Hi all, Yesterday, while waiting for fellow birder Tim Boucher at the bridge to Roosevelt Island in DC, I saw something I'm not quite sure what to make of it... Barn Swallows are building nests below the bridge that crosses over the Potomac to Roosevelt Island. After skittering over the water, searching for insects, the Swallows formed into a group and headed in the direction of Rosslyn about 30 feet above treetop. A few seconds later, a Peregrine Falcon came from the direction the Swallows were heading, crossing over the Potomac. Immediately following the Peregrine was the group of Barn Swallows. They weren't mobbing the Peregrine like crows mob hawks, but the definitely seemed like they were trying to drive the Peregrine away. Half way down the island the Barn Swallows returned to their nesting area. Has anyone experienced anything like this? Is this a common defensive behavior for Swallows? Any help would be appreciated. Lou Shomette Columbia, MD PS We had several Wood Thrush, Veery and Eastern Towhees. Lots of Yellow-rumped Warblers, Northern Parula, Ovenbird and a Scarlet Tanager. Also, my first Hummingbird Clearwing moth of the year.