I saw this beauty along the Mill Race Path in a riparian area. There was a number of them zooming back and forth above the water, too fast for this old guy to catch them. But then I didn't have my Nikon D500 DSLR, which could stop them in their tracks. Still, they are very fast. I think they were swallows, but this one confused me. Whatever it is, I enjoyed the antics. A friend ID'd the bird, a Northern Rough-winged Swallow. See - http://www.audubon.org/field-guide/bird/northern-rough-winged-swallow