Greetings All

Wayne Weber responded to my query with the following, which I shall address
point by point

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.

--- I did indicate what vocalization, the call note (as opposed to the song).
The call was a peep, similar to that given by Hammond's Fly (and, LB Dow, if
one thinks about it).

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.

--- This is not true. For instance, Paul Lehman had 1-2 birds that looked
like Willows, sang like Willows, but called like Alders in ne. Washington last
summer.

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.

--- see recent article by Unitt in Western Birds.

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?)

--- Exactly my point. There could be hybridization between these two and such
could be easily missed. Since calls and songs are inherited in flycatchers,
birds giving the song of one and the call of the other have to at least raise
the thought of hybridization (never said it was proof)

Finally, I object to the use of the term "Traill's Flycatcher".
--- Object all you want. It is a common practice to refer to unidentified
birds from recent splits by their former "group" name. It is in no way intended
to imply that these two taxa are conspecific.


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.

--- You will note that I never heard this bird sing, and thus never suggested
that my observation did anything of the kind.


Steven Mlodinow