Hi Ferguson
This looks like a Yellow-crowned Night-Heron immature.
The Black CNH has a more sharp bill and yellowish eye, this one instead has an orange eye.
So is this a black? I shot this in a series expecting him to be lunch, the alligator was walking to the left, he was walking to the right, they passed quite close and both ignored the other.
But I wasn't sure what he was. He looks like a heron, but not the right shape.
Or is it an immature green (but pretty large for on to be immature).
I'm not sure the eye is the right color, I had a fill flash on and the purple center I am pretty sure is flash burn, but not sure abou tthe reddish area around. I've looked at it at high magnification and not sure.