My bet is they roosted right where you found them, in the cypress pond. I don't think they roost in trees, ...but can be wrong. Gonna research that.
I had a weird morning. The woodies usually fly in around first light (flooded cypress) but they didn't. They were already there, I think maybe they swam in from roosting in live oaks at the edge???? Called with several off and on. One got up within range all of a sudden but I wasn't quick enough. I also had one swim too me and then start swimming in circles and calling like crazy! About 20 yards out. Called for a solid minute then flew off. I just watched him, never have seen one do that before.They’ve been flying out to roost really early this week. 5:30pm has been prime time as they’re headed out, but I’m not hunting roost holes.