Tropicbirds are a
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
, Phaethontidae, of tropical
pelagic
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...
seabird
Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same enviro ...
s. They are the sole living representatives of the order
Phaethontiformes
The Phaethontiformes are an order of birds. They contain one extant family, the tropicbirds (Phaethontidae), and one extinct family Prophaethontidae from the early Cenozoic. Several fossil genera have been described.
The tropicbirds were tradit ...
. For many years they were considered part of the
Pelecaniformes
The Pelecaniformes are an order of medium-sized and large waterbirds found worldwide. As traditionally—but erroneously—defined, they encompass all birds that have feet with all four toes webbed. Hence, they were formerly also known by such n ...
, but genetics indicates they are most closely related to the
Eurypygiformes
Eurypygiformes is an order formed by the kagus, comprising two species in the family Rhynochetidae endemic to New Caledonia, and the sunbittern (''Eurypyga helias'') from the tropical regions of the Americas. Its closest relatives appear to b ...
. There are three species in one
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
, ''Phaethon''. The scientific names are derived from
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
''phaethon'', "sun".
They have predominantly white
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, ...
with elongated tail feathers and small feeble legs and feet.
Taxonomy, systematics and evolution
The
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''Phaethon'' was introduced in 1758 by the Swedish naturalist
Carl Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
in 1758 in the
tenth edition of his ''
Systema Naturae
' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nomen ...
''. The name is from
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
''phaethōn'' meaning "sun". The
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
was designated as the
red-billed tropicbird
The red-billed tropicbird (''Phaethon aethereus'') is a tropicbird, one of three closely related species of seabird of tropical oceans. Superficially resembling a tern in appearance, it has mostly white plumage with some black markings on the wi ...
(''Phaethon aethereus'') by
George Robert Gray
George Robert Gray FRS (8 July 1808 – 6 May 1872) was an English zoologist and author, and head of the ornithological section of the British Museum, now the Natural History Museum, in London for forty-one years. He was the younger brother ...
in 1840.
Tropicbirds were traditionally grouped in the
order Pelecaniformes
The Pelecaniformes are an order of medium-sized and large waterbirds found worldwide. As traditionally—but erroneously—defined, they encompass all birds that have feet with all four toes webbed. Hence, they were formerly also known by such n ...
, which contained the
pelican
Pelicans (genus ''Pelecanus'') are a genus of large water birds that make up the family Pelecanidae. They are characterized by a long beak and a large throat pouch used for catching prey and draining water from the scooped-up contents before s ...
s,
cormorants and shags,
darters
The darters, anhingas, or snakebirds are mainly tropical waterbirds in the family Anhingidae, which contains a single genus, ''Anhinga''. There are four living species, three of which are very common and widespread while the fourth is rarer and ...
,
gannets and boobies and
frigatebirds
Frigatebirds are a family of seabirds called Fregatidae which are found across all tropical and subtropical oceans. The five extant species are classified in a single genus, ''Fregata''. All have predominantly black plumage, long, deeply forked ...
; in the
Sibley–Ahlquist taxonomy, the Pelecaniformes were united with other groups into a large "Ciconiiformes". More recently this grouping has been found to be massively
paraphyletic
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
(missing closer relatives of its distantly related groups) and split again.
Microscopic analysis of eggshell structure by Konstantin Mikhailov in 1995 found that the eggshells of tropicbirds lacked the covering of thick microglobular material of other Pelecaniformes. Jarvis, ''et al''.'s 2014 paper "Whole-genome analyses resolve early branches in the tree of life of modern birds" aligns the tropicbirds most closely with the
sunbittern
The sunbittern (''Eurypyga helias'') is a bittern-like bird of tropical regions of the Americas, and the sole member of the family Eurypygidae (sometimes spelled Eurypigidae) and genus ''Eurypyga''. It is found in Central and South America, and ...
and the
kagu
The kagu or cagou (''Rhynochetos jubatus'') is a crested, long-legged, and bluish-grey bird endemic to the dense mountain forests of New Caledonia. It is the only surviving member of the genus ''Rhynochetos'' and the family Rhynochetidae, alt ...
of the
Eurypygiformes
Eurypygiformes is an order formed by the kagus, comprising two species in the family Rhynochetidae endemic to New Caledonia, and the sunbittern (''Eurypyga helias'') from the tropical regions of the Americas. Its closest relatives appear to b ...
, with these two clades forming the sister group of the "core water birds", the
Aequornithes, and the Metaves hypothesis abandoned.
![Tropicbird Seychelles](https://upload.wikimedia.org/wikipedia/commons/5/5b/Tropicbird_Seychelles.jpg)
Order Phaethontiformes
* Family †Prophaethontidae
Harrison & Walker 1976
** Genus †''
Prophaethon
''Prophaethon'' is an extinct genus of seabird that lived during the Early Eocene (Ypresian, c.56-49 mya). It is essentially known from fairly comprehensive remains of a single individual, namely skull and some limb bones, which were recovered f ...
''
Andrews 1899
*** †''
Prophaethon shrubsolei''
Andrews 1899
** Genus †''
Lithoptila
''Lithoptila abdounensis'' is an extinct species of seabird that lived during the Late Paleocene (Thanetian) of Morocco. It is a distant relative of the tropicbird
Tropicbirds are a family, Phaethontidae, of tropical pelagic seabirds. They ar ...
