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The trogons and
quetzal Quetzals () are strikingly colored birds in the trogon family. They are found in forests, especially in humid highlands, with the five species from the genus ''Pharomachrus'' being exclusively Neotropical, while a single species, the eared q ...
s are
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s in the
order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...
Trogoniformes which contains only one family, the Trogonidae. The family Trogonidae contains 46 species in seven
genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
. The
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
record of the trogons dates back 49 million years to the Early
Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...
. They might constitute a member of the basal radiation of the order
Coraciiformes The Coraciiformes are a group of usually colourful birds including the kingfishers, the bee-eaters, the rollers, the motmots, and the todies. They generally have syndactyly, with three forward-pointing toes (and toes 3 & 4 fused at their bas ...
and order
Passeriformes A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...
or be closely related to mousebirds and owls. The word ''trogon'' is Greek for "nibbling" and refers to the fact that these birds gnaw holes in trees to make their nests. Trogons are residents of
tropical forest Tropical forests (a.k.a. jungle) are forested landscapes in tropical regions: ''i.e.'' land areas approximately bounded by the tropic of Cancer and Capricorn, but possibly affected by other factors such as prevailing winds. Some tropical fore ...
s worldwide. The greatest diversity is in the Neotropics, where four genera, containing 24 species, occur. The genus ''
Apaloderma ''Apaloderma'' is a genus of birds in the family Trogonidae. The name is a compound word composed of two Greek words: ''hapalos'', meaning "delicate"and ''derma'', meaning "skin". Established by William John Swainson William John Swainson ...
'' contains the three
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
n
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
. The genera ''
Harpactes ''Harpactes'' is a genus of birds in the family Trogonidae found in forests in South and Southeast Asia, extending into southernmost China. They are strongly sexually dimorphic, with females generally being duller than males. Their back is brow ...
'' and ''
Apalharpactes ''Apalharpactes'' is a genus of birds in the family Trogonidae. They are restricted to humid highland forest on the Indonesian islands of Java and Sumatra. Unlike all other Asian trogons, their plumage is mainly green above and yellow below. Com ...
'', containing twelve species, are found in southeast Asia. They feed on
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...
s and
fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...
, and their broad bills and weak legs reflect their diet and arboreal habits. Although their flight is fast, they are reluctant to fly any distance. Trogons are generally not migratory, although some species undertake partial local movements. Trogons have soft, often colourful, feathers with distinctive male and female plumage. They are the only type of animal with a
heterodactyl In biology, dactyly is the arrangement of digits ( fingers and toes) on the hands, feet, or sometimes wings of a tetrapod animal. It comes from the Greek word δακτυλος (''dáktylos'') = "finger". Sometimes the ending "-dactylia" is u ...
toe arrangement. They nest in holes dug into trees or termite nests, laying 2–4 white or pastel-coloured eggs.


