Rock dove

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Rock dove
Columba livia Baltasound Shetland 1.jpg
Group of wild birds in Shetland, Scotland
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Columbiformes
Family: Columbidae
Genus: Columba
Species:
C. livia
Binomial name
Columba livia
Gmelin, JF, 1789 [2]
Columba livia distribution map.png
  approximate native range
  introduced non-native populations

The rock dove, rock pigeon, or common pigeon ( /ˈpɪ.ən/ also /ˈpɪ.ɪn/ ; Columba livia) is a member of the bird family Columbidae (doves and pigeons). [3] :624 In common usage, it is often simply referred to as the "pigeon", although this is the wild form of the bird; the pigeons most familiar to people are the domesticated form of the wild rock dove.

The domestic pigeon (Columba livia domestica, which includes about 1,000 different breeds) descended from this species. Escaped domestic pigeons have increased the populations of feral pigeons around the world. [4]

Wild rock doves are pale grey with two black bars on each wing, whereas domestic and feral pigeons vary in the colour and pattern of their plumage. Few differences are seen between males and females; i.e they are not strongly sexually dimorphic. [5] The species is generally monogamous, with two squabs (young) per brood. Both parents care for the young for a time. [6]

Habitats include various open and semi-open environments where they are able to forage on the ground. Cliffs and rock ledges are used for roosting and breeding in the wild. Originating in Southern Europe, North Africa, and Western Asia, pigeons have become established in cities around the world. The species is abundant, with an estimated population of 17 to 28 million feral and wild birds in Europe alone and up to 120 million worldwide. [1] [7]

Taxonomy and systematics

In Iran, reflecting its adaptation to cliff-like perches Kabootar Kordestan.jpg
In Iran, reflecting its adaptation to cliff-like perches
In India Rock Pigeon Columba livia.jpg
In India

The official common name is rock dove, as given by the International Ornithological Congress. [8] The rock dove was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Systema Naturae written by Carl Linnaeus. He placed it with all the other doves and pigeons in the genus Columba and coined the binomial name Columba livia. [9] The genus name Columba is the Latin word meaning "pigeon, dove", [10] whose older etymology comes from the Ancient Greek κόλυμβος (kolumbos), "a diver", from κολυμβάω (kolumbao), "dive, plunge headlong, swim". [11] Aristophanes (Birds, 304) and others use the word κολυμβίς (kolumbis), "diver", for the name of the bird, because of its swimming motion in the air. [12] The specific epithet livia is a medieval Latin variant of livida, "livid, bluish-grey"; this was Theodorus Gaza's translation of Greek peleia, "dove", itself thought to be derived from pellos, "dark-coloured". [13] :228 Its closest relative in the genus Columba is the hill pigeon, followed by the other rock pigeons: the snow, speckled, and white-collared pigeons. [3] Pigeon chicks are called "squabs". [6] Note that members of the lesser known pigeon genus Petrophassa and the speckled pigeon (Columba guinea), also have the common namerock pigeon”. The rock dove was first described by German naturalist Johann Gmelin in 1789. [14] The rock dove was central to Charles Darwin's discovery of evolution, and featured in four of his works from 1859 to 1872. Darwin posited that, despite wide-ranging morphological differences, the many hundreds of breeds of domestic pigeon could all be traced back to the wild rock dove; in essence human selection of pigeon breeds was analogous to natural selection. [15]

Subspecies

Nine subspecies are recognised: [16]

Description

A distinctive operculum is located on top of the beak. Pigeon portrait 4861.jpg
A distinctive operculum is located on top of the beak.

Centuries of domestication have greatly altered the rock dove. Feral pigeons, which have escaped domestication throughout history, have significant variations in plumage. [17] When not specified, descriptions are for assumed wild type, though the wild type may be on the verge of extinction or already extinct. [18]

The adult of the nominate subspecies of the rock dove is 29 to 37 cm (11 to 15 in) long with a 62 to 72 cm (24 to 28 in) wingspan. [19] Weight for wild or feral rock doves ranges from 238–380 g (8.4–13.4 oz), though overfed domestic and semidomestic individuals can exceed normal weights. [3] [5] It has a dark bluish-grey head, neck, and chest with glossy yellowish, greenish, and reddish-purple iridescence along its neck and wing feathers. The iris is orange, red, or golden with a paler inner ring, and the bare skin round the eye is bluish-grey. The bill is grey-black with a conspicuous off-white cere, and the feet are purplish-red. Among standard measurements, the wing chord is typically around 22.3 cm (8.8 in), the tail is 9.5 to 11 cm (3.7 to 4.3 in), the bill is around 1.8 cm (0.71 in), and the tarsus is 2.6 to 3.5 cm (1.0 to 1.4 in). [3]

A medium sized flock forages Doves fighting.JPG
A medium sized flock forages

The adult female is almost identical in outward appearance to the male, but the iridescence on her neck is less intense and more restricted to the rear and sides, whereas that on the breast is often very obscure. [3]

The white lower back of the pure rock dove is its best identification characteristic; the two black bars on its pale grey wings are also distinctive. The tail has a black band on the end, and the outer web of the tail feathers are margined with white. It is strong and quick on the wing, dashing out from sea caves, flying low over the water, its lighter grey rump showing well from above. [20] [ self-published source? ]

Young birds show little lustre and are duller. Eye colour of the pigeon is generally orange, but a few pigeons may have white-grey eyes. The eyelids are orange and encapsulated in a grey-white eye ring. The feet are red to pink. [6]

White rock pigeon caught in Al-Maghtas, Jordan. WHITEDOVE.jpg
White rock pigeon caught in Al-Maghtas, Jordan.

