Falconiformes
Encyclopedia
The order
Falconiformes is a group of about 290 species
of bird
s that comprises the diurnal birds of prey
. Raptor
classification is difficult and the order is treated in several ways.
in this single order. However, in Europe
, it has become common to split the order into two: the falcon
s and caracara
s remain in the order Falconiformes (about 60 species in 4 groups), and the remaining 220-odd species (including the Accipitridae
eagle
s, hawk
s, and many others) are put in the separate order Accipitriformes
. The idea that Falconiformes should be divided into smaller orders comes from the suggestion that the order may not share a single lineage that is exclusive of other birds, but instead are descended independently from different lineages. Their shared characteristics would then be the result of convergent evolution
. An additional suggestion is that the Cathartidae (New World Vultures) are not Falconiformes at all, but are more closely related to the storks, and so belong either in the stork's order Ciconiiformes
, or in their own separate order, the Cathartiformes. However, morphological evidence supports the common ancestry of the Falconiformes, and the Strigiformes
(owls) may be very close to the Falconiformes as well. Furthermore, the family Horusornithidae
, a prehistoric family known only from fossils, seems to possess characteristics intermediate between hawks and falcons, suggesting they both evolved from a common ancestor similar to a Horusornithid.
The American Ornithologists' Union
provisionally reintegrated the New World vulture
s (family Cathartidae) into Falconiformes in 2007. This goes against the influential Sibley-Ahlquist taxonomy
, in which all the raptors are placed into Ciconiiformes, but the Cathartids are considered to be outside the lineage that includes other raptors. While the latter may be correct, the "Ciconiiformes" sensu Sibley and Ahlquist are a paraphyletic, artificial assemblage and one of the weakest points of their classification scheme.
Karyotype
analysis indicates that New World vultures are indeed distinct, and the Accipitridae stand apart from all other falconiform birds in that their microchromosome
s show a high degree of merging to medium-sized chromosome
s, which is unique in birds. Whether this has any bearing on the validity of the proposed Accipitriformes is still a matter of dispute, but it at least proves that the accipitrids are a monophyletic group.
There is a recent theory based on gene
studies that the falcon
s are more closely related to the parrot
s and passerine
s than to other birds including the Accipitridae
, and that thus the Falconiformes are not monophyletic even if the Cathartidae are excluded.
DNA
studies mean that it is likely to be some time until a consensus can be achieved.
(the possibly basal genus Masillaraptor
from the Messel Pit
). They typically have a sharply hooked beak
with a cere
(soft mass) on the proximodorsal surface, housing the nostril
s. Their wing
s are long and fairly broad, suitable for soaring flight, with the outer 4–6 primaries emarginated.
Falconiformes have strong legs and feet with raptor
ial claw
s and an opposable hind claw. Almost all Falconiformes are carnivorous
, hunting by sight during the day or at twilight. They are exceptionally long-lived, and most have low reproductive rates.
The young have a long, very fast-growing fledgling stage, followed by 3–8 weeks of nest care after first flight, and 1 to 3 years as sexually immature
adults. Females are bigger than males. Sexual dimorphism is generally most extreme in specialized bird-eaters, such as the Accipiter
hawks and Falco
falcons, in which a female may be more than twice as heavy as her mate; it borders on non-existent among the vulture
s. Monogamy
is the general rule, although an alternative mate is often selected if one dies.
Falconiformes are among the most diverse orders in size. The smallest species is believed to be the Black-thighed Falconet
, small males of which can weigh only 28 g (1 oz), measure 14 cm (5.5 inches) and have a wingspan of 26 cm (10.3 inches). The largest species is the Cinereous Vulture, at up to 14 kg (31 lbs), 118 cm (46 inches) and 3 m (10 feet) across the wings.
, or the Cathartidae placed in a still separate order, Cathartiformes.
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Falconiformes is a group of about 290 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s that comprises the diurnal birds of prey
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
. Raptor
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
classification is difficult and the order is treated in several ways.