Evolution and taxonomy

The position of the trogons within the class Aves has been a long-standing mystery.Collar, N.J. (2001). "Family Trogonidae (Trogons)", pp. 80–129 in del Hoyo, J.; Elliot, A. & Sargatal, J. (eds.). (2001) ''Handbook of the Birds of the World, Vol. 6 Mousebirds to Hornbills''. Lynx Edicions, Barcelona, Spain. A variety of relations have been suggested, including the parrots, cuckoos, toucans, jacamars and puffbirds, rollers, owls and nightjars. More recent morphological and molecular evidence has suggested a relationship with the Coliiformes. The unique arrangement of the toes on the foot (see morphology and flight) has led many to consider the trogons to have no close relatives; to place them in their own order, possibly with the similarly atypical mousebirds as their closest relatives. The earliest formally described fossil specimen is a cranium from the Fur Formation Lower Eocene in Denmark (54 mya). Other trogoniform fossils have been found in the Messel pit deposits from the mid-
Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...
in Germany (49 mya), and in Oligocene and Miocene deposits from Switzerland and France respectively. The oldest New World fossil of a trogon is from the comparatively recent
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
(less than 2.588 mya). The family had been thought to have an Old World origin notwithstanding the current richness of the family, which is more diverse in the Neotropical New World. DNA evidence seemed to support an African origin for the trogons, with the African genus ''
Apaloderma ''Apaloderma'' is a genus of birds in the family Trogonidae. The name is a compound word composed of two Greek words: ''hapalos'', meaning "delicate"and ''derma'', meaning "skin". Established by William John Swainson William John Swainson ...
'' seemingly basal in the family, and the other two lineages, the Asian and American, breaking off between 20–36 million years ago. More recent studies show that the DNA evidence gives contradictory results concerning the basal phylogenetic relationships; so it is currently unknown if all extant trogons are descended from an African or an American ancestor or neither. The trogons are split into three subfamilies, each reflecting one of these splits, Aplodermatinae is the African subfamily and contains a single genus, ''Apaloderma.'' Harpactinae is the Asian subfamily and contains two genera, ''Harpactes'' and ''Apalharpactes''. ''Apalharpactes'', consisting of two species in Java and Sumatra, has only recently been accepted as a separate genus from ''Harpactes''. The remaining subfamily, the Neotropical Trogoninae, contains the remaining four genera, ''Trogon, Priotelus, Pharomachrus'' and ''Euptilotis''. The two Caribbean species of ''Priotelus'' were formerly different ones (''Temnotrogon'' on Hispaniola), and are extremely ancient. The two quetzal genera, ''Pharomachrus'' and ''Euptilotis'' are possibly derived from the final and most numerous genus of trogons in the Neotropics, ''Trogon''. A 2008 study of the genetics of ''Trogon'' suggested the genus originated in Central America and radiated into South America after the formation of the
Isthmus of Panama The Isthmus of Panama ( es, Istmo de Panamá), also historically known as the Isthmus of Darien (), is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country ...
(as part of the
Great American Interchange The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which lan ...
), thus making trogons relatively recent arrivals in South America.


Distribution and habitat

The majority of trogons are birds of tropical and subtropical forests. They have a cosmopolitan distribution in the worlds wet tropics, being found in the Americas, Africa and Asia. A few species are distributed into the temperate zone, with one species, the elegant trogon, reaching the south of the United States, specifically southern Arizona and the surrounding area. The Narina trogon of Africa is slightly exceptional in that it utilises a wider range of habitats than any other trogon, ranging from dense forest to fairly open savannah, and from the Equator to southern
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...
. It is the most widespread and successful of all the trogons. The eared quetzal of Mexico is also able to use more xeric habitats, but preferentially inhabits forests. Most other species are more restricted in their habitat, with several species being restricted to undisturbed primary forest. Within forests they tend to be found in the mid-story, occasionally in the canopy. Some species, particularly the quetzals, are adapted to cooler montane forest. There are a number of insular species; these include a number of species found in the Greater Sundas, one species in the
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
as well as two species
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
Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribb ...
and
Hispaniola Hispaniola (, also ; es, La Española; Latin and french: Hispaniola; ht, Ispayola; tnq, Ayiti or Quisqueya) is an island in the Caribbean that is part of the Greater Antilles. Hispaniola is the most populous island in the West Indies, and th ...
respectively. Outside of South East Asia and the Caribbean, however, trogons are generally absent from islands, especially oceanic ones. Trogons are generally sedentary, with no species known to undertake long migrations. A small number of species are known to make smaller migratory movements, particularly montane species which move to lower altitudes during different seasons. This has been demonstrated using radio tracking in the resplendent quetzal in
Costa Rica Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the no ...
and evidence has been accumulated for a number of other species. The Narina trogon of Africa is thought to undertake some localised short-distance migrations over parts of its range, for example birds of Zimbabwe's plateau savannah depart after the breeding season. A complete picture of these movements is however lacking. Trogons are difficult to study as their thick tarsi (feet bones) make
ringing Ringing may mean: Vibrations * Ringing (signal), unwanted oscillation of a signal, leading to ringing artifacts * Vibration of a harmonic oscillator ** Bell ringing * Ringing (telephony), the sound of a telephone bell * Ringing (medicine), a ring ...
studies difficult.