The subspecies gymnocycla is smaller and very much darker than the nominate subspecies. It is almost blackish on the head, rump and underparts with a white back and the iridescence of the nape extending onto the head. Subspecies targia is slightly smaller than the nominate, with similar plumage, but the back is concolorous with the mantle instead of white. Subspecies dakhlae is smaller and much paler than the nominate. Subspecies schimperi closely resembles targia, but has a distinctly paler mantle. Subspecies palaestinae is slightly larger than schimperi and has darker plumage. Subspecies gaddi is larger and paler than palaestinae, with which it intergrades in the west. Subspecies neglecta it is similar to the nominate in size but darker, with a stronger and more extensive iridescent sheen on the neck. It intergrades with gaddi in the south. Subspecies intermedia is similar to neglecta but darker, with a less contrasting back. [3] :176–179

There have been numerous skeletal descriptions of the rock dove and the associated muscles including those of the eye, jaw, neck, and throat. [21] The skull is dominated by the rostrum, eye socket, and braincase. [21] The quadrate bone is relatively small and mobile and connects the rest of the cranium to the lower jaw. [21] The latter has an angled shape in side view because the long-axis of the front half of the lower jaw is at a 30° angle to the back half. [21] Beneath the skull, the hyoid skeleton involves three mid-line structures and a pair of elongate structures that stem from between the junction of the back two structures. [21] The anterior structure (the paraglossum or entoglossum) is unpaired and shaped like an arrowhead. [21]

In flight, British Columbia, Canada Rock dove - natures pics.jpg
In flight, British Columbia, Canada

When circling overhead, the white underwing of the bird becomes conspicuous. In its flight, behaviour, and voice, which is more of a dovecot coo than the phrase of the wood pigeon, it is a typical pigeon. Although it is a relatively strong flier, it also glides frequently, holding its wings in a very pronounced V shape as it does. [22] As prey birds, they must keep their vigilance, and when disturbed a pigeon within a flock will take off with a noisy clapping sound that cues for other pigeons to take to flight. The noise of the take-off increases the faster a pigeon beats its wings, thus advertising the magnitude of a perceived threat to its flockmates. [23]

Feral pigeons are essentially the same size and shape as the original wild rock dove, but often display far greater variation in colour and pattern compared to their wild ancestors. The blue-barred pattern which the original wild rock dove displays is generally less common in more urban areas. Urban pigeons tend to have darker plumage than those in more rural areas. [24]

Slow motion, demonstrating the wing movements

Pigeons feathers have two types of melanin (pigment)  eumelanin and pheomelanin. A study of melanin in the feathers of both wild rock and domestic pigeons, of different coloration types and known genetic background, measured the concentration, distribution and proportions of eumelanin and pheomelanin and found that gene mutations affecting the distribution, amounts and proportions of pigments accounted for the greater variation of coloration in domesticated birds than in their wild relations. Eumelanin generally causes grey or black coloration, while pheomelanin results in a reddish-brown colour. Other shades of brown may be produced through different combinations and concentrations of the two colours. [25] As in other animals, white pigeons have little to no pigment.[ citation needed ] Darker birds may be better able to store trace metals in their feathers due to their higher concentrations of melanin, which may help mitigate the negative effects of the metals, the concentrations of which are typically higher in urban areas. [26] Pigeons, especially homing or carrier breeds, are well known for their ability to find their way home from long distances. Despite these demonstrated abilities, wild rock doves are sedentary and rarely leave their local areas. It is hypothesized that in their natural, arid habitat, they rely on this sense to navigate back home after foraging as deserts rarely possess navigational landmarks that may be used. [5]

A rock pigeon's lifespan ranges from 3–5 years in the wild to 15 years in captivity, though longer-lived specimens have been reported. [27] The main causes of mortality in the wild are predators and persecution by humans.[ citation needed ] Some sources state the species was first introduced to North America in 1606 at Port Royal, Nova Scotia. [20] Although other sources cite Plymouth and Jamestown settlements in the early 17th century as the first place for species introduction in North America. [28]

In Chandigarh, India, showing that the iridescence wraps around the whole neck Rock pigeon in Chandigarh.jpg
In Chandigarh, India, showing that the iridescence wraps around the whole neck

Vocalizations

The call is a soft, slightly wavering, coo. Ornithologist David Sibley describes the display call as a whoo, hoo-witoo-hoo, [17] whereas the Cornell Lab of Ornithology describes it as a Coo, roo-c'too-coo. Variations include an alarm call, a nest call, and noises made by juveniles. [29] Sibley describes the nest call as a repeated hu-hu-hurrr. [17] When displaying, songs are partly sexual, partly threatening. They are accompanied by an inflated throat, tail fanning, strutting, and bowing. The alarm call, given at sight of predators, is a grunt-like oorhh. [29]

Non-vocal sounds include a loud flapping noise at take-off, feet stomping, hisses, and beak snapping. Wings may also be clapped during flights, usually during display fights or after copulation. Juveniles particularly snap their bills, usually to respond to nest invasion. The foot stomping appears deliberate, though for what purpose is unclear. Foot stomping is done with a certain foot first, showing that rock doves have "footedness", similar to human handedness. [29]

Osmoregulation

Distribution and habitat

Ferals, Norfolk Rock pigeons on cliffs.jpg
Ferals, Norfolk

Before the Columbian Exchange, rock doves were restricted to a natural resident range in western and southern Europe, North Africa, and extending into South Asia. They were carried into the New World aboard European ships between 1603 and 1607. [29] [30] The species (including ferals) has a large range, with an estimated global extent of occurrence of 10,000,000 km2 (3,900,000 sq mi). It has a large global population, including an estimated 17 to 28 million individuals in Europe. [1] Fossil evidence suggests the rock dove originated in southern Asia, and skeletal remains, unearthed in Israel, confirm its existence there for at least 300,000 years. [4] However, this species has such a long history with humans that it is impossible to identify its original range exactly. [5]

