The Bronzed Cowbird is smaller and shorter-tailed than blackbirds and grackles and has a more conical bill. Bronzed Cowbird is similar to female Brown-headed Cowbird but has red eyes and is slightly larger with a longer bill.
Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.