The largest of our cowbirds, the bronzed has a rather sinister appearance thanks to the male’s typically hunchbacked look and bloodred eye. It gives an odd hovering display that is unique. Polytypic. Length 8.7".

A thick-set cowbird with a large and deep black bill. Males in particular may look proportionately small headed, especially when ruffling the nape feathers in display. Legs black. Adult male: entirely black with bronzed body iridescence, becoming blue-green on wings and tail. Eyes bright red. Adult female: varies geographically. More widespread eastern subspecies has a black female plumage, lacking strong gloss, with browner wings and tail. Eyes red. Juvenile: similar to female but dark brown.

Four subspecies recognized, 2 in North America: the more widespread aeneus,