To see a really cool wildlife spectacle right now in Yakima, all you have to do is wait until, say, 30 minutes before sunset and drive to ... downtown.

That’s right: downtown. Specifically, the parking lot behind Johnson’s Auto Glass (119 S. 1st Street). As sunset nears, look west to the building’s old chimney, where this spectacle will take place:

Small dark birds, Vaux’s (rhymes with foxes) swifts will be darting through the sky in a loose flock, many of them uttering a sharp, twittering call. Eventually one or two of the birds will dive down the chimney at breakneck speed and then — as if a starting gun has been fired, a mass of swirling birds in the shape of a tornado plunge into the chimney.

In recent nights, birders have counted upwards of 1,400 swifts plunging into this chimney to roost for the night. It’s an annual phenomenon that takes place only during their seasonal migration, as they will huddle together to conserve body heat for their long flight south for the winter.

And seeing them funnel by the hundreds into the chimney is, indeed, quite a spectacle.

HOW TO SPOT ONE: Vaux’s swifts are dark-colored birds of the open sky that resemble swallows as both fly about, snatching insects in the air. Swallows, though, have angled wings and fly with slower, fluttering wing beats. Swifts, by contrast, are shaped like a cigar with wings, with scimitar-shaped wings that give it a drawn-bow appearance. Their wing beats are stiff and more rapid than a swallow as they zip this way and that in pursuit of prey.

FAVORITE HANGOUT: Vaux’s swifts are seen spring and fall over Yakima. Their summer nesting grounds are mainly in mature forests of the Pacific Northwest conifer belt. They seek cavities in large trees, either a conifer, cottonwood or Oregon white oak. A handful of Yakima Valley birds may use chimneys, while further west you can see them in the tall trees of the Oak Creek Wildlife Area.

CHOW TIME: Swifts consume tiny flying insects and so this bird times its arrival hereabouts in spring to the beginning of warmer weather, usually after about April 20. During cold snaps, these birds search for scarce flying insect by foraging very low over the water surface of a river or lake.

COURTSHIP: These birds engage in a lot of chasing behavior, sometimes with their wings held in that distinct “V” shape. Swifts are the only birds that routinely mate while flying, tumbling toward the ground, separating only as they approach the ground.

FAMILY MATTERS: Swifts seek out cavities dug by woodpeckers or hollows in trees, in which the female will lay three to six eggs. Incubation is by both parents for 18 to 20 days. Both parents feed the youngsters a “bolus,” a compact ball of partially digested insects held in the bird’s esophagus, about every 15 minutes. The young fledge in 27 to 32 days, a long period for such as a small bird.

WHAT’S IN A NAME: This species is named after William Sanson Vaux, a 19th-century Philadelphia naturalist. Its scientific name, Chaetura vauxi, is an apt description: Chaetura has a Greek origin meaning “spine-tailed,” and these spines aid the bird in clinging to vertical surfaces.

NOT TO BE CONFUSED WITH: The closely-related chimney swift, which typically ranges east of the Rocky Mountains, lives up to its name and inhabits chimneys. This familiar bird of towns and open places regular nests and roosts in these manmade structures. The swifts have found these a ready substitute for natural cavities once provided by the vast deciduous forest that historically covered much of America’s Northeast. As much of that forest was felled by expanding settlement, chimneys became the “cavities” of choice for the chimney swift.

The western Vaux’s swift has not made this switch to artificial structures in a big way. It still nests mostly in holes in big trees, especially cavities excavated by woodpeckers. However, between their wintering grounds in southern Mexico and their nesting grounds in the Pacific Northwest, Vaux’s swifts often seek chimneys to roost in at night.

WANT TO KNOW MORE? Larry Schwitters, an enthusiastic western Washington swift watcher, has done much to promote awareness of the Vaux’s swift and their migrations. Check out www.vauxhappening.org, which has videos of birds coming to their roosts and data on the timing and numbers of birds. Because old chimneys are routinely razed, Larry’s website draws attention to these threats. Public awareness of these threats has actually galvanized support to preserve these structures where possible.

• Wildlife Moment, focusing on native wildlife, typically runs in Outdoors on the first Tuesday of every month, with the cooperation of the Yakima Valley Audubon Society.