Found in southwest Michigan. It appears to have fallen from a nest.
The body shape does seem to indicate it's some kind of heron/egret (12 species, of which, have been previously found in Michigan [according to Wikipedia]).
The seemingly large size from your picture (please edit with actual or best approximation of size), the tufted feathers on the head, white face, and the start of a black line on the anterior edge of the eye all suggest that this could be a great blue heron.
Great blue herons are typically grey (not the dark almost black of your specimen), but I did find some photos with nestlings /fledglings with darker plumage, including below: