Pigeons and doves includes some 310 species. They are stout-bodied birds with short necks, and have short, slender bills with fleshy ceres. Doves feed on seeds, fruits, and plants. This family occurs worldwide, but the greatest variety is in the Indomalaya and Australasia ecozones. In general, the terms "dove" and "pigeon" are used somewhat interchangeably. In ornithological practice, "dove" tends to be used for smaller species and "pigeon" for larger ones, but this is in no way consistently applied, and historically, the common names for these birds involve a great deal of variation between the terms. The species most commonly referred to as "pigeon" is the Feral Rock Pigeon, common in many cities.