Trocaz pigeon
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The trocaz pigeon, Madeira laurel pigeon or long-toed pigeon (''Columba trocaz'') is a
pigeon Columbidae () is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with short necks and short slender bills that in some species feature fleshy ceres. They primarily ...
which is
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
to the island of Madeira,
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
. It is a mainly grey bird with a pinkish breast; its silvery neck patch and lack of white wing markings distinguish it from its close relative and probable ancestor, the
common wood pigeon The common wood pigeon or common woodpigeon (''Columba palumbus''), also known as simply wood pigeon, wood-pigeon or woodpigeon, is a large species in the dove and pigeon family (Columbidae), native to the western Palearctic. It belongs to the g ...
. Its call is a characteristic six-note cooing, weaker and lower-pitched than that of the wood pigeon. Despite its bulky, long-tailed appearance, this pigeon has a fast, direct flight. A scarce resident breeder in
laurisilva Laurel forest, also called laurisilva or laurissilva, is a type of Subtropics, subtropical forest found in areas with high humidity and relatively stable, mild temperatures. The forest is characterized by broadleaf tree species with evergreen, glo ...
forests, the trocaz pigeon lays one white egg in a flimsy twig nest. Its numbers fell sharply after human colonisation of the Madeira
archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Arc ...
, and it vanished altogether from Porto Santo Island. The major cause of its population decline was
habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
from forest clearance, but hunting and nest predation by introduced rats were also contributory factors. Protection of the
laurel Laurel may refer to: Plants * Lauraceae, the laurel family * Laurel (plant), including a list of trees and plants known as laurel People * Laurel (given name), people with the given name * Laurel (surname), people with the surname * Laurel (mus ...
forests and a ban on hunting have enabled numbers to increase, so that the species is no longer endangered.


Description

The trocaz pigeon is a rather plain, dark grey bird long with a wingspan. The upper back has a violet sheen, becoming green on the back of the neck, and the neck sides are patterned with silver-white. The tail is blackish with a wide, pale grey band, and the flight feathers are mainly black. The upper breast is pinkish, the eye is yellow, the bill has a yellow tip and a reddish-purple base, and the legs are red. The sexes are similar in appearance, but the juvenile has generally browner plumage, with limited or no development of the silvery neck patch. Its closed wings have a scaly appearance due to pale
buff Buff or BUFF may refer to: People * Buff (surname), a list of people * Buff (nickname), a list of people * Johnny Buff, ring name of American world champion boxer John Lisky (1888–1955) * Buff Bagwell, a ring name of American professional ...
feather edges. The trocaz pigeon's voice is weaker and deeper than that of common wood pigeon, typically consisting of six syllables with the middle pair of notes extended and stressed: '.Mullarney (1999) p. 216. When flying, it appears heavy and large-tailed, although its flight is rapid and direct. The common wood pigeon had a poorly defined Madeiran subspecies, '' Columba palumbus maderensis''. This was paler than the trocaz pigeon and had white wing patches and a more extensive green iridescence on the
nape The nape is the back of the neck. In technical anatomical/medical terminology, the nape is also called the nucha (from the Medieval Latin rendering of the Arabic , "spinal marrow"). The corresponding adjective is ''nuchal'', as in the term ''nu ...
, but it became extinct before 1924. Bolle's pigeon is more similar in appearance to the trocaz pigeon, although it lacks the whitish neck patch and has a more extensively pink breast. However, that species is endemic to the Canary Islands, so there is no range overlap. The only other pigeon currently present on Madeira is the
feral pigeon Feral pigeons (''Columba livia domestica'' or ''Columba livia forma urbana''), also called city doves, city pigeons, or street pigeons,Nagy, Kelsi, and Johnson, Phillip David. ''Trash animals: how we live with natures filthy, feral, invasive, an ...
; this is slimmer, has more pointed wings and a much smaller tail. It often has dark wing markings, and a lighter flight.