Classification problems
Traditionally, all the raptors are grouped into four familiesFamily (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
in this single order. However, in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, it has become common to split the order into two: the falcon
Falcon
A falcon is any species of raptor in the genus Falco. The genus contains 37 species, widely distributed throughout Europe, Asia, and North America....
s and caracara
Caracara
Caracaras are birds of prey in the family Falconidae. They are traditionally placed in the subfamily Polyborinae, but are sometimes considered part of their own subfamily, Caracarinae, or members of the true falcon subfamily, Falconinae...
s remain in the order Falconiformes (about 60 species in 4 groups), and the remaining 220-odd species (including the Accipitridae
Accipitridae
The Accipitridae, one of the two major families within the order Accipitriformes , are a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a...
eagle
Eagle
Eagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
s, hawk
Hawk
The term hawk can be used in several ways:* In strict usage in Australia and Africa, to mean any of the species in the subfamily Accipitrinae, which comprises the genera Accipiter, Micronisus, Melierax, Urotriorchis and Megatriorchis. The large and widespread Accipiter genus includes goshawks,...
s, and many others) are put in the separate order Accipitriformes
Accipitriformes
The Accipitriformes is an order that has been proposed to include most of the diurnal birds of prey: hawks, eagles, vultures, and many others, about 225 species in all. For a long time, the majority view has been to include them with the falcons in the Falconiformes, but some authorities have...
. The idea that Falconiformes should be divided into smaller orders comes from the suggestion that the order may not share a single lineage that is exclusive of other birds, but instead are descended independently from different lineages. Their shared characteristics would then be the result of convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
. An additional suggestion is that the Cathartidae (New World Vultures) are not Falconiformes at all, but are more closely related to the storks, and so belong either in the stork's order Ciconiiformes
Ciconiiformes
Traditionally, the order Ciconiiformes has included a variety of large, long-legged wading birds with large bills: storks, herons, egrets, ibises, spoonbills, and several others. Ciconiiformes are known from the Late Eocene...
, or in their own separate order, the Cathartiformes. However, morphological evidence supports the common ancestry of the Falconiformes, and the Strigiformes
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...
(owls) may be very close to the Falconiformes as well. Furthermore, the family Horusornithidae
Horusornithidae
The Horusornithidae are a prehistoric family of birds of prey. They are part of the Falconiformes. Their name means "Horus-birds": the Egyptian god Horus was sometimes depicted as a falcon....
, a prehistoric family known only from fossils, seems to possess characteristics intermediate between hawks and falcons, suggesting they both evolved from a common ancestor similar to a Horusornithid.
The American Ornithologists' Union
American Ornithologists' Union
The American Ornithologists' Union is an ornithological organization in the USA. Unlike the National Audubon Society, its members are primarily professional ornithologists rather than amateur birders...
provisionally reintegrated the New World vulture
New World vulture
The New World Vulture or Condor family Cathartidae contains seven species in fivegenera, all but one of which are monotypic. It includes five vultures and two condors found in warm and temperate areas of the Americas....
s (family Cathartidae) into Falconiformes in 2007. This goes against the influential Sibley-Ahlquist taxonomy
Sibley-Ahlquist taxonomy
The Sibley-Ahlquist taxonomy is a bird taxonomy proposed by Charles Sibley and Jon Edward Ahlquist. It is based on DNA-DNA hybridization studies conducted in the late 1970s and throughout the 1980s....
, in which all the raptors are placed into Ciconiiformes, but the Cathartids are considered to be outside the lineage that includes other raptors. While the latter may be correct, the "Ciconiiformes" sensu Sibley and Ahlquist are a paraphyletic, artificial assemblage and one of the weakest points of their classification scheme.
Karyotype
Karyotype
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...
analysis indicates that New World vultures are indeed distinct, and the Accipitridae stand apart from all other falconiform birds in that their microchromosome
Microchromosome
A microchromosome is a type of very small chromosome which is a typical component of the karyotype of birds, some reptiles, fish, and amphibians; they tend to be absent in mammals. They are less than 20 Mb in size; chromosomes which are greater than 40 Mb in size are known as macrochromosomes,...
s show a high degree of merging to medium-sized chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
s, which is unique in birds. Whether this has any bearing on the validity of the proposed Accipitriformes is still a matter of dispute, but it at least proves that the accipitrids are a monophyletic group.
