Domestic pigeon

Domestic pigeon
The domestic pigeon (Columba livia domestica or Columba livia forma domestica) is a pigeon subspecies that was derived from the rock dove (also called the 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.
Pigeons have held historical importance to humans as food, pets, holy animals, and messengers. Due to their homing ability, pigeons have been used to deliver messages, including during the world wars. Despite this, city pigeons today are seen as pests, mainly due to their droppings. Feral pigeons are considered invasive in many parts of the world, though they have a positive impact on wild bird populations, serving as an important prey species for birds of prey.
History of domestication
The earliest recorded mention of pigeons comes from Mesopotamia some 5,000 years ago. Pigeon Valley in Cappadocia has rock formations that were carved into dovecotes.
Despite the long history of pigeons, little is known about the specifics of their initial domestication. Which subspecies of C. livia was the progenitor of domestics, exactly when, how many times, where and how they were domesticated, and how they spread, remains unknown. Their fragile bones and similarity to wild birds make the fossil record a poor tool for their study. Thus most of what is known comes from written accounts, which almost certainly do not cover the first stages of domestication. There is strong evidence that some divergences in appearance between the wild-type rock dove and domestic pigeons, such as checkered wing patterns and red/brown coloration, may be due to introgression by cross-breeding with the speckled pigeon.
Ancient Egyptians kept vast quantities of them, and would sacrifice tens of thousands at a time for ritual purposes. Akbar the Great traveled with a coterie of thousands of pigeons.
The domestic pigeon was brought to America by European colonists as an easy source of food and as messengers. Around the 18th century, European interest in fancy pigeons began, and breeders there greatly expanded the variety of pigeons, importing birds from the Middle East and South Asia and mixing different breeds to create new ones.
Because domestic and feral pigeons have extensively interbred with wild rock doves, wild-type pigeons may not truly exist anymore, or are nearly extinct. This frequent admixture further muddies the true origins of pigeons.
Genetics
From a genetic perspective, there are two loose ancestral clades of pigeons, but there is striking genetic homogeneity due to frequent interbreeding and human directed cross-breeding; pigeon fanciers often do not enforce breed standards, unlike dogs. The first ancestral clade contains pigeons with exaggerated crops, tails, and manes; the second contains tumblers (the most diverse group), homing pigeons, owl pigeons, and those with exaggerated wattles.
Crest
A recessive allele in the EphB2 gene controls the crested-feather mutation in domestic pigeons. Pigeons with two copies of the crest allele grow neck and head feathers that point towards the top of the head, unlike other feathers that point towards the tail. Additionally, bacterial growth analysis suggests that crested pigeons have reduced bacterial-killing abilities due to reduced kinase activity. Pigeons may express the crest gene differently depending on its genetic heritage; two squabs from the same brood descending from the same pair may have one bird develop a peak crest, and the other a wild-type smooth head.
Foot feathering
Pigeons with feathers growing on their hind feet have differently expressed genes: a hindlimb-development gene called Pitx1 is less active than normal, and a forelimb-development gene called Tbx5 that normally develops the wings is also active in the feet, causing both feather growth and larger leg bones. The cause of these changes is a change in the regulatory sequences of DNA that control the expression of the Pitx1 and the Tbx5 genes, rather than mutations in the genes themselves. Pigeon foot feathering has been speculated to use similar pathways as extinct microraptorian dinosaurs, although in pigeons the foot feathering does not form an airfoil.
Hybridization
They can be crossed with the ringneck dove (Streptopelia risoria) to create offspring, but the offspring are not fertile.
Reproduction
Domestic pigeons reproduce exactly as wild rock pigeons do; settling in a safe, cool nook, building a flimsy stick nest, and laying two eggs that are incubated for a little longer than two weeks. Some breeds are so overbred that they may require human intervention to produce squabs successfully. A pigeon keeper may select breeding partners, but in an open loft the birds choose their own mate. Crop milk or pigeon milk produced by both male and female parent birds may occasionally be replaced with artificial substitutes. Both sexes of pigeons are extremely protective of their eggs and young, and often defend them vigorously from nest predators, including their human keepers.