Taxonomy

The genus '' Columba'' is the largest within the pigeon family, and has the widest distribution. Its members are typically pale grey or brown, often with white head or neck markings or iridescent green or purple patches on the neck and breast. The neck feathers may be stiffened and aligned to form grooves. One of several subgroups within ''Columba'' consists of the widespread Eurasian common wood pigeon, Bolle's pigeon, the trocaz pigeon, and the African Afep pigeon. The two
Macaronesia Macaronesia (Portuguese: ''Macaronésia,'' Spanish: ''Macaronesia'') is a collection of four volcanic archipelagos in the North Atlantic, off the coasts of Africa and Europe. Each archipelago is made up of a number of Atlantic oceanic islands ...
n endemic pigeons, Bolle's and trocaz, are thought to be derived from isolated island populations of ''C. palumbus''.Gibbs (2000) p. 175. The Atlantic archipelagos of the Canaries,
Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...
, and Madeira have a volcanic origin and they have never been part of a continent. The formation of Madeira started in the
Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
and the island was substantially complete by 700,000 years ago. Retrieved 20 July 2010 At various times in the past, the major islands of these archipelagos were all colonised by ancestral wood pigeons, which evolved on their respective islands in isolation from the mainland populations. Mitochondrial and nuclear DNA sequences suggest that the ancestor of Bolle's pigeon may have arrived in the Canaries about 5  mya, but an older lineage that gave rise to another Canarian endemic, the laurel pigeon, ''C. junoniae'', may date from 20 mya. The most recent wood pigeon arrival on Madeira was that which gave rise to the subspecies ''C. palumbus maderensis''. The trocaz pigeon was formally described in 1829 by Karl Heineken, a German medical doctor and ornithologist who was living on Madeira at the time. He recognised it as different from the now-extinct local form of the common wood pigeon, which he called the "Palumbus", and noted that the two pigeons never interbred or habitually associated together. He suggested designating the new species by its local name, "trocaz". ''Trocaz'' is a variant of Portuguese ''torcaz'', the common wood pigeon; both words are ultimately derived from the Latin ''torquis'', a collar, and refer to the bird's coloured neck patches. This is a
monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...
species, although in the past Bolle's pigeon was sometimes regarded as a subspecies of the trocaz pigeon.


Distribution and habitat

The trocaz pigeon is endemic to the mountainous subtropical Atlantic main island of Madeira, although it formerly also bred on the neighbouring Porto Santo Island. It mainly occurs on the northern slopes of the mountains, but smaller numbers are found in the south where suitable patches of laurel forest remain. The natural habitat is tall
laurisilva Laurel forest, also called laurisilva or laurissilva, is a type of Subtropics, subtropical forest found in areas with high humidity and relatively stable, mild temperatures. The forest is characterized by broadleaf tree species with evergreen, glo ...
forest or dense tree heaths which are cloud-covered for much of the year.Snow (1998) p. 848. The forests consist mainly of
laurel Laurel may refer to: Plants * Lauraceae, the laurel family * Laurel (plant), including a list of trees and plants known as laurel People * Laurel (given name), people with the given name * Laurel (surname), people with the surname * Laurel (mus ...
, ''
Ocotea foetens ''Ocotea foetens'', commonly called til or stinkwood is a species of tree in the family Lauraceae. It is evergreen and grows up to 40 m tall. It is a common constituent of the laurisilva forests of Madeira and the Canary Islands. Leaf fossils of ...
'', Madeira mahogany, Canary laurel, faya, lily-of-the-valley-tree and '' Picconia excelsa''. The trocaz pigeon prefers primary forests, but
secondary growth In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips of ...
is used for feeding, and agricultural land is also visited, especially at times of fruit shortage. Most of the pigeons are found below , and their prime environment appears to be steep ravine-indented slopes along artificial watercourses, with the occasional large dead laurel tree and much tree heath. This species is highly mobile between different areas at different times of year.


Behaviour


Breeding

Pigeons can breed from their first year, and nesting occurs throughout the year, although mainly from February to June. The
displays A display device is an output device for presentation of information in visual or tactile form (the latter used for example in tactile electronic displays for blind people). When the input information that is supplied has an electrical signal the ...
are similar to those of the common wood pigeon; the male climbs quickly in flight, gives a loud wing-clap, and then glides down with his wings and tail spread. The display may be repeated two or three times before the bird returns to a perch. On the ground the male performs a bowing display with his neck inflated to show off the iridescent neck patches; meanwhile, the tail is raised, fanned, then closed again. This display is usually accompanied by calling. The nest is a typical pigeon construction, a flimsy structure of twigs and grasses usually placed high in a tree in thick forest. One, rarely two, smooth white eggs are laid, although no nest with two chicks has ever been found. The eggs, in size, are incubated for 19–20 days; the young are able to fly in 28 days, and are independent within eight weeks.


