I had a similar experience yesterday (August 1) at about 6:20 p.m. in Longmont, Boulder County. A loose flock of Common Nighthawks (similarly, at least ten individuals) was swirling around over the intersection of 17th Ave and Hover St as I approached it on my way home from work. I quickly pulled over into the Safeway parking lot for a better look, but they were gone almost as soon as I had gotten out of the car, moving off toward the southwest. What a cool thing to see!
Sarah Spotten
Longmont, CO