Rock dove

Appearance

The adult of the nominate subspecies of the rock dove is 29 to 37 cm long with a 62 to 72 cm wingspan. Weight for wild or feral rock doves ranges from 238–380 g, though overfed domestic and semi-domestic individuals can exceed normal weights. It has a dark bluish-gray 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, the tail is 9.5 to 11 cm, the bill is around 1.8 cm and the tarsus is 2.6 to 3.5 cm.

The adult female is almost identical to the male, but the iridescence on the neck is less intense and more restricted to the rear and sides, while that on the breast is often very obscure.

The white lower back of the pure rock dove is its best identification character; 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.

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 in colour and are encapsulated in a grey-white eye ring. The feet are red to pink.

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. Though fields are visited for grain and green food, it is often not plentiful enough as to be a viewed as pest.

Pigeons feed on the ground in flocks or individually. They roost together in buildings or on walls or statues. When drinking, most birds take small sips and tilt their heads backwards to swallow the water. Pigeons are able to dip their bills into the water and drink continuously without having to tilt their heads back. When disturbed, a pigeon in a group will take off with a noisy clapping sound.

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.The purpose of thermoregulation is to maintain body temperature by producing heat through physiological and metabolic reactions. Heat gain should equal to rates of heat loss. If the body temperature is unbalanced, the animal becomes either warmer or colder. Heat production in birds is associated to shivering. The large flight muscles- pectoralis as well as the leg muscles generate heat by shivering.

"Columba Livia" have strong wings with flexible feathers which provide enough insulation to keep their body warm and dry. The fat layers and feathers reduce the flow of heat between an animal and its environment and lower the energy cost of keeping warm. In some birds the heat loss from the legs and feet is limited in cold weather because of a countercurrent mechanism that saves heat and in hot weather it can serve as heat radiators which increase blood flow.

Thermoregulation in birds requires cooling as well as warming. At low temperature birds can tuck head and neck under their wings to reduce heat loss. The heat is lost by the pigeons as an insensible heat by evaporation of water from the respiratory system and skin when temperature gradient is less and relative humidity is low. At the relatively high temperature birds increase their respiration rate to increase their cooling by evaporation. The panting is important in birds which involves gular flutter. The pouch richly supplied with blood vessels in the floor of the mouth; the rapid movement of the upper throat tissues - fluttering the pouch increases evaporation. Pigeons can use evaporative cooling to keep body temperature close to 40 °C in air temperatures as high as 60 °C, as long as they have sufficient water.

Also from previous studies experiment shows that a bird is capable of evaporating enough water from the cloaca for thermoregulation and results suggests that some birds’ cloacal evaporation can be controlled and could serve as an important maneuver for thermoregulation at high ambient temperatures.

Naming

The rock dove was first described by Gmelin in 1789. The genus name "Columba" is the Latinized form of the Ancient Greek κόλυμβος, "a diver", from "κολυμβάω", "dive, plunge headlong, swim". Aristophanes and others use the word κολυμβίς, "diver", for the name of the bird, because of its swimming motion in the air. The specific epithet is derived from the Latin "livor", "bluish". Its closest relative in the "Columba" genus is the hill pigeon, followed by the other rock pigeons: the snow, speckled and white-collared pigeons.

The species is also known as the rock pigeon or blue rock dove, the former being the official name from 2004 to 2011, at which point the IOC changed their official listing to its original British name of rock dove. In common usage, this bird is still often simply referred to as the "pigeon". Pigeon chicks are called "squabs".There are 12 subspecies recognised by Gibbs; some of these may be derived from feral stock.
⤷  "C. l. livia", the nominate subspecies, occurs in western and southern Europe, northern Africa, and Asia to western Kazakhstan, the northern Caucasus, Georgia, Cyprus, Turkey, Iran, and Iraq.
⤷  "C. l. atlantis" of Madeira, the Azores and Cape Verde, is a very variable population with chequered upperparts obscuring the black wingbars, and is almost certainly derived from feral pigeons.
⤷  "C. l. canariensis" of the Canary Islands, is smaller and averages darker than the nominate subspecies.
⤷  "C. l. gymnocyclus" from Senegal and Guinea to Ghana, Benin and Nigeria is smaller and very much darker than nominate "C. l. livia". It is almost blackish on the head, rump and underparts with a white back and the iridescence of the nape extending onto the head.
⤷  "C. l. targia" breeds in the mountains of the Sahara east to Sudan. It is slightly smaller than the nominate form, with similar plumage, but the back is concolorous with the mantle instead of white.
⤷  "C. l. dakhlae" is confined to the two oases in central Egypt. It is smaller and much paler than the nominate subspecies.
⤷  "C. l. schimperi" is found in the Nile Delta south to northern Sudan. It closely resembles "C. l. targia", but has a distinctly paler mantle.
⤷  "C. l. palaestinae" occurs from Syria to Sinai and Arabia. It is slightly larger than "C. l. schimperi" and has darker plumage.
⤷  "C. l. gaddi", breeds from Azerbaijan and Iran east to Uzbekistan is larger and paler than "C. l. palaestinae" with which it intergrades in the west. It also intergrades with the next subspecies to the east.
⤷  "C. l. neglecta", is found in the mountains of eastern Central Asia. It is similar to the nominate subspecies in size, but is darker with a stronger and more extensive iridescent sheen on the neck. It intergrades with the next race in the south.
⤷  "C. l. intermedia" occurs in Sri Lanka and in India south of the Himalayan range of "C. l. neglecta". It is similar to that subspecies, but darker with a less contrasting back.
⤷  "C. l. nigricans" in Mongolia and north China is variable and probably derived from feral stock.