Wild pigeons reside in rock formations and cliff faces, settling in crevices to nest. They nest communally, often forming large colonies of many hundreds of individuals. [31] Wild nesting sites include caves, canyons, and sea cliffs. They will even live in the Sahara so long as an area has rocks, water, and some plant matter. They prefer to avoid dense vegetation. [29]

Rock doves have a commensal relationship with humans, gaining both ample access to food and nesting spots in civilized areas. Human structures provide an excellent imitation of cliff structures, making rock doves very common around human habitation. Skyscrapers, highway overpasses, farm buildings, abandoned buildings, and other human structures with ample crevices are conducive to rock dove nesting. Thus the modern range of the rock dove is due in large part to humans. [29] Agricultural settlements are favoured over forested ones. [32] Ideal human nesting attributes combine areas with tall buildings, green spaces, ample access to human food, and schools. Conversely, suburban areas which are far from city centers and have high street density are the least conducive to pigeons. [33] Their versatility among human structures is evidenced by a population living inside a deep well in Tunisia. [29]

Feral pigeons are usually unable to find these accommodations, so they must nest on building ledges, walls or statues. They may damage these structures via their feces; starving birds can only excrete urates, which over time corrodes masonry and metal. In contrast, a well-fed bird passes mostly solid feces, containing only small amounts of uric acid.[ citation needed ]

Behaviour and ecology

Pigeons are often found in pairs in the breeding season, but are usually gregarious. [3]

Breeding

Two squabs, a few days old Young pigeon 1.jpg
Two squabs, a few days old
Incubating an egg, showing their relatively flimsy nests Pigeon incubating egg 1.jpg
Incubating an egg, showing their relatively flimsy nests
Courtship display

The rock dove breeds at any time of the year, but peak times are spring and summer. Nesting sites are along coastal cliff faces, as well as the artificial cliff faces created by apartment buildings with accessible ledges or roof spaces. [34] Pigeons can compete with native birds for nest sites. [35] For some avian species, such as seabirds, it could be a conservation issue. [36] Current evidence suggests that wild, domestic and feral pigeons mate for life, although their long-term bonds are not unbreakable. [37] They are socially monogamous, but extra-pair matings do occur, often initiated by males. [38] Due to their ability to produce crop milk, pigeons can breed at any time of year. Pigeons breed when the food supply is abundant enough to support embryonic egg development, which in cities, can be any time of the year. Laying of eggs can take place up to six times per year.[ citation needed ]

Pigeons are often found in pairs during the breeding season, but usually the pigeons are gregarious, living in flocks of 50 to 500 birds (dependent on the food supply). [39]

Courtship rituals can be observed in urban parks at any time of the year. The male on the ground or rooftops puffs up the feathers on his neck to appear larger and thereby impress or attract attention. He approaches the female at a rapid walking pace while emitting repetitive quiet notes, often bowing and turning as he comes closer. [40] At first, the female invariably walks or flies a short distance away and the male follows her until she stops. At this point, he continues the bowing motion and very often makes full- or half-pirouettes in front of the female. [41] The male then proceeds to feed the female by regurgitating food, as they do when feeding the young.[ citation needed ] The male then mounts the female, rearing backwards to be able to join their cloacae. The mating is very brief, with the male flapping his wings to maintain balance on top of the female. [40]

The nest is a flimsy platform of straw and sticks, laid on a ledge, under cover, often on the window ledges of buildings. [5] Two white eggs are laid; incubation, shared by both parents, lasts 17 to 19 days. [6] The newly hatched squab (nestling) has pale yellow down and a flesh-coloured bill with a dark band. For the first few days, the baby squabs are tended and fed (through regurgitation) exclusively on "crop milk" (also called "pigeon milk" or "pigeon's milk"). The pigeon milk is produced in the crops of both parents in all species of pigeon and dove. Pigeons are altricial and their fledging period is about 30 days. [19]

Feeding

A rock dove eating grains A pet pigeon eating rice grains.jpg
A rock dove eating grains

Rock doves are omnivorous, but prefer plant matter: chiefly fruits and grains. [42]

Studies of pigeons in a semi-rural part of Kansas found that their diet includes the following: 92% maize, 3.2% oats, 3.7% cherry, along with small amounts of knotweed, elm, poison ivy and barley. [43] Feral pigeons can be seen eating grass seeds and berries in parks and gardens in the spring, but plentiful sources exist throughout the year from scavenging (e.g., food remnants left inside of dropped fast food cartons, in the form of popcorn, cake, peanuts, bread and currants) [43] and they also eat insects and spiders. Additional food is also usually available from waste bins, tourists or residents who feed bird seed to pigeons for reasons such as empathy, fun, tradition and as a means for social interaction. [44] [45] Pigeons tend to congregate in large, often thick flocks when feeding on discarded food, and may be observed flying skillfully around trees, buildings, telephone poles and cables and even through moving traffic just to reach a food source.[ citation needed ]

Pigeons feed on the ground in flocks or individually. Pigeons are naturally granivorous, eating seeds that fit down their gullet. They may sometimes consume small invertebrates such as worms or insect larvae as a protein supplement. As they do not possess an enlarged cecum as in European wood pigeons, they cannot digest adult plant tissue; the various seeds they eat contain the appropriate nutrients they require. [46] [47] [48] While most birds take small sips and tilt their heads backwards when drinking, pigeons are able to dip their bills into the water and drink continuously, without having to tilt their heads back. In cities they typically resort to scavenging human garbage, as unprocessed grain may be impossible to find. Pigeon groups typically consist of producers, which locate and obtain food, and scroungers, which feed on food obtained by the producers. Generally, groups of pigeons contain a greater proportion of scroungers than producers. [49]

