[Tweeters] Possible Black Swift (long)

[Michael Price]

Hi tweets

Sound like a Black Swift to me: appearance and locality sound just right.
Their current scarcity is relatively recent, and they might still be found
when conditions are right.

It's often said that Black Swifts appear only in very small numbers at sea
level almost only when it's overcast, in advance of an incoming Pacific
Low. That's usually how I saw them. Except when I started seeing them
regularly in larger numbers under very different conditions. But that's
likely a historical construct.

True to script, I saw my first-ever Black Swifts one overcast afternoon in
the early 80s when Mike Force and I were watching a skirmish line of
several BLSW just over the water of the outer pond at Iona Island in
Richmond BC. The birds were about 5 meters above the water, flying parallel
to each other upwind into a gentle southeasterly breeze (in Vancouver BC, a
southeasterly is our incoming rain-envelope wind). Whenever they reached
the eastern edge of the pond, they wore downwind back to the western edge
and reorganised their line. Rinse and repeat several times.

Then there were the exceptions. These required a different physical
topology, but they were consistent, and most close to sea level.

1. On any warm late afternoon or evening between June and August above the
heritage park behind the Museum of Anthropology out at UBC in the 80s and
90s, there'd be large numbers of both swift species, swallows and
nighthawks. This location is near the western end of Point Grey, nearly 200
ft/60m above Burrard Inlet, just south and east of the west- and
northwest-facing cliffs. They still may show up there.

2.  In the 80s and 90s, I lived in the NW corner of Kitsilano, a
residential district on the west side of Vancouver BC. Most late summer
afternoons and early evenings, I could open my south-facing window and
watch Black Swifts low and close, often so close I could hear their
vocalisations and even could hear their bills snapping shut as they hawked
insects. To the south of my house, there was a high southwest--northeast
ridge.

3. On hot, humid later-summer afternoons in the 80s and 90s, when there
were multiple ant/termite hatches on Vancouver's West side, I would
sometimes see the sky jammed full of hawking swallows, Black and Vaux's
Swifts and the smaller gull species---Bonaparte's, Ring-billed, California,
even maybe a couple of juv Franklin's---heck, even some Glaucous-wingeds
clomping about with all the grace and elegance of WWE wrestlers auditioning
for Swan Lake), up to the upper limit of the 10x40 bins in my backpack.
Well, used to. Swifts and swallows and nighthawks are all pretty much gone
now: I've yet to see one this summer in my neighborhood where twenty years
ago they were almost absurdly abundant from mid-April on. To the south,
there was a long east--west ridge.

4. In the first decade of the 2000s, I would take my mid-afternoon lunch to
the east-facing back porch of the business where I worked in East
Vancouver. It was a pretty standard small/specialty-retail district on a
busy street. Hardly typical Black Swift territory. But any warm sunny day
from mid-June to early August, I could sit and watch up to 5-10 Black
Swifts amid the Vaux's and the swallows hawking their prey above the
alleyway behind the store at distances ranging from 10-150 meters. They
were there every afternoon from mid-June to their southbound departure in
August as long as a warm west wind blew. Never got tired of watching them,
especially when they would deliberately go into their hammerhead stalls,
something the Vaux's never did. This location was at the western base of a
long north--south ridge

What did these sites have in common? Ridges and warm westerly to
northwesterly breezes---winds such as this region typically gets when the
semi-permanent Pacific High sets up shop offshore from June to September,
creating up-drafting ridge waves lifting airborne insects for the local
aerial insectivores to chow down on. These ridge-wave updrafts are swift-
and swallow magnets.

So, I'd guess that if you're where the topology's flat, you're gonna have
to wait for an incoming Low to come trundling in off the Pacific and trust
to luck, but if you can find yourself a nice little ridge with a warm
westerly, insect-laden wind, you may see them regularly during their summer
residency. If they're still there to see.

best wishes
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