In a message dated 97-12-03, Michael Price writes (privately) but I'll share
my reply with all 'tweeters' (and the ID-Frontiers group) as it may be of
collective interest --

<< ....In the remarks regarding separation from the
very similar Short-tailed Shearwater P. tenuirostris the observer asserts
that axillary feather-color is a *reliable* guide to identity, SOSH having
paler axillars than STSH.

To quote from the report (which, incidentally, eliminates the other
shearwaters from consideration quite nicely): "The underwing pattern can be
variable but I have always found STSH to be blacker in the axillars whereas
SOSH are white..." >>

Hi Michael --

I would have to say that wing linings (white vs dusky) standing alone in
establishing Sooty vs Short-tailed Shearwater identification is insufficient.
There is quite a large percentage of Short-taileds that show as much (in some
cases, more) white or paleness on the underwing including the 'axillars' as
Sooties. I collected and examined thousands of Short-taileds killed
incidentally in the Japanese high seas salmon driftnet fisheries back and all
through the early to mid 1980's in the Aleutians out around Attu which bear
this out, many of which now reside, mostly as skeletal material however, at
the Burke Museum, University of Washington. I'm not sure how many showing the
wing variation may have been saved as study skins or wings, but Carol Spa,
et.al. did a pretty good job at building a nice comparative collection from
those. Back then, I was absolutely impressed by the variability of Short-
tailed's and tended to select and save back the extreme cases along with a
complete range of variation. The rest I tossed overboard just because of the
sheer depressing volume. I haven't actually handled very many Sooty
Shearwaters by comparison, Sooty out there (western Aleutians) and in the
Bering being something of a rarity.

It seems to hold that with respects to Sooty Shearwater, I'd have to agree,
the wing linings and 'axillars' are always white or at least perceived to
appear pale or silvery, with on occasion a few in the borderline paler realm,
maybe blotched a bit, thus could possibly be interpreted as perhaps fitting in
the marginal "dusky" category and identified as Short-tailed by an observer
with little and/or infrequent experience with gazillions of Sooty and
variations of Short-tailed Shearwaters. Generally, I've come to what I
currently feel is a safe conclusion that Sooty Shearwaters will always show
white or silvery appearing wing linings, including the axillars and never
appear dark, or dark enough to be confused. Short-tailed Shearwaters could go
either way, including the axillars and those ones can be the problem.

However, in the report submitted to you, there seems to be nothing, or it's
not mentioned, regarding other useful aspects of Sooty vs Short-tailed
Shearwater identification, specifically, the head and bill. Lots of
comparative experience is necessary to put this into perspective. Sooty
Shearwater by a few percentage points is a larger bird, and this is further
accentuated by the rather longish look to the head and bill. The bill is
(comparatively) long and thicker, the neck is usually stretched a tad, and the
head has an ever so slight rectangular look to it. The Short-tailed often
poses a rather no-neck look, kind of scrunched up, the head is round all-in-
all giving it a rather fulmarish thick and steep foreheaded look, yet still by
comparison to Sooty, smallish and rounded dove-like, and the bill is short and
thin. Most Short-tailed Shearwaters show a variably small area of paler brown
to tan on the chin at the base of the bill and sometimes extending to the
throat, something which Sooties almost never do unless feathers are worn a bit
or stained with something. Generally, even in June, Sooty Shearwaters appear
more contrasting and harsh against their ocean water environment, being darker
brown to blackish, while Short-tailed's seem to appear an almost pastel shade
of brown (i.e smoother or with less contrast). Short-tailed's are a bit
smaller and more compact often with more dashing or rapid fluttery flight
while Sooties tend to appear more gangly and languid. Of course, these
subtlties are all highly variable and open to interpretation depending on
lighting, wind, and sea conditions, distance and angle, and the observers
experience. Mid-day high summer sunlight can be particularly tricky where at
times all these dark shearwater species can give off a dark morph fulmar jizz.

I guess if I were the one evaluating the sighting, and since you further
write: "...The observer has done many pelagic trips, has high ID skill-levels,
seems fairly comfortable in differentiating the two species, and seems
positive of this ID, citing also the bright white underwing flash...",
especially the part saying *bright white underwing flash* as this does
contrast more with a generally darker bird, I'd tend to buy the Sooty
Shearwater identification as submitted. An early-mid June record off
Vancouver's Iona Jetty would seem to make Sooty more plausible, but then,
birds being birds, we all know that anything is possible.

Mike Force is due back in town (Vancouver) on 12/13, coming off the Canadian
R/V "Riker" working up in the Gulf of Alaska. [What's that doing up there? I
thought 'we' were at war '-)] You might want to hit him for a second opinion
and on the 'axillars' question if that is the specific cinching point of
contention. Mike tends to gravitate towards and focus on some really finite
tiny details, much to his commendation, and not so infrequently, ones that
have escaped me and perhaps we have not discussed amidst our cruises together.
If you do connect with Mike, best you get on it early as he is turning around
pretty fast to be off to the Antarctic and Chile until at least next Spring.
BTW, who submitted the sighting record? Mike Force? '-) You don't have to
answer that :-))

Richard Rowlett (Pagodroma at aol.com)
47.56N, 122.13W
(Seattle/Bellevue, WA USA)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
God was my co-pilot,
but when we crashed in the mountains,
I had to eat him :-))
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