Preening

Pigeons primarily use powder down feathers for preening, which gives a soft and silky feel to their plumage. They have no preen gland or at times have very rudimentary preen glands, so oil is not used for preening. Rather, powder down feathers are spread across the body. These have a tendency to disintegrate, and the powder, akin to talcum powder, helps maintain the plumage. [50] Some varieties of domestic pigeon have modified feathers called "fat quills". These feathers contain yellow, oil-like fat that derives from the same cells as powder down. This is used while preening and helps reduce bacterial degradation of feathers by feather bacilli. [51]

Survival

Predators

With only their flying abilities protecting them from predation, rock pigeons are a favourite almost around the world for a wide range of raptors. In fact, with feral pigeons existing in almost every city in the world, they may form the majority of prey for several raptor species that live in urban areas. Peregrine falcons and Eurasian sparrowhawks are natural predators of pigeons and quite adept at catching and feeding upon this species. Up to 80% of the diet of peregrine falcons in several cities that have breeding falcons is composed of feral pigeons. [52] Some common predators of feral pigeons in North America are raccoons, opossums, red-tailed hawks, great horned owls, eastern screech owls, and accipiters. The birds that prey on pigeons in North America can range in size from American kestrels to golden eagles [53] and may even include crows, gulls and ravens.[ citation needed ] On the ground the adults, their young and their eggs are at risk from feral and domestic cats. [6] Doves and pigeons are considered to be game birds, since many species are hunted and used for food in many of the countries in which they are native. [54]

The body feathers have dense, fluffy bases and are loosely attached to the skin, hence they drop out easily. When a predator catches a pigeon large numbers of feathers come out in the attacker's mouth and the pigeon may use this temporary distraction to make an escape. [50] It also tends to drop the tail feathers when preyed upon or under traumatic conditions, probably as a distraction mechanism. [55]

Parasites

Tinaminyssus melloi female.jpg Fly June 2008-2.jpg
Tinaminyssus melloi, a nasal mite.Pigeon louse fly ( Pseudolynchia canariensis ), a blood-sucking ectoparasite.

Pigeons may harbour a diverse parasite fauna. [56] They often host the intestinal helminths Capillaria columbae and Ascaridia columbae. Their ectoparasites include the ischnoceran lice Columbicola columbae , Campanulotes bidentatus compar, the amblyceran lice Bonomiella columbae, Hohorstiella lata, Colpocephalum turbinatum, the mites Tinaminyssus melloi, Dermanyssus gallinae, Dermoglyphus columbae, Falculifer rostratus and Diplaegidia columbae. The hippoboscid fly Pseudolynchia canariensis is a typical blood-sucking ectoparasite of pigeons in tropical and subtropical regions.

Relationship to humans

Domestication

Domestic pigeons Pigeon Revivim 2.jpg
Domestic pigeons

Rock doves have been domesticated for several thousand years, giving rise to the domestic pigeon (Columba livia domestica). [6] They may have been domesticated as long as 5,000 years ago. [57] Numerous breeds of fancy pigeons of all sizes, colours, and types have been bred. [58] Domesticated pigeons are used as homing pigeons as well as food and pets. They were in the past also used as carrier pigeons.

War pigeons

So-called war pigeons have played significant roles during wartime, and many pigeons have received awards and medals for their services in saving hundreds of human lives.

Medical uses

Pigeons have notably been "employed" as medical imaging data sorters. They have been successfully trained under research conditions to examine data on a screen for the purposes of detecting breast cancer. They appear to use their innate visual navigation skills to do so. [59]

Feral pigeon

A feral in Nanjing, China Feralpigeon.jpg
A feral in Nanjing, China

Many domestic birds have got lost, escaped or been released over the years and have given rise to feral pigeons. These show a variety of plumages, although many have the blue-barred pattern as does the pure rock dove. Feral pigeons are found in cities and towns all over the world. [60] The scarcity of the pure wild species is partly due to interbreeding with feral birds. [22]

Human health

Contact with pigeon droppings poses a minor risk of contracting histoplasmosis, cryptococcosis and psittacosis, [61] and long-term exposure to both droppings and feathers can induce an allergy known as bird fancier's lung. Pigeons are not a major concern in the spread of West Nile virus: though they can contract it, they apparently do not transmit it. [62]

Some contagions are transmitted by pigeons; for example, the bacteria Chlamydophila psittaci is endemic among pigeons [63] and causes psittacosis in humans. It is generally transmitted from handling pigeons or their droppings (more commonly the latter). Psittacosis is a serious disease but rarely fatal (less than 1%). Pigeons are also important vectors for various species of the bacteria Salmonella , [64] [65] which causes diseases such as salmonellosis and paratyphoid fever.

Pigeons are also known to host avian mites, which can infest human habitation and bite humans, a condition known as gamasoidosis. [66] [67] However, infesting mammals is relatively rare. [68]

Avian influenza

Pigeons may, however, carry and spread avian influenza. One study has shown that adult pigeons are not clinically susceptible to the most dangerous strain of avian influenza, H5N1, and that they do not transmit the virus to poultry. [69] Other studies have presented evidence of clinical signs and neurological lesions resulting from infection but found that the pigeons did not transmit the disease to poultry reared in direct contact with them. [70] [71] Pigeons were found to be "resistant or minimally susceptible" to other strains of avian influenza, such as the H7N7. [72]

Research into whether pigeons play a part in spreading bird flu have shown pigeons do not carry the deadly H5N1 strain. [73] Three studies have been done since the late 1990s by the US Agriculture Department's Southeast Poultry Research Laboratory in Athens, Georgia, according to the center's director, David Swayne. The lab has been working on bird flu since the 1970s. In one experiment, researchers squirted into pigeons' mouths liquid drops that contained the highly pathogenic H5N1 virus from a Hong Kong sample. The birds received 100 to 1,000 times the concentration that wild birds would encounter in nature. "We couldn't infect the pigeons", Swayne said. "So that's good news." [74] [75]

Stages of lifecycle

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The laughing dove is a small pigeon that is a resident breeder in Africa, the Middle East, South Asia, and Western Australia where it has established itself in the wild after being released from Perth Zoo in 1898. This small long-tailed dove is found in dry scrub and semi-desert habitats where pairs can often be seen feeding on the ground. It is closely related to the spotted dove which is distinguished by a white and black chequered necklace. Other names include laughing turtle dove, palm dove and Senegal dove while in Asia the name little brown dove is often used.

