Columbidae is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with small heads, relatively short necks and slender bills that in some species feature fleshy ceres. They feed largely on plant matter, feeding on seeds (granivory), fruit (frugivory), and foliage (folivory). In colloquial English, the smaller species tend to be called "doves", and the larger ones "pigeons", although the distinction is not consistent, and there is no scientific separation between them. Historically, the common names for these birds involve a great deal of variation. The bird most commonly referred to as "pigeon" is the domestic pigeon, descendant of the wild rock dove, which is a common inhabitant of cities as the feral pigeon. Columbidae contains 52 genera divided into 353 species. The family occurs worldwide, often in close proximity to humans, but the greatest diversity is in the Indomalayan and Australasian realms. 118 species (34%) are at risk, and 13 are extinct, with the most famous examples being the dodo, a large, flightless, island bird, and the passenger pigeon, that once flocked in the billions.