Hi Tweets,

Jane Westervelt writes:

>In my experience, PS flycatchers commonly drop the first note of
>their call, which, from my understanding of the differences in calls,
>would make them sound like a Cordilleran. I've sat and watched
>the same bird make both calls like you describe on numerous
>occasions.
>With that in mind, I'd like to think there was more reasoning than
>song behind this split.

Jane, I wish this made things simpler but it doesn't. Pacific-slope
Flycatcher Empidonax difficilis is a common breeding bird in this type of
habitat in Vancouver BC and while I heard a number of territorial and
near-nest vocals, this is the first time I've heard the Cordilleran
Flycatcher E. occidentalis call. Dick Cannings once played a tape with both
their calls, and the Stanley Park bird was giving an exemplary occidentalis
call, not simply dropping a note, unless the occidentalis call is simply the
result of dropping a note.

Which raises the question: how do you then separate difficilis from
occidentalis without a sonogram dingus? Wotta headache this split has turned
out to be.

Michael Price A brave world, Sir,
Vancouver BC Canada full of religion, knavery, and change;
mprice at mindlink.net we shall shortly see better days.
Aphra Behn (1640-1689)