<span class="mw-page-title-main">Influenza A virus subtype H5N1</span> Subtype of influenza A virus

Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus which can cause illness in humans and many other species. A bird-adapted strain of H5N1, called HPAI A(H5N1) for highly pathogenic avian influenza virus of type A of subtype H5N1, is the highly pathogenic causative agent of H5N1 flu, commonly known as avian influenza. It is enzootic in many bird populations, especially in Southeast Asia. One strain of HPAI A(H5N1) is spreading globally after first appearing in Asia. It is epizootic and panzootic, killing tens of millions of birds and spurring the culling of hundreds of millions of others to stem its spread. Many references to "bird flu" and H5N1 in the popular media refer to this strain.

<span class="mw-page-title-main">Pink pigeon</span> Species of bird

The pink pigeon is a species of pigeon in the family Columbidae endemic to Mauritius. The pink pigeon nearly became extinct in the 1970s and the 1990s and is still very rare. It is the only Mascarene pigeon that has not become extinct. It was on the brink of extinction in 1991 when only 10 individuals remained, but its numbers have increased due to the efforts of the Durrell Wildlife Conservation Trust since 1977. While the population remains at below 500 birds as of 2011, the IUCN downlisted the species from Critically endangered to Endangered on the IUCN Red List in 2000, and then downlisted it again to Vulnerable in 2018.

<span class="mw-page-title-main">Domestic pigeon</span> Small domesticated bird

The domestic pigeon is a pigeon subspecies that was derived from the rock dove or rock pigeon. The rock pigeon is the world's oldest domesticated bird. Mesopotamian cuneiform tablets mention the domestication of pigeons more than 5,000 years ago, as do Egyptian hieroglyphics. Research suggests that domestication of pigeons occurred as early as 10,000 years ago.

<span class="mw-page-title-main">Transmission and infection of H5N1</span> Spread of an influenza virus

Transmission and infection of H5N1 from infected avian sources to humans has been a concern since the first documented case of human infection in 1997, due to the global spread of H5N1 that constitutes a pandemic threat.

<span class="mw-page-title-main">Uropygial gland</span> Gland

The uropygial gland, informally known as the preen gland or the oil gland, is a bilobed sebaceous gland possessed by the majority of birds used to distribute the gland's oil through the plumage by means of preening. It is located dorsally at the base of the tail and is greatly variable in both shape and size. In some species, the opening of the gland has a small tuft of feathers to provide a wick for the preen oil. It is a holocrine gland enclosed in a connective tissue capsule made up of glandular acini that deposit their oil secretion into a common collector tube ending in a variable number of pores (openings), most typically two. Each lobe has a central cavity that collects the secretion from tubules arranged radially around the cavity. The gland secretion is conveyed to the surface via ducts that, in most species, open at the top of a papilla.

<i>Petrophassa</i> Genus of birds

Petrophassa, commonly known as the rock pigeons, is a small genus of doves in the family Columbidae native to Australia, and similar to bronzewing pigeons.

<span class="mw-page-title-main">Imperial pigeon</span> Genus of birds

Ducula is a genus of the pigeon family Columbidae, collectively known as imperial pigeons. They are large to very large pigeons with a heavy build and medium to long tails. They are arboreal, feed mainly on fruit and are closely related to the other genus of fruit-eating doves, Ptilinopus. Both genera display brightly coloured plumage, predominantly green, often with contrasting under-parts of purple, orange or red. Some Ducula have prominently swollen ceres. They have large gapes and swallow seeds whole, playing an important role in seed dispersal.

<i>Haemoproteus</i> Genus of single-celled organisms

Haemoproteus is a genus of alveolates that are parasitic in birds, reptiles, and amphibians. Its name is derived from Greek: haima 'blood' and Proteus, a sea god that had the power to assume various shapes. The name Haemoproteus was first used in the description of H. columbae in the blood of the pigeon Columba livia by Walther Kruse in 1890. This was also the first description of this genus. Two other genera—Halteridium and Simondia—are now considered to be synonyms of Haemoproteus.

<i>Pseudolynchia canariensis</i> Species of fly

Pseudolynchia canariensis, the pigeon louse fly or pigeon fly, is a species of biting fly in the family of louse flies, Hippoboscidae.

