Last weekend I witnessed, and sketched, one of the minor miracles of bird migration in the Bay Area: the Vaux’s swifts of McNeer’s brickyard in Marin County. Every September or early October these bat-like birds arrive in, first hundreds and then thousands, to roost for the night in the three abandoned brick smoke stacks at the brickyard. They (or perhaps other birds) stay for a few weeks and then disappear, their next destination is still a mystery. We know that they winter in Mexico and Central America.
We arrived at around 7:00 PM and the persistent calls drew our eyes skyward to pick out the high flying birds that covered the sky like floating ash. The ash cloud spiraled downward into the left smoke stack and nature was giving us a truly wonderful sight as the birds replicated watching a film of smoke rising from the stack but being shown in reverse. We joined the crowd of birders, biologists, and locals. The previous evening, biologists had counted an incredible 19,685 swifts! Tonight the count was slightly below that but just as impressive at 16,300 birds, 15,700 of which were roosting in the left stack alone (which is the stack I sketched). We missed the peak of migration by one day.
My previous visit to see the swift migration was September 25, 2012. The count on that day was a measly 8,200, almost half of the total seen this evening. In this journal page I noted that Roger Tory Peterson called these swifts “a cigar with wings”.