Morphology and flight

The trogons as a family are fairly uniform in appearance, having compact bodies and long tails (very long in the case of the quetzals), and short necks. Trogons range in size from the ,
scarlet-rumped trogon The scarlet-rumped trogon (''Harpactes duvaucelii'') is a species of bird in the family Trogonidae. It is found in Brunei, Indonesia, Malaysia, Myanmar, and Thailand. Its natural habitats are subtropical or tropical moist lowland forest, ...
to the , resplendent quetzal (not including the male quetzal's tail streamers). Their legs and feet are weak and short, and trogons are essentially unable to walk beyond a very occasional shuffle along a branch. They are even incapable of turning around on a branch without using their wings. The ratio of leg muscle to body weight in trogons is only 3%, the lowest known ratio of any bird. The arrangement of toes on the feet of trogons is also unique among birds, although essentially resembling the zygodactyl's two forward two backward arrangement of parrots and other near-passerines, the actual toes are arranged with usually inner hallux being the outer hind toe, an arrangement that is referred to as heterodactylous. The strong bill is short and the gape wide, particularly in the fruit eating quetzals, with a slight hook at the end. There is also a notch at the end of the bill and many species have slight serrations in the mandibles. The skin is exceptionally tender, making preparation of study skins difficult for museum curators. The skeletons of trogons are surprisingly slender, particularly the skulls which are very thin. The
plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...
of many species is iridescent, although not in most of the Asian species. The African trogons are generally green on the back with red bellies. The New World trogons similarly have green or deep blue upperparts but are more varied in their lowerparts. The Asian species tend towards red underparts and brown backs. The wings are short but strong, with the wing muscle ratio being around 22% of the body weight. In spite of the strength of their flight, trogons do not fly often or for great distances, generally flying no more than a few hundred metres at a time. Only the montane species tend to make long-distance flights. Shorter flights tend to be direct and swift, but longer flights are slightly undulating. Their flight can be surprisingly silent (for observers), although that of a few species is reportedly quite noisy.


Calls

The
calls Call or Calls may refer to: Arts, entertainment, and media Games * Call, a type of betting in poker * Call, in the game of contract bridge, a bid, pass, double, or redouble in the bidding stage Music and dance * Call (band), from Lahore, Pak ...
of trogons are generally loud and uncomplex, consisting of monosyllabic hoots and whistles delivered in varying patterns and sequences. The calls of the quetzals and the two Caribbean genera are the most complex. Among the Asian genera the
Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
n trogon (''Apalharpactes'') has the most atypical call of any trogon, research has not yet established whether the closely related Javan trogon has a similar call. The calls of the other Asian genus, ''Harpactes'', are remarkably uniform. In addition to the territorial and breeding calls given by males and females during the breeding seasons, trogons have been recorded as having aggression calls given by competing males and alarm calls.


Behaviour

Trogons are generally inactive outside of infrequent feeding flights. Among birdwatchers and biologists it has been noted that " art from their great beauty
hey Hey or Hey! may refer to: Music * Hey (band), a Polish rock band Albums * ''Hey'' (Andreas Bourani album) or the title song (see below), 2014 * ''Hey!'' (Julio Iglesias album) or the title song, 1980 * ''Hey!'' (Jullie album) or the title ...
are notorious ... for their lack of other immediately engaging qualities". Their lack of activity is possibly a defence against predation; trogons on all continents have been reported to shift about on branches to always keep their less brightly coloured backs turned towards observers, while their heads, which like owls can turn through 180 degrees, keep a watch on the watcher. Trogons have reportedly been preyed upon by hawks and predatory mammals; one report was of a resplendent quetzal taken while brooding young by a
margay The margay (''Leopardus wiedii'') is a small wild cat native to Central and South America. A solitary and nocturnal cat, it lives mainly in primary evergreen and deciduous forest. Until the 1990s, margays were hunted illegally for the wild ...
.


Diet and feeding

Trogons feed principally on insects, other arthropods, and fruit; to a lesser extent some small vertebrates such as lizards are taken. Among the insect prey taken one of the more important types are caterpillars; along with cuckoos, trogons are one of the few birds groups to regularly prey upon them. Some caterpillars are known to be poisonous to trogons though, like ''
Arsenura armida ''Arsenura armida'', the giant silk moth, is a moth of the family Saturniidae. It is found mainly in South and Central America, from Mexico to Bolivia, and Ecuador to south-eastern Brazil. It was first described by Pieter Cramer in 1779. It is ...
. ''The extent to which each food type is taken varies depending on geography and species. The three African trogons are exclusively insectivorous, whereas the Asian and American genera consume varying amounts of fruit. Diet is somewhat correlated with size, with larger species feeding more on fruit and smaller species focusing on insects. Prey is almost always obtained on the wing. The most commonly employed foraging technique is a sally-glean flight, where a trogon flies from an observation perch to a target on another branch or in foliage. Once there the birds hovers or stalls and snatches the item before returning to its perch to consume the item. This type of foraging is commonly used by some types of bird to obtain insect prey; in trogons and quetzals it is also used to pluck fruit from trees. Insect prey may also be taken on the wing, with the trogon pursuing flying insects in a similar manner to drongos and Old World flycatchers. Frogs, lizards and large insects on the ground may also be pounced on from the air. More rarely some trogons may shuffle along a branch to obtain insects, insect eggs and very occasionally nestling birds. Violaceous trogons will consume wasps and wasp larvae encountered while digging nests.