References

  1. 1 2 3 BirdLife International (2019) [amended version of 2016 assessment]. "Columba livia". IUCN Red List of Threatened Species . 2019: e.T22690066A155493121. doi: 10.2305/IUCN.UK.2016-3.RLTS.T22690066A155493121.en . Retrieved 19 February 2022.
  2. "Columba livia". Integrated Taxonomic Information System . Retrieved 2008-02-23.
  3. 1 2 3 4 5 6 7 Gibbs, David; Eustace Barnes; John Cox (2010-06-30). Pigeons and Doves: A Guide to the Pigeons and Doves of the World. United Kingdom: Pica Press. ISBN   978-1-873403-60-0.
  4. 1 2 Blechman, Andrew (2007). Pigeons-The fascinating saga of the world's most revered and reviled bird. St Lucia, Queensland: University of Queensland Press. ISBN   978-0-7022-3641-9.
  5. 1 2 3 4 5 "Rock Pigeon". All About Birds. Cornell Laboratory of Ornithology. Retrieved 2008-02-19.
  6. 1 2 3 4 5 6 Levi, Wendell (1977). The Pigeon. Sumter, S.C.: Levi Publishing Co, Inc. ISBN   0-85390-013-2.
  7. "Rock Pigeon Life History, All About Birds, Cornell Lab of Ornithology". www.allaboutbirds.org. Retrieved 2019-12-24.
  8. Gill, F., ed. (2020). IOC World Bird List v10.2 (Report). International Ornithological Committee. doi: 10.14344/ioc.ml.10.2 .
  9. Gmelin, Johann Friedrich (1789). Systema naturae per regna tria naturae : secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis (in Latin). Vol. 1, Part 2 (13th ed.). Lipsiae [Leipzig]: Georg. Emanuel. Beer.
  10. James A. Jobling. Helm Dictionary of Scientific Bird Names. Bloomsbury Publishing p. 114 ISBN   1408125013
  11. Liddell, Henry George & Robert Scott (1980). A Greek-English Lexicon (Abridged ed.). United Kingdom: Oxford University Press. ISBN   0-19-910207-4.
  12. Simpson, D.P. (1979). Cassell's Latin Dictionary (5th ed.). London: Cassell Ltd. p. 883. ISBN   0-304-52257-0.
  13. Jobling, J. (2010). Helm Dictionary of Scientific Bird Names (PDF). London: Christopher Helm. ISBN   978-1-408-12501-4. S2CID   82496461. Archived from the original (PDF) on August 15, 2019. Retrieved August 20, 2019.
  14. In J.F. Gmelin's edition of Linné's Systema Naturae appeared in Leipzig, 1788-93.
  15. Baptista, L. (2009). "Darwin's pigeons and the evolution of the columbiforms: recapitulation of ancient genes" (PDF). Acta Zoológica Mexicana. Nueva Serie. 25 (3): 719–741. doi:10.21829/azm.2009.253674.
  16. Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (January 2023). "Pigeons". IOC World Bird List Version 13.1. International Ornithologists' Union. Retrieved 10 June 2023.
  17. 1 2 3 Sibley, D. (2014). The Sibley Guide to Birds (2nd ed.). New York: Alfred A. Knopf. p. 201. ISBN   978-0-307-95790-0. OCLC   869807502.
  18. Gilbert, Thomas (2014). "Pigeons, Domestication of". In Smith, Claire (ed.). Encyclopedia of Global Archaeology. New York, NY: Springer New York. doi:10.1007/978-1-4419-0465-2. ISBN   978-1-4419-0426-3. S2CID   220616743.
  19. 1 2 Jahan, Shah. "Feral Pigeon". The Birds I Saw. Archived from the original on June 29, 2008. Retrieved 2008-02-19.
  20. 1 2 White, Helen. "Rock Pigeons". www.diamonddove.info. Helen White. Retrieved 2008-02-18.[ self-published source? ]
  21. 1 2 3 4 5 6 Jones, Marc. E. H.; Button, David J.; Barrett, P.M., Paul M; Porro B., Laura (2019). "Digital dissection of the head of the rock dove (Columba livia) using contrast-enhanced computed tomography". Zoological Letters. 5: 1–31. doi: 10.1186/s40851-019-0129-z . PMC   6558907 . PMID   31205748.
  22. 1 2 Wright, Mike. "Wildlife Profiles: Pigeon". Arkansas Urban Wildlife. Archived from the original on 2008-06-10. Retrieved 2008-02-18.
  23. Davis, J.Michael (1975). "Socially induced flight reactions in pigeons". Animal Behaviour. 23: 597–601. doi:10.1016/0003-3472(75)90136-0. S2CID   53171567.
  24. Haag-Wackernagel, Daniel; Heeb, Philipp; Leiss, Andreas (2006). "Phenotype-dependent selection of juvenile urban Feral Pigeons Columba livia". Bird Study. 53 (2): 169. Bibcode:2006BirdS..53..163H. doi: 10.1080/00063650609461429 . S2CID   84205070.
  25. Haase, E; Ito, S; Sell, A; Wakamatsu, K (1992). "Melanin Concentrations in Feathers from Wild and Domestic Pigeons". Journal of Heredity. 83: 64–67. doi:10.1093/oxfordjournals.jhered.a111160.
  26. Chatelain, Marion; Gasparini, Julien; Frantz, A (2015). "Do trace metals select for darker birds in urban areas? An experimental exposure to lead and zinc". Global Change Biology. 22 (7): 2380–91. doi:10.1111/gcb.13170. PMID   27282322. S2CID   27962528.
  27. "Columba livia (domest.)". BBC Science & Nature. Retrieved 2008-02-19.
  28. "Rock Dove Facts - NatureMapping". naturemappingfoundation.org. Retrieved 2021-06-30.
  29. 1 2 3 4 5 6 7 Lowther, Peter E.; Johnston, Richard F. (March 2020). Billerman, Shawn M (ed.). "Rock Pigeon (Columba livia)" . Birds of the World. Cornell Lab of Ornithology. doi:10.2173/bow.rocpig.01. S2CID   216428981.