Distribution

The rock dove has a restricted natural resident range in western and southern Europe, North Africa, and into South Asia. The rock dove is often found in pairs in the breeding season but is usually gregarious. The species has a large range, with an estimated global extent of occurrence of 10,000,000 km2. It has a large global population, including an estimated 17–28 million individuals in Europe. Fossil evidence suggests the rock dove originated in southern Asia and skeletal remains unearthed in Israel confirm their existence there for at least three hundred thousand years. However, this species has such a long history with humans that it is impossible to tell exactly where the species' original range was. Its habitat is natural cliffs, usually on coasts. Its domesticated form, the feral pigeon, has been widely introduced elsewhere, and is common, especially in cities, over much of the world. A rock pigeon's lifespan is anywhere from 3–5 years in the wild to 15 years in captivity, though longer-lived specimens have been reported. The main causes of mortality in the wild are predators and persecution by humans. The species was first introduced to North America in 1606 at Port Royal, Nova Scotia.

Behavior

"Columba Livia" does a few things to regulate its body temperature. Normally it will drink water after they have eaten, but when stressed by heat they can drink whenever needed to lower its body temperature. Another way it can regulate its heat is through Ptilomotor responses. Ptilomotor responses allow for better insulation of the body, because smooth muscle contractions make the feathers stand up straighter, which traps more air next to the skin. "Columba Livia" exhibits Ta selecting behavior. It will seek out its desired thermal neutral zone temperatures, in order to expend less energy heating and cooling its body.

Habitat

The rock dove has a restricted natural resident range in western and southern Europe, North Africa, and into South Asia. The rock dove is often found in pairs in the breeding season but is usually gregarious. The species has a large range, with an estimated global extent of occurrence of 10,000,000 km2. It has a large global population, including an estimated 17–28 million individuals in Europe. Fossil evidence suggests the rock dove originated in southern Asia and skeletal remains unearthed in Israel confirm their existence there for at least three hundred thousand years. However, this species has such a long history with humans that it is impossible to tell exactly where the species' original range was. Its habitat is natural cliffs, usually on coasts. Its domesticated form, the feral pigeon, has been widely introduced elsewhere, and is common, especially in cities, over much of the world. A rock pigeon's lifespan is anywhere from 3–5 years in the wild to 15 years in captivity, though longer-lived specimens have been reported. The main causes of mortality in the wild are predators and persecution by humans. The species was first introduced to North America in 1606 at Port Royal, Nova Scotia.

Reproduction

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.

The nest is a flimsy platform of straw and sticks, laid on a ledge, under cover, often on the window ledges of buildings. Two white eggs are laid; incubation is shared by both parents lasting from seventeen to nineteen days. The newly hatched squab has pale yellow down and a flesh-coloured bill with a dark band. For the first few days, the baby squab is tended and fed exclusively on "crop milk". The pigeon milk is produced in the crops of "both" parents in all species of pigeons and doves. The fledging period is about 30 days.Gas exchange across eggshells results in water loss from the egg. However, the egg must retain enough water to hydrate the embryo. This results in the knowledge that changing temperatures and humidity can affect the eggshell's architecture. Behavioral adaptations in "Columba livia" and other birds, such as the incubation of their eggs, can help with the effects of these changing environments. It was found that eggshell architecture undergoes selection decoupled from behavioral effects, and that humidity may be a driving selective pressure.
Low humidity requires enough water to keep the embryo from desiccation, and high humidity needs enough water loss to facilitate the initiation of pulmonary respiration. The water loss from the eggshell is directly linked to the growth rate of the species. The ability of the embryo to tolerate extreme water loss is due to the parental behavior in species colonizing in different environments. Studies have been done showing that wild habitats of "Columba livia" and other birds have a higher rate tolerance of various humidity levels, but "Columba livia" do prefer areas where the humidity closely matched their native breeding conditions.
The pore areas of the shells allow water to diffuse in and out of the shell, preventing the possible harming of the embryo due to the high rates of water retention. If an eggshell is thinner, it can cause a decrease in pore length, and an increase in conductance and pore area. A thinner eggshell can also cause a decrease in mechanical restriction of the embryo.

Predators

With only its flying abilities protecting it from predation, rock pigeons are a favorite almost around the world for a wide range of raptorial birds. In fact, with feral pigeons existing in almost every city in the world, they may form the majority of prey for several raptor species who live in urban areas. Peregrine falcons and Eurasian sparrowhawks are natural predators of pigeons that are 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. Some common predators of feral pigeons in North America are opossums, raccoons, red-tailed hawks, great horned owls, eastern screech owls and "Accipiter"s. The birds that predate pigeons in North America can range in size from American kestrels to golden eagles and can even include gulls, crows, and ravens. On the ground the adults, their young and their eggs are at risk from feral and domestic cats. Doves and pigeons are considered to be game birds as many species have been hunted and used for food in many of the countries in which they are native.