Thursday, September 04, 2008

Barn Swallows on radar in Oregon

This morning (Sept. 4) I captured this image from the doppler radar when the spreading cloud of Barn Swallows (the green bubble in the center) was about to disperse throughout this part of the Willamette Valley. By now we know that they, or others like them, will reassemble in the same place and do this again tomorrow morning, and probably every morning into early October.

Bruce Cousens, a biologist watching this action from Vancouver Island in B.C., is hoping we might find migrating Purple Martins joining the roosting Barn Swallows. He also points out that there are several smaller "bubbles" of green visible briefly in the area near Forest Grove in Washington County about 30 miles north of the major flock in Yamhill County. I hope some birders in that area might begin watching "their" cornfields just before sunset. It would be interesting to know that there are other locations where this spectacle can be observed, and that these birds are not totally dependent on one location.

2 Comments:

At 8:57 AM, Anonymous Don M said...

There's a piece in Sacramento Bee today about tree swallows roosting in cornfield near Tracy, Ca. It says tree swallow flocks are only ones large enough to be seen on radar.
Does this happen often?

 
At 10:24 PM, Blogger FS said...

Thanks for your comment. Apparently the writer of that comment did not notice that the Barn Swallow flock up here in Oregon (which I first found 11 years ago) has been watched on NEXRAD radar for the past several years by Bruce Cousens, the same researcher who called attention to the telltale radar image near Tracy. This kind of flocking apparently happens every year, but it has been noticed in very few locations.

 

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