  30. Schorger, A. W. (October 1952). "Introduction of the Domestic Pigeon". The Auk. 69 (4): 462–463. doi: 10.2307/4081033 . ISSN   0004-8038. JSTOR   4081033.
  31. Kaufman, Kenn (November 2014). "Guide to North American Birds: Rock Pigeon". Audubon. National Audubon society . Retrieved 2021-10-16.
  32. Hetmański, Tomasz; Bocheński, Marcin; Tryjanowski, Piotr; Skórka, Piotr (2011-06-01). "The effect of habitat and number of inhabitants on the population sizes of feral pigeons around towns in northern Poland". European Journal of Wildlife Research. 57 (3): 421–428. doi: 10.1007/s10344-010-0448-z . ISSN   1439-0574. S2CID   20351031.
  33. Przybylska, Katarzyna; Haidt, Andżelika; Myczko, Łukasz; Ekner-Grzyb, Anna; Rosin, Zuzanna M.; Kwieciński, Zbigniew; Tryjanowski, Piotr; Suchodolska, Joanna; Takacs, Viktoria; Jankowiak, Łukasz; Tobółka, Marcin (2012-06-30). "Local and landscape-level factors affecting the density and distribution of the Feral Pigeon Columba livia var. domestica in an urban environment". Acta Ornithologica. 47 (1): 37–45. doi:10.3161/000164512X653908. S2CID   56390450.
  34. "Columba livia". Australian Museum Online. Archived from the original on February 13, 2008. Retrieved 2008-02-18.
  35. Forero, M.G.; Tella, J.L.; Donázar, J.A.; Hiraldo, F. (1996-12-01). "Can interspecific competition and nest site availability explain the decrease of lesser kestrel Falco naumanni populations?". Biological Conservation. 78 (3): 289–293. Bibcode:1996BCons..78..289F. doi:10.1016/S0006-3207(96)00011-0. hdl: 10261/57592 . ISSN   0006-3207.
  36. Rodríguez, Beneharo; Rodríguez, Airam; Siverio, Felipe; Martínez, Juan Manuel; Sacramento, Enrique; Acosta, Yarci. "Feral pigeons as a nest competitor for a small seabird". Biological Invasions. doi: 10.1007/s10530-022-02746-1 . hdl: 10486/703009 . S2CID   247095691.
  37. Marchesan, M. (2002). "Operational sex ratio and breeding strategies in the Feral Pigeon Columba livia". Ardea. 90 (2): 249–57.
  38. Lovell-Mansbridge, C.; Birkhead, T.R. (1998). "Do female pigeons trade pair copulations for protection?". Animal Behaviour. 56 (1): 249–57. doi:10.1006/anbe.1998.0774. PMID   9710482. S2CID   901466.
  39. Gibbs, David; Barnes, Eustace; Cox, John (2001). Pigeons and Doves: A Guide to the Pigeons and Doves of the World. United Kingdom: Pica Press. p. 624. ISBN   978-1-873403-60-0.
  40. 1 2 Riddle, Gordon (Summer 1971). "The breeding season in a rural colony of Feral Pigeons" (PDF). The Journal of the Scottish Ornithologist's Club. 6: 323.
  41. Whitman, C. O. (1919). Posthumous Works: The behaviour of pigeons, ed. by Harvey A. Carr. Washington: Carnegie Institution of Washington. p. 10.
  42. Lowther, P.; Johnston, R. (2020). Billerman, S. (ed.). "Rock pigeon (Columba livia), version 1.0" . Birds of the World. Cornell Lab of Ornithology. doi:10.2173/bow.rocpig.01. S2CID   216428981 . Retrieved August 6, 2020.
  43. 1 2 Roof, Jennifer (2001-05-08). "ADW: Columba livia: INFORMATION". Animaldiversity.org. Retrieved 2022-08-05.
  44. Haag-Wackernagel, D. (1997). "Die soziokulturellen Ursachen des Taubenproblems". Deutsche Tierärztliche. 104: 52–57.
  45. Cabalceta, A.; Barrientos, Z. (2019). "Tradición: una nueva razón para alimentar las palomas urbanas (Columba livia; Columbiformes: Columbidae), y cómo controlarlas de manera sostenible". UNED Research Journal. 11 (3). doi: 10.22458/urj.v11i3.2216 .
  46. Murton, R.K.; Westwood, N.J. (1966). "The foods of the Rock Dove and Feral Pigeon". Bird Study. 13 (2): 130–146. Bibcode:1966BirdS..13..130M. doi:10.1080/00063656609476116.
  47. "Rock Pigeon". 13 November 2014.
  48. MARY H. CLENCH; JOHN R. MATHIAS (1995). "THE AVIAN CECUM: A REVIEW" (PDF). Wilson Bull. 107(l): 93–121. Retrieved 13 March 2022.
  49. Dugatkin, Lee Alan (2014). Principles of Animal Behavior (3rd ed.). New York: W. W. Norton Company. pp. 373–376. ISBN   9780393920451.
  50. 1 2 "Columbiformes (Pigeons, Doves, and Dodos)". Encyclopedia.com. Grzimek's Animal Life Encyclopedia COPYRIGHT 2004 The Gale Group Inc. Retrieved 26 April 2017.
  51. Peters, Anne; Klonczinski, Eva; Delhey, Kaspar (March 2010). "Fat quill secretion in pigeons: Could it function as a cosmetic?". Animal Biology. 60: 69–78. doi:10.1163/157075610X12610595764219.
  52. White, Clayton M.; Nancy J. Clum; Tom J. Cade & W. Grainger Hunt. "Peregrine Falcon". Birds of North America Online. Retrieved 2011-08-30.
  53. Roof, Jennifer (2001). "Columba livia common pigeon". Animal Diversity Web University of Michigan. Retrieved 2008-02-20.
  54. Butler, Krissy Anne. "Keeping & Breeding Doves & Pigeons". Game Bird Gazette Magazine. Archived from the original on 2008-02-28. Retrieved 2008-02-23.
  55. Naish, Darren. "The detachable tails of pigeons". Scienceblogs.com. 2006-2017 ScienceBlogs LLC. Retrieved 18 September 2008.
