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description of pigeon

description of pigeon

Description
The Common Ground Dove is among the smallest species in the family

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.[8] Smaller species tend to be known as doves, while larger species as pigeons, but no taxonomic basis distinguishes between the two.[8]

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.[9] 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 amongst the strongest fliers of all birds. They are also highly maneuverable in flight.
The Common Indian Dove mostly seen in the Villages of India

The plumage of the family is variable. Granivorous species tend to have dull plumage, with a few exceptions, whereas the frugivorous species have brightly coloured plumage.[8] The Ptilinopus fruit doves are some of the brightest coloured pigeons, with the three endemic species of Fiji and the Indian Ocean Alectroenas being amongst the brightest coloured. Pigeons and doves may be sexually monochromatic or dichromatic. In addition to bright colours, pigeons may sport crests or other ornamentation.

Like some other birds, Columbidae have no gall bladders.[10] Some medieval naturalists concluded they have no bile (gall), which in the medieval theory of the four humours explained the allegedly sweet disposition of doves.[11] In fact, however, they do have gall (as Aristotle already realised), which is secreted directly into the gut.[12]
Distribution and habitat
See also: List of Columbiformes by population
The Common Bronzewing has a widespread distribution across all of Australia and lives in most habitat types except dense rainforest and the driest deserts.

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.

The family has adapted to most of the habitats available on the planet. The largest number of species is found in tropical forests and woodlands. These species may be arboreal, terrestrial or semiterrestrial. Various species also inhabit savannas, grasslands, deserts, temperate woodlands and forests, mangrove forests, and even the barren sands and gravels of atolls.
The Zebra Dove has been widely introduced around the world.

Some species have large natural ranges. The Eared Dove ranges across the entirety of South America from Colombia to Tierra Del Fuego, the Eurasian Collared Dove has a massive (if discontinuous) distribution from Britain across Europe, the Middle East, India, Pakistan and China, and the Laughing Dove across most of sub-Saharan Africa, as well as India, Pakistan and the Middle East. Other species have a tiny, restricted distribution; this is most common in island endemics. The Whistling Dove is endemic to the tiny Kadavu Island in Fiji, the Caroline Ground-dove is restricted to two islands, Truk and Pohnpei in the Caroline Islands, and the Grenada Dove is restricted to Grenada in the Caribbean. Some continental species also have tiny distributions; for example, the Black-banded Fruit Dove is restricted to a small area of the Arnhem Land of Australia, the Somali Pigeon is restricted to a tiny area of northern Somalia, and Moreno’s Ground Dove is restricted to the area around Salta and Tucuman in northern Argentina.[8]

The largest range of any species is that of the Rock Dove. This species had a large natural distribution from Britain and Ireland to northern Africa, across Europe, Arabia, Central Asia, India, the Himalayas and up into China and Mongolia. The range of the species increased dramatically upon domestication, as the species went feral in cities around the world. The species is currently resident across most of North America, and has established itself in cities and urban areas in South America, sub-Saharan Africa, Southeast Asia, Japan, Australia and New Zealand. The species is not the only pigeon to have increased its range due to the actions of man; several other species have become established outside of their natural range after escaping captivity, and other species have increased their natural ranges due to habitat changes caused by human activity.[8]
Behaviour and ecology
The White-bellied Green Pigeon feeding on fruit

Seeds and fruit form the major component of the diets of pigeons and doves. In fact, the family can be divided into the seed-eating or granivorous species (subfamily Columbinae) and the fruit- and mast-eating or frugivorous species (the other four subfamilies). The granivorous species typically feed on seed found on the ground, whereas the frugivorous species tend to feed in trees. There are morphological adaptations that can be used to distinguish between the two groups, granivores tend to have thick walls in their gizzards, whereas the frugivores tend to have thin walls. In addition, fruit-eating species have short intestines, whereas those that eat seeds have longer ones. Frugivores are capable of clinging to branches and even hang upside down to reach fruit.[8]

In addition to fruit and seeds, a number of other food items are taken by many species. Some, particularly the ground-doves and quail-doves, take a large number of prey items such as insects and worms. One species, the Atoll Fruit Dove is specialised in taking insect and reptile prey. Snails, moths and other insects are taken by White-crowned Pigeons, Orange Doves and Ruddy Ground Doves.[8]

An unusual behaviour in a Rock Dove has been reported as it attempts to mate with a dead bird.[13]
Status and conservation
The Socorro Dove is extinct in the wild.

While many species of pigeons and doves have benefited from human activities and have increased their ranges, many other species have declined in numbers and some have become threatened or even succumbed to extinction. Amongst the 10 species to have become extinct since 1600 (the conventional date for estimating modern extinctions) are two of the most famous extinct species, the Dodo and the Passenger Pigeon.

The Passenger Pigeon was exceptional for a number of reasons.It is the only pigeon species to have gone extinct in modern times that was not an island species. It was once the most numerous species of bird on Earth. Its former numbers are difficult to estimate, but one ornithologist, Alexander Wilson, estimated one flock he observed contained over two billion birds. The decline of the species was abrupt; in 1871, a breeding colony was estimated to contain over a hundred million birds, yet the last individual in the species was dead by 1914. Although habitat loss was a contributing factor, the species is thought to have been massively overhunted, being used as food for slaves and, later, the poor, in the United States throughout the 19th century.

The Dodo, and its extinction, was more typical of the extinctions of pigeons in the past. Like many species that colonize remote islands with few predators, it lost much of its predator avoidance behaviour, along with its ability to fly. The arrival of people, along with a suite of other introduced species, such as rats, pigs, and cats, quickly spelled the end for this species and all the other island forms that have become extinct.

Around 59 species of pigeons and doves are threatened with extinction today, about 19% of all species.[14] Most of these are tropical and live on islands. All of the species are threatened by introduced predators, habitat loss, and hunting, or a combination of these factors. In some cases, they may be extinct in the wild, as is the Socorro Dove of Socorro Island, Mexico, which was driven to extinction by habitat loss and introduced feral cats.[15] In some areas, a lack of knowledge means the true status of a species is unknown; the Negros Fruit Dove has not been seen since 1953, and may or may not be extinct, and the Polynesian Ground Dove is classified as critically endangered, as whether it survives or not on remote islands in the far west of the Pacific Ocean is unknown.

Various conservation techniques are employed to prevent these extinctions, including laws and regulations to control hunting pressure, the establishment of protected areas to prevent further habitat loss, the establishment of captive populations for reintroduction back into the wild (ex situ conservation), and the translocation of individuals to suitable habitats to create additional populations.

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