Baby pigeons are squabs, squeakers, or peeps, the latter two being a reference to their cry when begging for food. Initially, the squabs are fed with crop milk (or when human-raised, an appropriate substitute). As they grow and become more mobile and alert, their parents transition them to their adult food of seeds and grains, and after fledging the chicks will follow their parents to the communal feeding ground; areas with plentiful forage that a pigeon flock uses. Here the chicks gain their independence and integrate into pigeon society.
Domestic pigeons were selected to breed faster than their wild ancestors; a lack of a breeding season, abundance of food in a domestic setting, and swift maturity (Squabs fledge in about a month, and often have already bred and fledged a few clutches of their own before reaching a year in age) leads to swift population growth of pigeons in the flock. This fact, and the number of lost pigeons in a race and releases, leads to exponential growth in free-living, feral populations.
Uses
For food
Pigeons bred for meat are generally called squab and harvested from young birds. Pigeons grow to a very large size in the nest before they are fledged and able to fly; during this stage of development they are often fattier and seen as being tastier than the fully-flighted adults. Squabs during this stage are valued as food; in neolithic and early agricultural communities they were an easy and reliable source of protein, the birds requiring only reliable sources of grains and water (which they independently foraged for) to enter breeding condition, and the rock formations they nested in would've made for attractive dwellings for early humans.
Pigeon meat, both from squabs and from adult birds, are still a source of protein for people worldwide. Breeds of pigeons harvested for their meat during adulthood are collectively known as utility pigeons. For commercial meat production a breed of large white pigeon, the King pigeon, has been developed by selective breeding.
Homing pigeons
Trained domestic pigeons are able to return to the home loft if released at a location that they have never visited before and that may be up to away. This ability a pigeon has to return home from a foreign location necessitates two sorts of information. The first, called "map sense" is their geographic location. The second, "compass sense" is the bearing they need to fly from their new location in order to reach their home. Both of these senses, however, respond to a number of different cues in different situations. The most popular conception of how pigeons are able to do this is that they are able to sense the Earth's magnetic field with tiny magnetic tissues in their head (magnetoception). Another theory is that pigeons have compass sense, which uses the position of the sun, along with an internal clock, to work out direction. However, studies have shown that if magnetic disruption or clock changes disrupt these senses, the pigeon can still manage to get home. The variability in the effects of manipulations to these sense of the pigeons indicates that there is more than one cue on which navigation is based and that map sense appears to rely on a comparison of available cues
Other potential cues used include:
The use of a sun compass
Nocturnal navigation by stars
Visual landmark map
Navigation by infrasound map
Polarised light compass
Olfactory stimuli (see also olfactory navigation)
Homing pigeons are a specialized type of pigeon bred for navigation and speed. Originally developed through selective breeding to carry messages, members of this variety of pigeon are still being used in the sport of pigeon racing and the ceremony of releasing white doves at social events.
Flying/Sporting
Pigeons are also kept by enthusiasts for the enjoyment of Flying/Sporting competitions. Unlike racers, these birds aren't released far from their home lofts; breeds such as tipplers are bred for the ability to hover above the loft for hours at a time. Their ability to hover for a long time shows the ability of the keeper to select for endurance.
Wild Pigeons naturally somersault when evading aerial predators such as large falcons; they are naturally selected by the extreme speeds that stooping falcons reach (over 320 km/h (200 mph)), being able to dodge this attack at the last second. Tumbler and roller pigeons are bred to enhance this ability; some birds have been recorded to be able to somersault from a standstill, and some breeds are even deliberately bred to a point where the rolling ability is debilitative, being wholly unable to fly due to it.
Exhibition breeds
Pigeon fanciers developed many exotic forms of pigeon through selective breeding. These are generally classed as fancy pigeons. Fanciers compete against each other at exhibitions or shows and the different forms or breeds are judged to a standard to decide who has the best bird. Among those breeds are the English carrier pigeons, a variety of pigeon with wattles and a unique, almost vertical, stance (pictures). There are many ornamental breeds of pigeons, including the "Duchess" breed, which has as a prominent characteristic feet that are completely covered by a sort of fan of feathers. The fantail pigeons are also very ornamental with their fan-shaped tail feathers.
