Well, what do you know?

Posted May 6th, 2010 by kcorliss. Comment (0).

Vaux’s swift is a somewhat enigmatic bird mostly due to its nest site choice. Usually it’s in hollow trees of deeply forested areas of the Northwest. I’ve seen them in Idaho and Washington. They’re basically the western counterpart to the much more visible chimney swift we have in the east. In fact they look so much alike I sometimes wonder if we don’t get a Vaux’s swift on occassion but no one can tell the difference.

Anyway, I didn’t realize Vaux’s swifts also roosted in chimneys. That is, until I read this story from the LA Times. It describes a huge group of migrant swifts (estimated at “tens of thousands”) using one particular old chimney in downtown L.A., at the Chester Building. That must have been astounding to see.

The odd locale is believed to be one of the most populous roosting sites for the birds in North America, local avian experts said.

Just how weird was this gathering? Here’s an Audobon guy named Larry Schwitters:

“In the heart of one of the world’s great steel-and-asphalt jungles, a great wildlife migration is underway,” Schwitters, of Issaquah, Wash., said in a telephone interview. “Sites with more than 10,000 Vaux’s swifts are very rare. There are only about six of them in the world.”

I love these wildlife spectacles, whether it’s caribou, snow geese, whatever. Huge numbers are just downright cool to witness. Wish I’d have been there.

Like the raptors which seem to follow large migrant goose flocks and wolves which trail the caribou, any time you mass this many organisms in one place another organism a step up on the food chain usually is usually well aware.

About 7:20 p.m., the birds began funneling down the chimney. Hungry ravens were waiting for them, using their beaks to snag birds out of the air as they plunged into the chute.

I wonder if the ravens were targeting individual birds (quite a feat I imagine, swifts don’t get their names for slowness) or merely diving through the flock with beaks open. It doesn’t say.

In any case the birds will be out of L.A. in due time and meander up to their nesting grounds. But someday I’d sure like to see this mass grouping.

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