These birds are fairly secretive and rely on camouflage feathering to blend into the marsh to conceal them from predators. They make a loud "glugging" noise during the breeding season that sounds like a boot being pulled out of mud. This male was standing right along the edge of a road, calling to his prospective mate on the other side. The birds lose their decorative wing patches after mating; this is the first time I've ever seen a bittern in this plumage.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/69803582@N00">Steve Deger</a>
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/69803582@N00/119285711/">American Bittern, Itasca Cty, MN</a>