Subject: Re: Sabine's Gull
Date: Jun 8 22:43:08 1998
From: Michael Price - mprice at mindlink.bc.ca


Hi Tweets,

Jack Bowling writes:

>A couple of weather-related theories:
>
>1) The N. Pacific High is responsible for the longshore winds along the
>California coast which Richard mentions. It is also responsible for the
>formation of a huge swath of sea stratus over the Northeast Pacific basin
(Warm
>air gets dragged up from the south flowing clockwise around the centre of
the
>high. Meeting progressively cooler water, the water vapor eventually
condenses
>out in the lower levels, gets trapped by the strong low level temperature
>inversion under the high, and voila! - a huge deck of stratus and fog in the
>east quadrants of the high pressure system). Once pushed onshore, the fog
>usually burns back offshore with the heat of the sun (or more typically,
with a
>change to an offshore wind). Maximum heating of a California land surface
in the
>summer usually occurs around 1600-1700 hours, thus that is when one can
expect
>the least onshore penetration of fog. Perhaps the Sabine's Gulls are just
taking
>advantage of the diurnal fog burnoff to make seeing where they are going
easier.
>
>2) The past week or so, the fog banks have been tenacious and widespread
along
>the west coast north from California. Usually, the Sabine's travel north
off the
>west coast of Vancouver Island (sometimes at great distances offshore).
Perhaps
>the fog banks have been so thick that the gulls decided to take an inside
>passage this week to avoid the low visibilities and give themselves a frame
of
>reference.

So it sounds like they're following the open water and making the right turn
into Juan de Fuca and then heading N into Georgia Strait; in these
conditions, this might be a very good time for Vancouver BC and Nanaimo
birders to take some walk-on ferry trips across the Strait of Georgia. A
possibly productive location is over the bank that's about 30-40 minutes W
of Horseshoe Bay on the Vancouver--Nanaimo ferry run when the tide is
changing: the resulting upwelling might bring food to the surface. It's the
only location in an otherwise pretty barren piece of water--Georgia
Strait--where one can fairly reliably find Fork-tailed Storm-Petrels
Oceanodroma furcata in migration. Come to think, the small albatross--almost
certainly a Laysan Albatross Phoebastria immutabilis--seen several
kilometers off Point Grey a few years ago by a commercial fisherman was at
this time of the year, early or mid-June. Active Pass, bird-able from
Christina Point on Mayne Island, or a sprint through on the
Vancouver--Victoria ferry, is also a good location for feeding seabirds in
large tide-rips.

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)