There is a recent theory based on gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
studies that the falcon
Falcon
A falcon is any species of raptor in the genus Falco. The genus contains 37 species, widely distributed throughout Europe, Asia, and North America....
s are more closely related to the parrot
Parrot
Parrots, also known as psittacines , are birds of the roughly 372 species in 86 genera that make up the order Psittaciformes, found in most tropical and subtropical regions. The order is subdivided into three families: the Psittacidae , the Cacatuidae and the Strigopidae...
s and passerine
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
s than to other birds including the Accipitridae
Accipitridae
The Accipitridae, one of the two major families within the order Accipitriformes , are a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a...
, and that thus the Falconiformes are not monophyletic even if the Cathartidae are excluded.
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...
studies mean that it is likely to be some time until a consensus can be achieved.
Characteristics
Falconiformes are known from the Middle EoceneEocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
(the possibly basal genus Masillaraptor
Masillaraptor
Masillaraptor is an extinct genus of basal falconiform from the Middle Eocene, a long-legged relative of the living falcons. Classifying the Falconiformes is confusing, since Europe has placed the families into two orders .- Etymology :Masillaraptor comes from the Latin word masilla, which is the...
from the Messel Pit
Messel pit
The Messel Pit is a disused quarry near the village of Messel, about southeast of Frankfurt am Main, Germany. Bituminous shale was mined there. Because of its abundance of fossils, it has significant geological and scientific importance...
). They typically have a sharply hooked beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
with a cere
Cère
The Cère is a long river in south-western France, left tributary of the Dordogne River. Its source is in the south-western Massif Central, near the mountain Plomb du Cantal...
(soft mass) on the proximodorsal surface, housing the nostril
Nostril
A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
s. Their wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...
s are long and fairly broad, suitable for soaring flight, with the outer 4–6 primaries emarginated.
Falconiformes have strong legs and feet with raptor
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
ial claw
Claw
A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...
s and an opposable hind claw. Almost all Falconiformes are carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
, hunting by sight during the day or at twilight. They are exceptionally long-lived, and most have low reproductive rates.
The young have a long, very fast-growing fledgling stage, followed by 3–8 weeks of nest care after first flight, and 1 to 3 years as sexually immature
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
adults. Females are bigger than males. Sexual dimorphism is generally most extreme in specialized bird-eaters, such as the Accipiter
Accipiter
The genus Accipiter is a group of birds of prey in the family Accipitridae, many of which are named as goshawks and sparrowhawks. They can be anatomically distinguished from their relatives by the lack of a procoracoid foramen. Two small and aberrant species usually placed here do possess a large...
hawks and Falco
Falcon
A falcon is any species of raptor in the genus Falco. The genus contains 37 species, widely distributed throughout Europe, Asia, and North America....
falcons, in which a female may be more than twice as heavy as her mate; it borders on non-existent among the vulture
Vulture
Vulture is the name given to two groups of convergently evolved scavenging birds, the New World Vultures including the well-known Californian and Andean Condors, and the Old World Vultures including the birds which are seen scavenging on carcasses of dead animals on African plains...
s. Monogamy
Monogamy
Monogamy /Gr. μονός+γάμος - one+marriage/ a form of marriage in which an individual has only one spouse at any one time. In current usage monogamy often refers to having one sexual partner irrespective of marriage or reproduction...
is the general rule, although an alternative mate is often selected if one dies.
Falconiformes are among the most diverse orders in size. The smallest species is believed to be the Black-thighed Falconet
Black-thighed Falconet
The Black-thighed Falconet is one of the smallest birds of prey, typically measuring between long. It is native to Brunei Darussalam, Myanmar, Thailand, Malaysia, Singapore and Indonesia....
