Pigeons and doves are stout-bodied birds with short necks, and short slender bills and in some species, these bills feature fleshy ceres. They primarily feed on seeds, fruits, and plants. This family occurs worldwide, but the greatest variety is in the Indomalaya and Australasi ecozones. In general, the terms "dove" and "pigeon" are used somewhat interchangeably. Pigeon is a French word that derives from the Latin pipio, for a "peeping" chick, while dove is a Germanic word that refers to the bird's diving flight. 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 rock dove, one subspecies of which, the domestic pigeon, is common in many cities as the feral pigeon. Pigeons and doves are likely the most common birds in the world.