Recently while enjoying Screamin' Mimi's ice cream with Kathy Spalding, our neighbor who we first met while walking our respective dogs and have over the years spent more time with, mentioned biking into Sebastopol each evening to count swifts. Both Dwight and I were so enthralled with her stories I thought perhaps you all would enjoy a guest blog post by her. As you read her informative and fun post
Perhaps you’ve seen the Vaux’s Swifts at Healdsburg’s Rio Lindo Academy during their autumn migration. Last year my pal Donna made the trip to enjoy the spectacle when someone mentioned the swifts on Sebastopol’s High Street.
You guessed it. Donna lives on High Street.
And so do the swifts, for a few weeks anyway. Since late August they’ve been dropping into the chimney of a private residence on Calder at High Street, but not before treating lucky on-lookers to jaw-dropping displays.
Around dusk, the swifts start out flying fairly high up in a loose group, in that seemingly effortless “twinkling” flight described in field guides. Gradually the group becomes denser, more organized, a feathery tornado not unlike a starling cloud.
On evenings when the numbers are high, the birds become a whirling cylinder. Flying at high rate of speed, the swifts create a whirring sound punctuated with the occasional tap of impact when wing meets wing. This cylinder of swifts takes position over the chimney. Then individuals peel away from the group and pour into the chimney. An onlooker described it as smoke in reverse.
Vaux’s Swifts are perfectly designed for what they do. Weighing in at 15 to 22 grams (equivalent to 3 or 4 quarters) with 12-inch wingspans, these wee birds cover huge distances, migrating as far as Canada to Venezuela. Each spends the day gorging on thousands of mosquitoes and other aerial arthropods. Mouth as wide as the face, maximizing food intake in flight, like baleen whales in the sky. Tiny feet sewn on sideways for grasping rough vertical surfaces. Spiked tailfeather tips for propping, much like a woodpecker. Flat forehead for an aerodynamic profile. Wings with short “arms” and long “fingers” for speedy flight. Vaux’s cousins the Common Swift, Apus apus, holds the level flight speed record at just under 70 miles per hour. (The peregrine has been clocked at higher diving speeds, but that’s working with gravity.)
Swifts resemble swallows, but they’re closest relatives are nightjars and hummingbirds, with whom they share the ability to enter torpor, dropping their body temperature to conserve energy. Other birds do this, but none as dramatically.
Aristotle theorized that some birds hibernated, burrowed in mud, to explain their absence in winter. The truth of migration is stranger still, but swifts raise the bar to an entirely new mind-blowing level. Few things are as aerial as swifts. Some species remain airborne for months at a stretch. Apus apus is said to spend the first three years of its life flying. Eating, mating, sleeping, it all takes place during flight. They even practice aerial roosting. They will ascend to a great height (and have been found at 10,000 feet) and use wind direction to orient themselves. Birds have been shown to shut down half their brains, which is thought to allow for sleep.
Vaux’s swifts used to rely on old-growth forests for nesting and roosting. With the thinning of snags and decimation of forests, swifts increasingly rely on chimneys. Due to earthquake and other concerns, swift-friendly chimneys are harder to find.
Not enough is known about these fascinating birds. To learn more, and to report your sightings, see www.vauxhappening.org/Vauxs_Happening_Home.html.