Hi Tweets,

Gene Hunn writes:

>It is my understanding that it is really impossible to tell Couch's from
>Tropicals in the field (and often impossible in the hand).

I believe there was an article on the separable marks in Birding a couple of
years ago.

>The calls,
>however, are quite distinct.

Thank heavens!

>Of the dozen or so Washington State records,
>several have been heard vocalizing, and all of these have been Tropicals.

Leading to the circular assumption that...

>There are no Couch's Kingbird records, to the best of my knowledge anywhere
>in the western half of the continent.

No one looks for Couch's 'cause they're told that these birds are 'all'
Tropical Kingbirds. Maybe they are, I wouldn't know, but if the alternative
to Tropical is dismissed out of hand, there's not much sense in looking, is
there? And nobody else *knows* either. Hasn't *anybody* studied the
difference on the breeding grounds to apply to these Sep-Nov birds?

So, if an observer doesn't get the calls, and doesn't get the separable
marks--whatever they are, all I can remember is that Couch's ordinarily has
a perceptibly larger bill and one of them has a darker auricular; I remember
thinking there was more difference between them than there is between some
empids that we *can* identify--where is the justification for calling them
'Tropical' Kingbird rather than 'Tyrannus sp.'?

If you can't tell, you don't know, therefore can't enter the record simply
as an assumed ID for two obvious reasons: it screws up the integrity of the
data by distorting the pattern of whatever the *actual* distribution may
turn out to be, and ignores that the opposite assumption is equally valid,
that some of these birds are missed Couch's Kingbirds--after all, they have
a post-breeding dispersal as well, don't they?.

A third reason is that accepting an ID-by-assumption undermines the
integrity of Rarity Committee standards wherein a field description not only
must at minimum establish the identification beyond reasonable doubt but has
also to eliminate completely all similar species.

Michael Price We aren't flying...we're falling with style!
Vancouver BC Canada -Buzz Lightyear, Toy Story
mprice at mindlink.net