  56. Rózsa L (1990). "The ectoparasite fauna of feral pigeon populations in Hungary" (PDF). Parasitologia Hungarica. 23: 115–119.
  57. Johnston, Richard F. (1992-07-01). "Evolution in the Rock Dove: Skeletal Morphology". The Auk. 109 (3): 530–542. doi:10.1093/auk/109.3.530 (inactive 31 January 2024). ISSN   0004-8038.{{cite journal}}: CS1 maint: DOI inactive as of January 2024 (link)
  58. McClary, Douglas (1999). Pigeons for Everyone. Great Britain: Winckley Press. ISBN   0-907769-28-4.
  59. Levenson, Richard M.; Krupinski, Elizabeth A.; Navarro, Victor M.; Wasserman, Edward A. (2015). "Pigeons (Columba livia) as Trainable Observers of Pathology and Radiology Breast Cancer Images". PLOS ONE. 10 (11): e0141357. Bibcode:2015PLoSO..1041357L. doi: 10.1371/journal.pone.0141357 . PMC   4651348 . PMID   26581091.
  60. "Why study pigeons? To understand why there are so many colors of feral pigeons". Cornell Lab of Ornithology. Archived from the original on June 12, 2008. Retrieved 2008-02-20.
  61. "Facts about pigeon-related diseases". The New York City Department of Health and Mental Hygiene. Archived from the original on March 4, 2009. Retrieved 2009-03-05.
  62. Chalmers, Dr Gordon A. "West Nile Virus and Pigeons". Panorama lofts. Archived from the original on October 26, 2009. Retrieved 2008-02-18.{{cite web}}: CS1 maint: unfit URL (link)
  63. Geigenfeind, Ila; Vanrompay, Daisy; Haag-Wackernagel, Daniel (February 2012). "Prevalence of Chlamydia psittaci in the feral pigeon population of Basel, Switzerland". Journal of Medical Microbiology . 61 (Pt 2): 261–265. doi: 10.1099/jmm.0.034025-0 . PMID   21921110.
  64. Gargiulo, Antonio; Russo, Tamara Pasqualina; Schettini, Rita; Mallardo, Karina; et al. (April 2014). "Occurrence of enteropathogenic bacteria in urban pigeons (Columba livia) in Italy". Vector Borne and Zoonotic Diseases. 14 (4). Larchmont, New York: 251–255. doi:10.1089/vbz.2011.0943. PMID   24661012.
  65. Osman, Kamelia M.; Mehrez, Mona; Erfan, Ahmed M.; Al Atfeehy, Nayerah (May 2013). "Salmonella enterica isolated from pigeon (Columba livia) in Egypt". Foodborne Pathogens and Disease. 10 (5): 481–483. doi:10.1089/fpd.2012.1347. PMID   23531124.
  66. Regan, Anne Marie (1 December 1987). "Nosocomial Dermatitis and Pruritus Caused by Pigeon Mite Infestation". Archives of Internal Medicine. 147 (12): 2185–7. doi:10.1001/archinte.1987.00370120121021. ISSN   0003-9926. PMID   3689070.
  67. Pezzi, Marco; Leis, Marilena; Chicca, Milvia; Roy, Lise (1 October 2017). "Gamasoidosis caused by the special lineage L1 of Dermanyssus gallinae (Acarina: Dermanyssidae): A case of heavy infestation in a public place in Italy". Parasitology International. 66 (5): 666–670. doi:10.1016/j.parint.2017.05.001. ISSN   1383-5769. PMID   28483708.
  68. George, David R; Finn, Robert D; Graham, Kirsty M; Mul, Monique F; Maurer, Veronika; Moro, Claire Valiente; Sparagano, Olivier AE (25 March 2015). "Should the poultry red mite Dermanyssus gallinae be of wider concern for veterinary and medical science?" (PDF). Parasites & Vectors. 8 (178): 178. doi: 10.1186/s13071-015-0768-7 . PMC   4377040 . PMID   25884317 . Retrieved 10 February 2021.
  69. Liu Y, Zhou J, Yang H, et al. (2007). "Susceptibility and transmissibility of pigeons to Asian lineage highly pathogenic avian influenza virus subtype H5N1". Avian Pathol. 36 (6): 461–5. doi:10.1080/03079450701639335. PMID   17994324. S2CID   13181639.
  70. Klopfleisch R, Werner O, Mundt E, Harder T, Teifke JP (2006). "Neurotropism of highly pathogenic avian influenza virus A/chicken/Indonesia/2003 (H5N1) in experimentally infected pigeons (Columbia livia f. domestica)". Vet. Pathol. 43 (4): 463–70. doi: 10.1354/vp.43-4-463 . PMID   16846988.
  71. Werner O, Starick E, Teifke J, et al. (2007). "Minute excretion of highly pathogenic avian influenza virus A/chicken/Indonesia/2003 (H5N1) from experimentally infected domestic pigeons (Columbia livia) and lack of transmission to sentinel chickens". J. Gen. Virol. 88 (Pt 11): 3089–93. doi: 10.1099/vir.0.83105-0 . PMID   17947534.
  72. Panigrahy B, Senne DA, Pedersen JC, Shafer AL, Pearson JE (1996). "Susceptibility of pigeons to avian influenza". Avian Dis. 40 (3): 600–4. doi:10.2307/1592270. JSTOR   1592270. PMID   8883790.
  73. "Facts about pigeon-related diseases". The New York City Department of Health and Mental Hygiene. Archived from the original (Web article) on 13 January 2008. Retrieved 4 January 2008.
  74. Turner, Brad. "Avian flu virus H5N1 and pigeons: the facts". Purebred Pigeon. Retrieved 4 January 2008.
  75. Panigrahy, B.; Senne, D.A.; Pedersen, J.C.; Shafer, A.L.; Pearson, J.E. (1996). "Susceptibility of pigeons to avian influenza". Avian Dis. 40 (3): 600–04. doi:10.2307/1592270. JSTOR   1592270. PMID   8883790.