‘Cultural’ stopover

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

(Note: ‘Cultural’ in the headline is a reference to navigator-speak aboard B-52s in the mid-1980s. They used prominent landmarks painted by their radars to update and “tighten” navigation systems for more accurate bombing. Ones such as a bend in a large river or a point of land in a lake were natural. Dams, water towers, or other man-made structures, though, were known as ‘cultural.’ At least that’s what they told us pilots. What did we know?)

The list of major staging sites for migrant birds is not all that long. We’ve all heard of the well known ones–Platte River, Grey’s Harbor, Sand Lake, the Salton Sea. What about lesser ones? Sand Lake, check; Horicon Marsh, check; Chapman School…Chapman School? Yup.

Months ago I mentioned a location in downtown Los Angeles which was a major spring staging area for Vaux’s swifts. Thanks to my Oregon connection (cousin Bill), it has come to my attention that there is perhaps an autumn counterpart to it in Portland. That’s where Chapman School comes in.

vaux's swifts entering a roost site

According to the Portland Audubon Chapter’s website, as many as 35,000 swifts have been reported streaming into the school’s chimney at sunset, an amazing number. They say the scenario will repeat itself every night at least through the end of September when the birds will continue their migration toward Middle America.

The speed with which these tiny birds go zipping into nightly roost sites is nearly unbelievable.

To add to the quandary, consider this: The dramatic spiral the birds take into a chimney at night is accomplished nearly en masse; an avian tornado. How in the world the Vaux’s (pronounced vawks, not vohs) swifts sort each other out without crashing into one another is indeed one of those facts we have to just sit back and relish. One of God’s gifts.

I’ve not seen a similar case in our area but there might be one. I just haven’t heard about it. Of course for us it would be chimney swifts not Vaux’s. Anyone in the Northland ever witness big numbers of roosting chimney swifts? I like to hear about it if you have. I don’t mean tens, I means thousands.

kcorliss@forumcomm.com

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