Trocaz Pigeon
Encyclopedia
The Trocaz Pigeon, Madeira Laurel Pigeon or Long-toed Pigeon (Columba trocaz) is a pigeon which is endemic to the island of Madeira
Madeira
Madeira is a Portuguese archipelago that lies between and , just under 400 km north of Tenerife, Canary Islands, in the north Atlantic Ocean and an outermost region of the European Union...

. 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. 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
Laurisilva
Laurisilva or laurissilva is a subtropical forest, found in areas with high humidity and relatively stable and mild temperatures. They are characterised by evergreen, glossy-leaved tree species that look alike with leaves of lauroide type...

 forests, the Trocaz pigeon lays one white egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 in a flimsy twig nest. Its numbers fell sharply after human colonisation of the Madeira archipelago
Archipelago
An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...

, and it vanished altogether from Porto Santo Island
Porto Santo Island
Porto Santo Island is a Portuguese island northeast of Madeira Island in the North Atlantic Ocean; it is the northernmost and easternmost island of the archipelago of Madeira, located in the Atlantic Ocean west of Europe and Africa.- History :...

. The major cause of its population decline was habitat loss
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...

 from forest clearance, but hunting and nest predation by introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

 rats were also contributory factors. Protection of the laurel
Lauraceae
The Lauraceae or Laurel family comprises a group of flowering plants included in the order Laurales. The family contains about 55 genera and over 3500, perhaps as many as 4000, species world-wide, mostly from warm or tropical regions, especially Southeast Asia and South America...

 forests and a ban on hunting have enabled numbers to increase, although this species is still endangered.

Description

The Trocaz Pigeon is a rather plain, dark grey bird 40–45 cm (16–18 in) long with a 68–74 cm (27–29 in) 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 feather
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...

s 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
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

, with limited or no development of the silvery neck patch. Its closed wings have a scaly appearance due to pale buff 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: uh-uh hrooh-hrooh ho-ho. 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
Madeiran Wood Pigeon
The Madeiran Wood Pigeon was an endemic subspecies of the Wood Pigeon for Madeira . This Wood Pigeon is endemic to the Laurel forest habitat....

. This was paler than the Trocaz Pigeon and had white wing patches and a more extensive green iridescence
Iridescence
Iridescence is generally known as the property of certain surfaces which appear to change color as the angle of view or the angle of illumination changes...

 on the nape
Nape
The nape is the back of the neck. In technical anatomical/medical terminology, the nape is referred to by the word nucha, which also gives the adjective corresponding to "nape" in English, "nuchal"....

, but it became extinct before 1924. Bolle's Pigeon
Bolle's Pigeon
The Bolle's Pigeon is a species of Columba genus of the family Columbidae, of doves and pigeons, which is endemic to the Canary Islands, Spain. This bird is named after the German naturalist Carl Bolle, who was the first to distinguish it from the Laurel 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
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...

, so there is no range overlap. The only other pigeon currently present on Madeira is the Feral Pigeon
Feral Pigeon
Feral pigeons , also called city doves, flying rats, city pigeons or street pigeons, are derived from domestic pigeons that have returned to the wild. The domestic pigeon was originally bred from the wild Rock Pigeon, which naturally inhabits sea-cliffs and mountains. All three types readily...

; 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
Columba (genus)
The large bird genus Columba comprises a group of medium to large stout-bodied pigeons, often referred to as the typical pigeons. The terms "dove" and "pigeon" are used indiscriminately for smaller and larger Columbidae, respectively...

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
Afep Pigeon
The Afep Pigeon also known as the African Wood-Pigeon, or Gray Wood-Pigeon is a member of the Columbidae family which lives in Africa.Like many other pigeons, it mainly feeds on grain and seeds....

. The two Macaronesia
Macaronesia
Macaronesia is a modern collective name for several groups of islands in the North Atlantic Ocean near Europe and North Africa belonging to three countries: Portugal, Spain, and Cape Verde...

n endemic pigeons, Bolle's and Trocaz, are thought to be derived from isolated island populations of C. palumbus.

The Atlantic archipelagos of the Canaries, Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...

, and Madeira have a volcanic origin and they have never been part of a continent. The formation of Madeira started in the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 and the island was substantially complete by 700,000 years ago. 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
Mitochondrion
In cell biology, a mitochondrion is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5 to 1.0 micrometers in diameter...

 and nuclear
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...

 DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 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
Laurel Pigeon
The Laurel Pigeon, White-tailed Laurel Pigeon, Paloma rabiche, is a species of bird in the Columba genus in the Columbidae family. It is a member of the family Columbidae of doves and pigeons, which is endemic to the Canary Islands, Spain...

, 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
Karl Heineken
Karl Heineken , also known as Carlos Heineken, was a German medical doctor and ornithologist. He lived on Madeira, a Portuguese island in Macaronesia, from 1826 until his death. He described the Trocaz Pigeon, a Madeiran endemic bird species...

, 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 species, although in the past Bolle's Pigeon was sometimes regarded as a subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 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
Porto Santo Island
Porto Santo Island is a Portuguese island northeast of Madeira Island in the North Atlantic Ocean; it is the northernmost and easternmost island of the archipelago of Madeira, located in the Atlantic Ocean west of Europe and Africa.- History :...

