Chappell's survey of Hermit Warbler distribution in WA some years ago
shattered some of the earlier conventional wisdom that one could identify
this species on the basis of the "chup chup" pair at the song's end alone.
I remember questioning i.d.'s on that basis only, and, when Chris went to
recheck several sites where Hermits had been assumed earlier, it turned out
that indeed it wasn't reliable. Since then, more research revealed how
heavily the two hybridize here in WA, so it makes sense that song i.d. alone
is unreliable.

Getting decent looks at any of the 3 can be tough. In the spirit of Gene's
comments, I can say that it is possible to resort to some pretty eccentric
behavior in trying to get that look (hey, we're birders, right?). Still, on
occasion one can get singing birds to drop down to investigate "pishing".
I've had best luck with Bl-throated Grays here, but sometimes Townsend's,
and on two occasions, even Hermits, came very close.

Scott Atkinson
Lake Stevens
mail to: scottratkinson at hotmail.com

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