The center bird is an Anginga, the other birds on either side are Cormorants. The photograph is surprisingly not on the open water. This was off near a smaller pond. These birds are all divers but I guess it was less chaotic away from the rookeries.
Alligators can shake the ground with their deep rumbles. Prehistoric is the only way to describe it.
Swamps actually get louder once night falls. Small frogs and night birds being the culprits, except for the big locals.