Unfortunately, I don't have any bona-fide knowledge to share, but I'd
like to point out that for diving birds, unlike waders, tidal current is
likely to be more important than tide height. In most spots that don't
have "cove," "harbor," "port," or "bay" in their name, our inland waters
tend to drop off rapidly near shore to depths of 100+ feet, so tide
heights +/- 5-10 feet are not very significant.

Presumably, diving birds find several advantages to current and
turbulence, which could push solitary bottom-dwelling fish away from
cover or encourage them to leave cover to chase food items being swept
by, and could break up schools of baitfish into more easily targeted individuals.

My recollection when doing long crossings by kayak during periods of
significant tidal current (e.g. Anacortes to the south side of Lopez Is.
and on to Friday Harbor) is that the larger alcids (Common Murre and
Rhino. Aucklet) have usually been seen feeding in areas of greatest
turbulence and current speed, such as the large tide rip E. of Bird
Rocks, while Marbled Murrelets seem to be more common in less disturbed
areas. This may be an observational error, though: I'm probably least
likely to notice smaller birds when I'm most interested in what the
rougher water is about to do to my boat!

Friday morning's flood current was predicted to be quite feeble (0.2
knots in the middle of the Sound off Edmonds), so while "about noon"
would have been getting fairly close to the predicted time of slack
water (12:43), the "peak" current earlier in the morning was not much to
right home about. This might explain why little difference was
described in the behaviour of the Ancient Murrelets at mid-tide vs. near
high tide.

I've never been in the water there, but I don't think that area is known
for impressive currents at any time. Neither is Dash Point, as far as I
can determine. OTOH, Admiralty Inlet does have quite strong currents
and is supposed to be good for A. Murrelet, so I'm not sure what to make
of this. The only reference I have (Stokes) to the feeding preference
of this bird says "crustaceans in plankton," a class of organisms I know
even less about than fish and alcids!

Mike Wagenbach
Seattle
wagen at u.washington.edu