Subject: A 1995 passerine fallout at Piedras Blancas
Date: Jun 10 14:10:33 1996
From: PAGODROMA at aol.com - PAGODROMA at aol.com
Dear Tweets: A few weeks ago I mentioned something about posting an item
about a passerine fallout observed here (Piedras Blancas Lighthouse, San Luis
Obispo, Co., California) during the 1995 gray whale survey season, then
phased it out and forgot. This was an amazing spectacle and something I had
only read about in historical context and never thought I'd ever be so lucky
as to actually witness such an event. So here it is, copied & pasted as
documented in my field notes. Since the original format is slightly
different, my apologies in advance if your particular email program
rearranges things somewhat.
********************
29 April 1995
weather: overcast, drizzle, light rain, and fog all day; wind ESE 10-15kt
(sunrise), then light SE-S 4-8kt; seas calm, B1-3; sea temp 12.00C; air
temp 560-560F (low/high same).
Summary: An unexpected weather situation developed suddenly overnight,
bringing in a day of rain and fog which virtually grounded the coastal
seabird migration. Pacific loons were way down (2077) with best estimate
~6600. Red-necked phalaropes were on the move again at least to early
afternoon but no where near the magnitude of yesterday. During 4.5hrs. of
intermittant effort, ~25,000 were counted with a daily total estimated at
~60,000. A single adult Franklins gull was seen flying north about 200m
offshore at 1540hrs.
There was no sunrise session due to rain & wind but mainly for the reason
described below. There was no sunset session due to rain & fog & visibility
of only about 0.2nm.
The really big news of the day was a massive migrant passerine fall-out
this morning. Inexplicably, I awoke at 0430hrs & rather grumbled that I
couldnt see the lights at San Simeon which always signal good visibility.
Not being able to go back to sleep, I got up and stumbled out the back door
and came to realize that the sky around the lighthouse was full of birds. It
was like sparks up there with many hundreds to be sure, if not thousands in
the area swarming around the rotating lighthouse beam. I scrambled to down a
cup of coffee and make my way to the top of the lighthouse in the dark to
observe this phenomeon up close. I was on the top in 15kt ESE wind driven
rain from 0500-0600hrs.
It was an utterly amazing spectacle! Warblers, vireos, and flycatchers
everywhere thumping and clanging into the light structure, others fluttering
about the light, and many others perched on the rails, deck, and anything
they could alight on. I had birds landing in my hair, on my arms, and
shoulders, and striking me in the face. Others not so lucky were stunned,
dying, or already dead on the deck. It was a most memorable experience to
see such a colorful diversity up so close in this circumstance. Wilsons,
orange-crowned, Nashville, Hermit, Townsends, black-throated gray warblers,
warbling vireos, and Empidonax flycatchers dominated and could all be seen
at once, many all lined up side by side on the rails, the light structure
spinning round and round, and perched on my folded umbrella. And if that
wasnt good enough, I could just pick them up and rearrange them! With the
first dull hints of a dark gray dawn, at 0545hrs, the swarm began to subside
and disperse into the trees, bushes, and shrubs of the oasis at the base of
the lighthouse.
A total of 23 dead birds were retrieved. These are as follows:
Deck (top of lighthouse) Ground (base of lighthouse)
orange-crowned warbler (1) warbling vireo (1)
hermit warbler (2) Townsends warbler (1)
Wilsons warbler (6) hermit warbler (2)
orange-crowned warbler (2)
Wilsons warbler (8)
Dead birds on the ground were all found on the leeward side (N & NW) and all
but one within 2 meters of the base. One Wilsons warbler was found about
20m north of the lighthouse structure in the iceplant. I was fearful that
many many more could be lost in the carpet of ice-plant that surrounds the
lighthouse, but that did not seem to be the case at all. There were quite a
few stunned birds, but alive, scattered around in the ice plant, most of
which flushed up just before I was about to step on them. I suspect that the
antennas on the top of the lighthouse are the prime suspects causing the
mortality rather than the lighthouse structure or light fixture itself. I
learned last year that before the lighthouse was modified years ago, bird
mortality was sometimes very very high, like hundreds, maybe thousands. Now,
the top has been removed and the revolving light exposed which was reportedly
done partly to reduce the bird mortality, but more likely, it was that the
top was blown off in a 1949 storm.
Apparently all of the perfect conditions required to produce this magnitude
of fall-out occurred overnight. To the south, light southerly winds and
mostly clear skies dominated the areas where migrants launched from. Flying
north, sometime after midnight, these migrants encountered the cloud deck,
rain, fog, and strong offshore wind flow. I also believe that large
fall-outs also require a dark night, ideally the night of a new moon or
close to it. This is the case at present. Even if all the other conditions
are met, the presence of a moon illuminates the coast line and sea surface,
and birds could correct their course as necessary. Even on overcast nights
when a moon is present, there is still probably sufficient ambient light to
correct a navigational error if there is one.
With the rain and poor visibility, gray whale watches were essentially
cancelled today. This allowed me considerable time to carefully and
repeatedly sort through all the passerines in the oasis and surrounding
environs. Before 0800, despite annoying rain and wind, I could focus
anywhere in the bushes and trees and see as many as six species of warblers
in one field of view, not to mention vireos, flycatchers, etc. Gradually
through the day, the flock diminished but even by sunset, a substantial
number of birds remained. The most conspicuous species were especially
Wilsons warbler and orange-crowned warbler. SEE LIST BELOW>>>
I made a quick cursorary check at Pico Creek and San Simeon State Park and
observed that there were few migrants at those sites. The major action today
was clearly at Piedras Blancas Lighthouse!
Another Allens hummingbird nest was found today in a spot where Ive
suspected a nesting bird, in the cypress north of the lighthouse maintance
building and only about 1.5m above the ground. The nest contained two eggs.
The nest outside the computer room window was looking water-logged as it
has tilted to a precipitous angle. I hope the young dont fall out before
the nest dries out or blows down.
Texaco Ponds (0815hrs): [east pond] nil; [west pond] snowy egret (1),
mallard (2), cinnamon teal (2), killdeer (4), least sandpiper (3), western
sandpiper (5).
Oasis -- (migrants & non-resident species only) -- belted kingfisher
(1-f), Pacific-slope flycatcher (10), different Empidonax flycatcher sp.
(2), western kingbird (1), ruby-crowned kinglet (1), Swainsons thrush (3),
warbling vireo (15), orange-crowned warbler (150+), Nashville warbler (10),
yellow warbler (1), black-throated gray warbler (15), hermit warbler (20),
Townsends warbler (30), common yellowthroat (3), Wilsons warbler (250+),
black-headed grosbeak (1-m), Lincolns sparrow (1), golden-crowned sparrow
(6), brown-headed cowbird (1), northern oriole (3), American goldfinch (1).
Additional visitors seen on the PB grounds but not in the oasis
included mourning dove (1), horned lark (1), tree swallow (1).
*******************
Richard Rowlett <pagodroma at aol.com>
(Bellevue, WA)
currently: Piedras Blancas Lighthouse
San Simeon, California
...but about to be Bellevue WA, ...again, ...sort of...