Steve (and Tweeters)

You did not say which Alder-type vocalization was given by your
Whidbey Island flycatcher. Was it a chip note? The chip notes of
Willow and Alder flycatchers (described respectively as "whit" and
"kep" by Kenn Kaufman in "A Field Guide to Advanced Birding") are very
different, and easily distinguished by experienced birders.

On the other hand, the Willow Flycatcher has a vocalization which is
either a call-note or abbreviated song, described by Kenn as "rrrip!".
As Kenn notes, this vocalization is "dangerously similar" to a similar
vocalization of the Alder Flycatcher-- even though the ordinary
territorial songs of these two are as different from one another as
are the songs of any 2 Empidonax species.

Was it the "rrrip" call you heard? If so, this is no evidence whatever
that the bird in question was anything other than a typical Willow
Flycatcher. I am unconvinced by all the previous reports in Washington
of "Willow Flycatchers giving Alder Flycatcher calls", all of which
appear to be poorly documented.

I am also concerned about the implication that you were able to
positively identify the bird as a Willow Flycatcher by visual field
marks alone. Separating these two species is one of the toughest
challenges in North American field identification. Your comment that
"field marks for separating these taxa are not necessarily reliable"
is an extreme understatement. Kenn Kaufman, one of the top experts on
Empidonax identification, states that "on present knowledge [1990],
Willow and Alder Flycatchers cannot be separated by sight alone, not
even in the hand". Pyle et al. in "Identification Guide to North
American Passerines" (1987) caution that the two probably cannot be
safely separated by in-hand criteria alone. It takes a combination of
a bill measurement and a wing-formula ratio to reliably separate 95%
of birds, and even then, some were misidentified, based on song type.
There are unquestionably dozens of misidentified specimens of these 2
species lying around in museum trays in North America.

You raise the possibility of hybridization between Willow and Alder
Flycatchers. To my knowledge, there is no evidence of hybridization
between these two species. (If they did hybridize, how would one ever
detect a hybrid, since the two are almost identical visually to begin
with?) In my opinion, this is a bogus argument.

Finally, I object to the use of the term "Traill's Flycatcher". Willow
and Alder Flycatcher have been well and truly demonstrated to be
distinct species. Their songs, and most of their calls, are as
different as those of any other 2 North American Empids. This is a
very different situation from the Cordilleran/Pacific-Slope split,
which is questioned by most ornithologists familiar with both forms,
and where there is good justification for continued use of the term
"Western Flycatcher". There are numerous well-documented cases of
individual birds giving vocalizations typical of both "Cordilleran"
and "Pacific-Slope" Flycatchers (i.e., vocalizations recorded on
tape). However, I don't know of a single well-documented case of one
bird giving vocalizations typical of both Willow and Alder
Flycatchers.

I have seen and heard thousands of Willow Flycatchers from all parts
of the breeding range, and hundreds of Alders. (I am admittedly less
familiar with the latter). I have never heard the same individual give
vocalizations (either songs or calls) typical of both species, and I
don't think your observation provides any more evidence that this ever
happens.

If Kenn Kaufman or someone who is more of an expert on Empid
identification than I am has any comments on this, I am sure we would
all be glad to hear them.


Wayne C. Weber
Delta, BC
contopus at telus.net




----- Original Message -----
From: Steven Mlodinow <SGMlod at AOL.COM>
To: <BIRDWG01 at LISTSERV.ARIZONA.EDU>
Sent: Thursday, July 31, 2003 1:09 PM
Subject: [BIRDWG01] Traill's Flycatcher calls


Greetings All

Some of this is old hat and was covered by a brief article in Birding
by either Mike Patton or Matt Heindel. However, for the first time,
I've heard an apparent Willow Flycatcher give an Alder Flycatcher call
(song not given). I had always wondered if Willow-types giving Alder
call notes were indeed hybrids. However...

On Whidbey Island, in w. Washington, I had a Traill's Flycatcher
giving a call typical of an Alder Flycatcher. The bird looked
absolutely typical for a western Willow Flycatcher; though I know
visual field
marks for separating these taxa are not necessarily reliable, this
bird had
nothing visually that would make me think "Alder." The bird appeared
to be an adult.

Previous Washington records of apparent Willows calling like Alders
(these birds were ID'd by visual characteristics and/or song) were in
ne. Washington, where one might think some gene introgression has
occurred; ie, a bird calling like an Alder but looking like a Willow
might have some Alder genes. Certainly, birds found during migration
in CA could be hybrids.

But, this bird in western Washington during mid-summer seems to be at
a location and date at which a hybrid (even backcross) is unlikely;
further food for thought on the reliability of call notes in
separating these species.

Cheers
Steven Mlodinow