, small males of which can weigh only 28 g (1 oz), measure 14 cm (5.5 inches) and have a wingspan of 26 cm (10.3 inches). The largest species is the Cinereous Vulture, at up to 14 kg (31 lbs), 118 cm (46 inches) and 3 m (10 feet) across the wings.
Systematics
Worldwide; 260 species; sometimes all families except Falconidae are separated as AccipitriformesAccipitriformes
The Accipitriformes is an order that has been proposed to include most of the diurnal birds of prey: hawks, eagles, vultures, and many others, about 225 species in all. For a long time, the majority view has been to include them with the falcons in the Falconiformes, but some authorities have...
, or the Cathartidae placed in a still separate order, Cathartiformes.
- FalconidaeFalconidaeThe falcons and caracaras are around 60 species of diurnal birds of prey that make up the family Falconidae. The family is divided into two subfamiles, Polyborinae, which includes the caracaras and forest falcons, and Falconinae, the falcons, kestrels and falconets.-Description:Falcons and...
: caracaraCaracaraCaracaras are birds of prey in the family Falconidae. They are traditionally placed in the subfamily Polyborinae, but are sometimes considered part of their own subfamily, Caracarinae, or members of the true falcon subfamily, Falconinae...
s, falconFalconA falcon is any species of raptor in the genus Falco. The genus contains 37 species, widely distributed throughout Europe, Asia, and North America....
s, falconets, hobbiesHobby (bird)A hobby is a fairly small, very swift falcon with long, narrow wings. There are four birds called hobby, and some others which, although termed falcon, are very similar. All specialise in being superb aerialists...
, kestrelKestrelThe name kestrel, is given to several different members of the falcon genus, Falco. Kestrels are most easily distinguished by their typical hunting behaviour which is to hover at a height of around over open country and swoop down on prey, usually small mammals, lizards or large insects...
s - Cathartidae: New World vultureNew World vultureThe New World Vulture or Condor family Cathartidae contains seven species in fivegenera, all but one of which are monotypic. It includes five vultures and two condors found in warm and temperate areas of the Americas....
s, condorCondorCondor is the name for two species of New World vultures, each in a monotypic genus. They are the largest flying land birds in the Western Hemisphere.They are:* The Andean Condor which inhabits the Andean mountains....
s - Pandionidae: OspreyOspreyThe Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...
- AccipitridaeAccipitridaeThe Accipitridae, one of the two major families within the order Accipitriformes , are a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a...
: buzzards, eagleEagleEagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
s, harrierHarrier (bird)A harrier is any of the several species of diurnal hawks forming the Circinae sub-family of the Accipitridae family of birds of prey. Harriers characteristically hunt by flying low over open ground, feeding on small mammals, reptiles, or birds....
s, hawkHawkThe term hawk can be used in several ways:* In strict usage in Australia and Africa, to mean any of the species in the subfamily Accipitrinae, which comprises the genera Accipiter, Micronisus, Melierax, Urotriorchis and Megatriorchis. The large and widespread Accipiter genus includes goshawks,...
s, kiteKite (bird)Kites are raptors with long wings and weak legs which spend a great deal of time soaring. Most feed mainly on carrion but some take various amounts of live prey.They are birds of prey which, along with hawks and eagles, are from the family Accipitridae....
s, Old World vultureOld World vultureOld World vultures belong to the family Accipitridae, which also includes eagles, buzzards, kites, and hawks.Old World vultures are not closely related to the superficially similar New World vultures and condors, and do not share that group's good sense of smell. The similarities between the two...
s - Sagittaridae: Secretary BirdSecretary BirdThe Secretarybird or Secretary Bird is a large, mostly terrestrial bird of prey. Endemic to Africa, it is usually found in the open grasslands and savannah of the sub-Sahara...
External links
- http://www.eeb.cornell.edu/winkler/botw/falconiformes.html
- Eaglewatch: Birds of prey and owls around the world (in Dutch; click on "Language / Taal" at top right for the English version)