JC Penney has this cool faux-fur vest for that can be incorporated into lots of animal Halloween costume ideas: I can’t tell from the pic, but I am assuming the belt is removable if desired. They are not usually secured.
For an EAGLE: Layer this vest on top of a long brown dress from the thrift store, cut it into a high-low hem and trim the hem in a white/black feather boa. For a boy, dye a white long john set brown, and layer the vest over the top. Add brown boots and make or purchase a felt or feathered eagle mask along with eagle wings on Amazon.