what kind of bird? We live in Michigan

(Harrison Township Mi)

Seen this on our dock this morning. i have looked up several birds and i haven't found out what it is yet. We live in Michigan. One hour north of Detroit.Somebody said it was a Bittern but the pictures i have found online on Bittern's are brown color. ?? Help

Comment
It's not a Bittern. They hang out in reeds, and their voice sounds like a toilet plunger. I think your photo is that of a Black-crowned Night Heron.
Susan