Barn Swallow flock staging in Oregon

Once again the huge flock of Barn Swallows (which forms every year at this time here in Yamhill County, Oregon) is staging a repeat performance. Current thinking is that this gathering likely represents a significant percentage of the Barn Swallow population of northwestern North America. It's impossible to count so many birds spread over several square miles, but when they come together in a "hurricane" swirl over a large cornfield, and then take an hour to plunge down into it to find a nighttime roost, it becomes obvious that there are several hundred thousand birds involved, and perhaps more than that. The photo shows only a small section of the entire flock, but gives some idea of the spectacle that is repeated here nightly for about a month every fall. (Click on the photo for an enlarged view.)