Breeding

Trogons are
territorial A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or an ...
and
monogamous Monogamy ( ) is a form of dyadic relationship in which an individual has only one partner during their lifetime. Alternately, only one partner at any one time ( serial monogamy) — as compared to the various forms of non-monogamy (e.g., pol ...
. Males will respond quickly to playbacks of their calls and will repel other members of the same species and even other hole-nesting species from around their nesting sites. Males attract females by singing, and, in the case of the resplendent quetzal, undertaking display flights. Some species have been observed in small flocks of 3–12 individuals prior to and sometimes during the breeding season, calling and chasing each other, but the function of these flocks is unclear. Trogons are cavity nesters. Nests are dug into rotting wood or termite nests, with one species, the violaceous trogon, nesting in
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...
nests. Nest cavities can either be deep upward slanting tubes that lead to fully enclosed chambers, or much shallower open niches (from which the bird is visible). Nests are dug with the beak, incidentally giving the family its name. Nest digging may be undertaken by the male alone or by both sexes. In the case of nests dug into tree trunks, the wood must be strong enough not to collapse but soft enough to dig out. Trogons have been observed landing on dead tree trunks and slapping the wood with their tails, presumably to test the firmness. The nests of trogons are thought to usually be unlined. Between two and four eggs are laid in a nesting attempt. These are round and generally glossy white or lightly coloured (buff, grey, blue or green), although they get increasingly dirty during incubation. Both parents incubate the eggs (except in the case of the
bare-cheeked trogon The bare-cheeked trogon (''Apaloderma aequatoriale'') is a species of bird in the family Trogonidae found in the rainforests of central Africa. Description The bare-cheeked trogon has bare yellow skin below its eyes and between its eyes and ...
, where apparently the male takes no part), with the male taking one long incubation stint a day and the female incubating the rest of the time. Incubation seems to begin after the last egg is laid. The incubation period varies by species, usually lasting between 16–19 days. On hatching the chicks are altricial, blind and naked. The chicks acquire feathers rapidly in some of the montane species, in the case of the mountain trogon in a week, but more slowly in lowland species like the black-headed trogon, which may take twice as long. The nestling period varies by species and size, with smaller species generally taking 16 to 17 days to
fledge Fledging is the stage in a flying animal's life between hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnera ...
, whereas larger species may take as long as 30 days, although 23–25 days is more typical.


Relationship with humans

Trogons and quetzals are considered to be "among the most beautiful of birds", yet they are also often reclusive and seldom seen. Little is known about much of their biology, and much of what is known about them comes from the research of neotropical species by the
ornithologist Ornithology is a branch of zoology that concerns the "methodological study and consequent knowledge of birds with all that relates to them." Several aspects of ornithology differ from related disciplines, due partly to the high visibility and th ...
Alexander Skutch Alexander Frank Skutch (May 20, 1904 – May 12, 2004) was a naturalist and writer. He published numerous scientific papers and books about birds and several books on philosophy. He is best remembered ornithologically for his pioneering work o ...
. Trogons are nevertheless popular birds with birdwatchers, and there is a modest
ecotourism Ecotourism is a form of tourism involving responsible travel (using sustainable transport) to natural areas, conserving the environment, and improving the well-being of the local people. Its purpose may be to educate the traveler, to provide fund ...
industry in particular to view quetzals in Central America.


Species list

* Order Trogoniformes ** Family Trogonidae


See also

* List of Trogoniformes by population


References


External links


Trogon videos
on the Internet Bird Collection
Tree of Life: Trogonidae
{{Taxonbar, from=Q191469 Extant Ypresian first appearances Taxa named by René Lesson