We generally distinguish a swallow from the shape of its wings and the two points of its tail - but they are busy birds, and at speed they appear are a dark grey blur. When one stops for a moment, a different picture emerges.
In flight, they remain elusive. Here are a couple of shots from today, at high speed, and lots of blur.
I have called this a Welcome Swallow, rather than a Barn Swallow, because the wing linings appear grey rather than white and I cannot clearly make out a black band around the chestnut patch on the face.