An idea for a potential animal for the salt marshes: a heron lookalike.
ThomasRuz: Added sketch
Kevaar: added two rough sketches. Since first picture does not make it clear, the second is a closeup of the creature's wing. They can't fly, the "feathers" are in actuality talons (the red thing on its neck is a dewlap, not one of the wings). The things on its back are fins, similar to the spines of the Nazgul from LOTR. The creatures probably use these in mating or territorial displays.