Herons are usually seen in singular. I recently counted 10, yes 10, fly over me in straight line formation (well, a little squiggly) and high up. The squawk is unmistakable, the shape and wing flap as well. I have seen four or five together before this sighting.
This morning I shot this photo of a single blue on a perch along my pier. Once disturbed, three blues went a flying. The others were out of my sight.