The fox sparrow (Passerella iliaca) is a large American sparrow. It is the only member of the genus Passerella, although some authors split the genus into four species (see below).
Adults are amongst the largest sparrows, heavily spotted and streaked underneath. All feature a messy central breast spot though it is less noticeable on the thick billed and slate-colored varieties. Plumage varies markedly from one group to another. source