You can see the baby poking its head out of the hole. The colony was being attacked by starlings (one poked his head into the nest). I can’t decide whether these are Tree Swallows or Violet-green Swallows. One had a clear stripe above the eye, which indicates the latter; the blue black and the liquid notes included in the call indicate the former; on the other hand, Tree Swallows are meant to be further north at this time of year, and supposedly nest near water(!). I’ll look again later today.