Pigeons are stout-bodied birds

• published: 24 Sep 2014
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Pigeons and doves constitute the bird clade Columbidae, that includes about 310 species. Pigeons are stout-bodied birds with short necks, and have short, slender bills with fleshy ceres. They 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. Pigeon 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 feral rock pigeon, common in many cities. Doves and pigeons build relatively flimsy nests – often using sticks and other debris – which may be placed in trees, ledges, or, on the ground, depending on species. They lay one or two eggs, and both parents care for the young, which leave the nest after seven to 28 days. Unlike most birds, both sexes of doves and pigeons produce "crop milk" to feed to their young, secreted by a sloughing of fluid-filled cells from the lining of the crop. Young doves and pigeons are called "squabs". Pigeons and doves exhibit considerable variations in size. The largest species is the crowned pigeon of New Guinea, which is nearly turkey-sized, at a weight of 2–4 kg (4.4–8.8 lb) The smallest is the New World ground-dove of the genus Columbina, which is the same size as a house sparrow and weighs as little as 22 g.[8] With a total length of more than 50 cm (19 in) and weight of almost 1 kg (2 lb), the largest arboreal species is the Marquesan imperial pigeon, while the dwarf fruit dove, which may measure as little as 13 cm (5.1 in), has a marginally smaller total length than any other species from this family.Smaller species tend to be known as doves, while larger species as pigeons, but no taxonomic basis distinguishes between the two. Overall, the Columbidae tend to have short bills and legs, and small heads on large compact bodies. Their characteristic head bobbing was shown to be due to their natural desire to keep their vision constant in a 1978 experiment by B. J. Frost in which they were placed on treadmills – they did not bob their heads as their surroundings were constant.The wings are large and have low wing loadings; pigeons have strong wing muscles (wing muscles comprise 31–44% of their body weight) and are among the strongest fliers of all birds. They are also highly manoeuvrable in flight. Pigeons and doves are distributed everywhere on Earth, except for the driest areas of the Sahara Desert, Antarctica and its surrounding islands and the high Arctic. They have colonised most of the world's oceanic islands, reaching eastern Polynesia and the Chatham Islands in the Pacific, Mauritius, the Seychelles and Réunion in the Indian Ocean, and the Azores in the Atlantic Ocean. Source : http://en.wikipedia.org/wiki/Columbidae