. 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
Laurisilva
Laurisilva or laurissilva is a subtropical forest, found in areas with high humidity and relatively stable and mild temperatures. They are characterised by evergreen, glossy-leaved tree species that look alike with leaves of lauroide type...

 forest or dense tree heaths which are cloud-covered for much of the year. The forests consist mainly of Azores Laurel
Laurus azorica
Laurus azorica is a species of plant in the Lauraceae family, related to laurus nobilis. It is a member of the genus Laurus and is commonly known as Azores Laurel. Laurus is a genus of evergreen trees belonging to the Laurel family, Lauraceae...

, Oreodaphne foetens, Til
Ocotea foetens
Ocotea foetens is a species of tree up to 40 m tall in the Lauraceae family. It is a common constituent in the laurisilva forests of the archipelagoes of Macaronesia: Madeira and Azores , and Canaries . It is commonly called "Til", "Tilo", "Stinkwood", Garoé, Oreodaphne foetens or Rain tree of...

, Madeira Mahogany
Persea indica
Persea indica is a species of plant in the Lauraceae family.It is found in the Azores, Madeira, and Canary Islands in Macaronesia. It is threatened by habitat loss.-Overview:...

, Canary Laurel
Appolonias barbujana
Apollonias barbujana , the Canary Laurel or Barbusano, is perhaps the only species of flowering plants belonging to Apollonias genus, in the laurel family, Lauraceae....

, Faya
Myrica faya
Myrica faya is a species of Myrica, native to Macaronesia , and possibly also southern Portugal....

, Lily of the Valley Tree
Clethra arborea
Clethra arborea, commonly known as the Lily of the Valley Tree, is a flowering plant in the genus Clethra. It is found in Macaronesia where it is native to Madeira, extinct in the Canary Islands, and considered an introduced species in the Azores...

 and the Picconia
Picconia excelsa
Picconia excelsa is a species of Picconia, endemic to Macaronesia, occurring on the Canary Islands and Madeira .-Description:...

. The Trocaz Pigeon prefers primary forests, but secondary growth
Secondary growth
In many vascular plants, secondary growth is the result of the activity of the two lateral meristems, the cork cambium and vascular cambium. Arising from lateral meristems, secondary growth increases the girth of the plant root or stem, rather than its length. As long as the lateral meristems...

 is used for feeding, and agricultural land is also visited, especially at times of fruit shortage. Most of the pigeons are found below 1000 m (3300 ft), 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.

Breeding

Pigeons can breed from their first year, and nesting occurs throughout the year, although mainly from February to June. The displays
Display (zoology)
Display is a form of animal behaviour, linked to survival of the species in various ways. One example of display used by some species can be found in the form of courtship, with the male usually having a striking feature that is distinguished by colour, shape or size, used to attract a female...

 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, 3.0–5.0 cm (1.2–2.0 in) 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, and the fruits and leaves of Small-leaved Holly
Ilex canariensis
Ilex canariensis ,is an endemic species of holly native to Macaronesian islands. It is a species of plant in the Aquifoliaceae family. It is found in Macaronesian islands of Madeira and Canarias ....

 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. 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
Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...

 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 160 km2 (60 mi2) of suitable habitat. The losses on the two islands, the only inhabited ones in the archipelago, were largely due to deforestation for wood and to create agricultural and grazing land.

The exclusion of livestock from the native forest allows it to regenerate and create more suitable habitat. Some illegal hunting and poisoning continues because of the damage this pigeon can do to crops, and the government allowed a cull
Culling
Culling is the process of removing animals from a group based on specific criteria. This is done either to reinforce certain desirable characteristics or to remove certain undesirable characteristics from the group...

 in 2004. Perhaps the main limiting factor on the rate at which the pigeon increases its numbers is eggs and young being taken by introduced Black Rats
Black Rat
The black rat is a common long-tailed rodent of the genus Rattus in the subfamily Murinae . The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe by the 1st century and spreading with Europeans across the world.-Taxonomy:The black rat was...

. The Parque Natural da Madeira
Parque Natural da Madeira
The Madeira Natural Park is a large biological reserve in Madeira with a unique endemic flora and fauna. It was created in 1982 to safeguard the natural heritage of the archipelago, and contains a number of endangered species including global rarities such as Zino's Petrel...

 national park
National park
A national park is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individual nations designate their own national parks differently A national park is a reserve of natural, semi-natural, or developed land that a sovereign state declares or...

 has a management plan for the Trocaz Pigeon, and it is hoped that an education campaign and the promotion of bird scarer
Bird scarer
A bird scarer is any one of a number devices designed to scare birds, usually employed by farmers to dissuade birds from eating recently planted arable crops....

s may reduce persecution. Its increasing population means that it is now classed as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...

 on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

, an improvement on its Threatened
Threatened species
Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...

 status in 1988. This species is protected under the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...

 Birds Directive
Birds Directive
The Birds Directive is a European Union directive adopted in 2009. It replaces Council Directive 79/409/EEC of 2 April 1979 on the conservation of wild birds which was modified several times and had become very unclear...

, and the laurel forests under the Habitats Directive.

External links

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