It wasn't a "plume" of feathers, it was more of an explosion. When I used to work in Portland, there was a pair of Peregrine Falcons nesting under the Fremont bridge. There is a grain elevator next door, and so a LOT of pidgeons. The Falcons would circle so high that they could hardly be seen, and then one would come down at a kamikaze suicide speed, and BOOM would go a pidgeon. Always amazed me that the Falcon could survive the collision, and still snag the remains of the pidgeon before it hit the river. Sometimes, you'd just hear it go "smack", turn around to look, and there would be a cloud of feathers.