Feeding

The trocaz pigeon is exclusively herbivorous. Nearly 60% of its diet is fruit, with most of the rest being leaves, and just 1% is flowers. The fruits of Til, Azores Laurel and ''
Persea indica ''Persea indica'' is a large, evergreen tree in the laurel family (Lauraceae), native to humid uplands on Madeira and the Canary Islands in the North Atlantic. It belongs to the genus ''Persea'', a group of evergreen trees including the avocado. ...
'', and the fruits and leaves of small-leaved holly are the most frequently detected food items. Most seeds pass through the digestive system intact, apart from those of Azores Laurel, which are usually damaged. Fruit is the main component of the diet when it is readily available in autumn and winter, and leaves are consumed in spring and summer when fruits are scarce. In one study, 27% of the leaves consumed came from native trees, especially Small-leaved Holly, 61% from herbs and shrubs, and nearly 10% from introduced trees, mainly apples and peaches. This pigeon will feed in agricultural areas, where cabbage is the most commonly taken crop plant. Pigeon faeces from agricultural areas contain few native plants, and samples from forests have few crop species, so some individual birds may concentrate on crops. Feeding in cultivated land is commonest in winter, when fruit is readily available, so it appears not to be a shortage of natural foods that causes them to leave the forest, but is mostly opportunistic, resulting from the birds' movements through nearby forest. However, when the fruit crop of Til and Azores Laurel is poor, large numbers of pigeons may leave the forest to feed on cabbage, flowering cherries and vine shoots.Gibbs (2000) pp. 188–189. Competition for food with rats can be significant in parts of the island.


Status

The trocaz pigeon formerly bred on both the main island of Madeira and nearby Porto Santo Island. It was very abundant when the islands were first colonised by humans, but was
extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...
on Porto Santo, and by 1986 had declined to about 2,700 birds. Hunting was banned in that year, and there are now between 7,500 and 10,000 individuals in approximately of suitable habitat. The losses on the two islands, the only inhabited ones in the archipelago, were largely the result of
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
for
wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...
and to create agricultural and grazing land. The exclusion of livestock from the native forest allows the forest to regenerate and create more suitable habitat. Some
illegal hunting Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights. Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set a ...
and poisoning continues because of the damage this pigeon can do to crops, and the government allowed a
cull In biology, culling is the process of segregating organisms from a group according to desired or undesired characteristics. In animal breeding, it is the process of removing or segregating animals from a breeding stock based on a specific tr ...
in 2004. Perhaps the main limiting factor on the rate at which the pigeon increases its numbers is
predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
by introduced black rats on its eggs and young. The Madeira Nature Park has a management plan for the trocaz pigeon, and it is hoped that an education campaign and the promotion of
bird scarer Bird scarers is a blanket term used to describe devices designed for deterring birds by startling, confusing or otherwise repeling them, typically employed in commercial settings by farmers to dissuade birds from consuming and defecating on recen ...
s may reduce persecution. Its increasing population means that it is now classed as
Least Concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...
on the
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
, an improvement on its
Threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensa ...
status in 1988. This species is protected under the
European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...
Birds Directive The Birds Directive (formally known as Council Directive 2009/147/EC on the conservation of wild birds) is the oldest piece of EU legislation on the environment and one of its cornerstones which was unanimously adopted in April 1979 as the Dire ...
, and the laurel forests under the
Habitats Directive The Habitats Directive (more formally known as Council Directive 92/43/EEC on the Conservation of natural habitats and of wild fauna and flora) is a directive adopted by the European Community in 1992 as a response to the Berne Convention. The E ...
.


References


Cited text

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External links

* Madeira Birds
Trocaz Pigeon
{{Taxonbar, from=Q770308 Birds described in 1829 Birds of Madeira Endemic fauna of Madeira Columba (genus) Taxa named by Karl Heineken