Appeared to be a juvenile. Would have fit in the palm of my hand.
Observed over a period of 30-40min, time listed is of beginning of observation. Observed pair of rat snakes invade a tree swallow nest and eat (presumably) the eggs inside (no chirps heard). The pair of tree swallows watched on from a nearby branch and got increasingly agitated.
After eating the pair of snakes emerged from the nest, proceeded to mate, and then returned into the swallow's nest.