Vaux’s Swift monitoring hits its tenth year
By Michael Helm
This fall, for the 10th consecutive year, Golden Gate Bird Alliance members monitored the number of migrating Vaux’s Swifts spending the night in the chimneys of McNear Brick & Block brickyard in San Rafael.
Vaux’s Swifts are West Coast birds with a long migration: Some travel as far as 4,000 miles from the Alaska panhandle to Panama. Like swallows, they catch insects on the fly with fast, graceful swoops. Unlike swallows, they can’t perch. They sleep by clinging to rough vertical surfaces, using their tail as a kickstand. They roost communally, with thousands of swifts—sometimes even tens of thousands—cramming together for warmth and safety inside hollow trees and old brick chimneys.
Vaux’s Swifts enter a chimney at McNear Brickyard / Photo by Michael Helm
Vaux’s Swift / Photo by Bettina Arrigoni
Swifts roosting en masse in a Washington state chimney / Photo courtesy of Larry Schwitters
Birders in Washington state began documenting Vaux’s Swift roosts there in the early 2000s, in part to preserve the old chimneys needed by the birds. But the swifts’ other migratory stopping points remained a mystery.
Then, in 2010, Golden Gate Bird Alliance birding instructor Rusty Scalf discovered a major Vaux’s Swift roost in the Bay Area—the chimneys of McNear Brick & Block in San Rafael.
While the plant workers and the McNear family were well aware of some kind of occupation of the long-decommissioned chimneys, it wasn’t until Rusty stumbled on the site that the “occupiers” were identified as Vaux’s swifts (and not some kind of confused bat).
Since then, GGBA members have shown up assiduously just before sunset for two months each fall to count the swifts, in coordination with Larry Schwitters’ “Vaux’s Happening” regional observation project. It takes concentration, a good scope, and a quick hand on a clicker for counting: The sky around the chimneys can shift from open blue to a black swarm of diving and circling swifts at a moment’s notice.
McNear Brickyard / Photo by Michael Helm
Looking for swifts as sunset approaches / Photo by Michael Helm
The southbound migration typically runs from around August 15 to mid-October. This year’s Vaux’s Swift count season closed on October 23, when sunset came and went with no swifts.
GGBA and Marin Audubon led one public field trip apiece in mid-September, at the height of the migration, courtesy of McNear Brick and Block and its proprietor, Dan McNear.…

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