''
Bourdon, Bouya & Iarochène 2005
*** †''
Lithoptila abdounensis''
Bourdon, Bouya & Iarochène 2005
* Family Phaethontidae
Brandt 1840
** Genus †''
Proplegadis''
Harrison & Walker 1971
*** †''
Proplegadis fisheri''
Harrison & Walker 1971
** Genus †''
Phaethusavis''
Bourdon, Amaghzaz & Bouya 2008
*** †''
Phaethusavis pelagicus''
Bourdon, Amaghzaz & Bouya 2008
** Genus †''
Heliadornis
''Heliadornis'' is a genus of prehistoric seabirds related to modern tropicbirds, but native to temperate climates. They lived in the Miocene. Two species have been recognized. ''Heliadornis ashbyi'' is known from remains in Maryland in the Unite ...
''
Olson 1985
*** †''
H. ashbyi''
Olson 1985
*** †''
H. minor''
Kessler 2009
*** †''
H. paratethydicus''
Mlíkovský 1997
** Genus ''Phaethon''
Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
, 1758
***
Red-billed tropicbird
The red-billed tropicbird (''Phaethon aethereus'') is a tropicbird, one of three closely related species of seabird of tropical oceans. Superficially resembling a tern in appearance, it has mostly white plumage with some black markings on the wi ...
''P. aethereus'' (tropical Atlantic, eastern Pacific, and Indian oceans)
***
Red-tailed tropicbird, ''P. rubricauda'' (Indian Ocean and the western and central tropical Pacific)
***
White-tailed tropicbird
The white-tailed tropicbird (''Phaethon lepturus'') is a tropicbird. It is the smallest of three closely related seabirds of the tropical oceans and smallest member of the order Phaethontiformes. It is found in the tropical Atlantic, western Paci ...
, ''P. lepturus'' (widespread in tropical waters, except in the eastern Pacific)
The red-billed tropicbird is basal within the genus. The split between the red-billed tropicbird and the other two tropicbirds is hypothesized to have taken place about six million years ago, with the split between the red-tailed and white-tailed tropicbird taking place about four million years ago.
''
Phaethusavis'' and ''
Heliadornis
''Heliadornis'' is a genus of prehistoric seabirds related to modern tropicbirds, but native to temperate climates. They lived in the Miocene. Two species have been recognized. ''Heliadornis ashbyi'' is known from remains in Maryland in the Unite ...
'' are prehistoric genera of tropicbirds described from
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 ...
s.
Extant species
Description
![Red tailed tropic bird](https://upload.wikimedia.org/wikipedia/commons/b/b7/Red_tailed_tropic_bird.jpg)
Tropicbirds range in size from 76 cm to 102 cm in length and 94 cm to 112 cm in wingspan. Their plumage is predominantly white, with elongated central tail feathers. The three species have different combinations of black markings on the face, back, and wings. Their bills are large, powerful and slightly decurved. Their heads are large and their necks are short and thick. They have totipalmate feet (that is, all four toes are connected by a web). The legs of a tropicbird are located far back on their body, making walking impossible, so that they can only move on land by pushing themselves forward with their feet.
[
The tropicbirds' call is typically a loud, piercing, shrill, but grating whistle, or crackle. These are often given in a rapid series when they are in a display flight at the colony. In old literature they were referred to as boatswain (bo'sun'/bosun) birds due their loud whistling calls.]
Behaviour and ecology
Tropicbirds frequently catch their prey by hovering and then plunge-diving, typically only into the surface-layer of the waters. They eat mostly fish, especially flying fish
The Exocoetidae are a family of marine fish in the order Beloniformes class Actinopterygii, known colloquially as flying fish or flying cod. About 64 species are grouped in seven to nine genera. While they cannot fly in the same way a bird d ...
, and occasionally squid. Tropicbirds tend to avoid multi-species feeding flocks, unlike the frigatebirds
Frigatebirds are a family of seabirds called Fregatidae which are found across all tropical and subtropical oceans. The five extant species are classified in a single genus, ''Fregata''. All have predominantly black plumage, long, deeply forked ...
, which have similar diets.
Tropicbirds are usually solitary or in pairs away from breeding colonies. There they engage in spectacular courtship displays. For several minutes, groups of 2–20 birds simultaneously and repeatedly fly around one another in large, vertical circles, while swinging the tail streamers from side to side. If the female likes the presentation, she will mate with the male in his prospective nest-site. Occasionally, disputes will occur between males trying to protect their mates and nesting areas.
Tropicbirds generally nest in holes or crevices on the bare ground. The female lays one white egg, spotted brown, and incubates for 40–46 days. The incubation is performed by both parents, but mostly the female, while the male brings food to feed the female. The chick hatches with grey down. It will stay alone in the nest while both parents search for food, and they will feed the chick twice every three days until fledging, about 12–13 weeks after hatching. The young are not able to fly initially; they will float on the ocean for several days to lose weight before flight.
Tropicbird chicks have slower growth than nearshore birds, and they tend to accumulate fat deposits while young. That, along with one-egg clutches, appears to be an adaptation to a pelagic lifestyle where food is often gathered in large amounts, but may be hard to find.
Notes
References
* (HTML abstract)
*Oiseaux.net (2006)
Red-billed Tropicbird
Retrieved 4-SEP-2006.
* (HTML abstract)
External links
by Don Roberson
by Brian Patteson
Tropicbird videos
on the Internet Bird Collection
{{Authority control
*
Seabirds
Extant Eocene first appearances