Pigeon shows are conventions where pigeon fanciers and breeders meet to compete and trade their birds. The various pigeon breeds dubbed "American show" were developed specifically by pigeon show frequenters pursuing a certain show standard determined by the National Pigeon Association.
Experimentation
Domestic pigeons are model organisms; commonly used in laboratory experiments in biology, to test medicines, and in cognitive science.
Cognitive science
Pigeons have been trained to distinguish between cubist and impressionist paintings. In Project Sea Hunt, a US coast guard search and rescue project in the 1970s/1980s, pigeons were shown to be more effective than humans in spotting shipwreck victims at sea. Research in pigeons is widespread, encompassing shape and texture perception, exemplar and prototype memory, category-based and associative concepts, and many more unlisted here (see pigeon intelligence).
Pigeons are able to acquire orthographic processing skills, which form part of the ability to read, and basic numerical skills equivalent to those shown in primates.
Illegal predator killing by enthusiasts
In the United States, some pigeon keepers illegally trap and kill hawks and falcons to protect their pigeons. It is legal in some places though. In American pigeon-related organizations, some enthusiasts have openly shared their experiences of killing hawks and falcons, although this is frowned upon by some fanciers. Some of the major clubs condone this practice. It is estimated that almost 1,000 birds of prey have been killed in Oregon and Washington, and that 1,000–2,000 are killed in southern California annually. In June 2007, three Oregon men were indicted with misdemeanour violations of the Migratory Bird Treaty Act for killing birds of prey. Seven Californians and a Texan were also charged in the case.
In the West Midlands region of the United Kingdom pigeon fanciers have been blamed for a trap campaign to kill peregrine falcons. Eight illegal spring-loaded traps were found close to peregrine nests and at least one of the birds died. The steel traps are thought to have been set as part of a "concerted campaign" to kill as many of the birds as possible in the West Midlands.
Pigeon related illness
Pigeon breeders sometimes suffer from an ailment known as bird fancier's lung or pigeon lung. A form of hypersensitivity pneumonitis, pigeon lung is caused by the inhalation of the avian proteins found in feathers and dung. It can sometimes be combated by wearing a filtered mask.
Other pigeon related pathogens causing lung disease are Chlamydophila psittaci (which causes psittacosis), Histoplasma capsulatum (which causes histoplasmosis) and Cryptococcus neoformans, which causes cryptococcosis.
Feral pigeons
Many domestic birds have escaped or been released over the years, and have given rise to the feral pigeon. As a result of natural variation, feral pigeons demonstrate a wide variety of plumages, ranging from closely resembling wild rock doves, to patterns directly inherited from their domestic ancestors, though over time a population tends to homogenize and adopt a plumage that suits their environment, such as camouflaging against black asphalt. The scarcity of the pure wild species is partly due to interbreeding with feral birds. Domestic pigeons can often be distinguished from feral pigeons because they usually have a metal or plastic band around one (sometimes both) legs which shows, by a number on it, that they are registered to an owner.
Feral pigeons bear striking genetic resemblance to homing pigeons, supporting the idea that most feral pigeons trace their origins to homing pigeons who did not find their way home, or were otherwise sired by homing pigeons. The huge numbers of birds released in pigeon races and loft owners breaking down their lofts and leaving the pigeons to fend for themselves may be a significant factor in the persistence of urban pigeons.
See also
Doves as symbols
List of pigeon breeds
References
External links
National Pigeon Association (USA)
National Pigeon Association (Great Britain)
The Canadian Pigeon Fanciers Association
Domestic Pigeons Explained (Pigeonpedia)
https://pigeoncarecenter.blogspot.com/?m=1
Columba (genus)
Domesticated birds
Subspecies
Taxa named by Johann Friedrich Gmelin