It appears to be an "American Bittern."
. . . but I scared him off when I walked up on him.
When I was a kid, we had lots of them around the lakes in Northern Wisconsin. I don't know how many times I got with a few feet of a bittern before it would decide to wildly bob its head and take off from the tall reeds where I'd be fly fishing for bass or bluegill. "Startled" hardly describes the sensation.
They make neat sounds. Kind of like someone taking a big "glug" out of a moonshine jug.
