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 (singular remex) while those on the tail are called rectrices (singular rectrix). The Red Kite ( Milvus milvus) is a medium-large Bird of prey in the family Accipitridae, which also includes many other diurnal raptors such Feathers are one of the epidermal growths that form the distinctive outer covering or Plumage, on Birds They are considered the most complex integumentary structures WING "ESPN 1410" is a commercial AM radio station in Dayton Ohio operating with 5000 watts at 1410 kHz with studios offices and transmitter located on David The tail is the section at the rear end of an Animal 's Body; in general the term refers to a distinct flexible Appendage to the Torso. Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. Their primary function is to aid in the generation of both thrust and lift, thereby enabling flight. Thrust is a reaction force described quantitatively by Newton 's Second and Third Laws. In the context of a Fluid flow relative to a body the lift force is the component of the Aerodynamic force that is Perpendicular to the flow Flight is the main mode of locomotion used by most of the world's bird species The flight feathers of some birds have evolved to perform additional functions, generally associated with territorial displays, courtship rituals or feeding methods. In some species, these feathers have developed into long showy plumes used in visual courtship displays, while in others they create a sound during display flights. Tiny serrations on the leading edge of their remiges help owls to fly silently (and therefore hunt more successfully), while the extra-stiff rectrices of woodpeckers help them to brace against tree trunks as they hammer. The Owls are an order of birds of prey. Most are Solitary, and nocturnal, with some exceptions (e The woodpeckers, piculets and wrynecks are a family, Picidae, of Near-passerine Birds. Even flightless birds still retain flight feathers, though sometimes in radically modified forms.

The moult of their flight feathers can cause serious problems for birds, as it can impair their ability to fly. Different species have evolved different strategies for coping with this, ranging from dropping all their flight feathers at once (and thus becoming flightless for some relatively short period of time) to extending the moult over a period of several years.

Contents 1 Remiges 1.1 Primaries 1.2 Secondaries 1.3 Tertials 1.4 Emargination 1.5 Alula 1.6 Delayed development in Hoatzins 2 Rectrices 3 Numbering conventions 4 Specialized flight feathers 5 Vestigiality in flightless birds 6 Moult 7 Age differences in flight feathers 8 Wing formula 9 Primary extension 10 See also 11 Notes 12 References 13 External links

Remiges

Remiges (from the Latin for "oarsman") are located on the posterior side of the wing. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species Ligaments attach the long calami, or quills, firmly to the wing bones, and a thick, strong band of tendinous tissue—known as the postpatagium—helps to hold and support the remiges in place. In Anatomy, the term ligament is used to denote three different types of structures Fibrous tissue that connects Bones to other bones Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce A tendon (or sinew) is a tough band of Fibrous connective tissue that usually connects Muscle to Bone and is capable of withstanding tension ^[1] Corresponding remiges on individual birds are symmetrical between the two wings, matching to a large extent in size and shape (except in the case of mutation or damage), though not necessarily in pattern. Symmetry generally conveys two primary meanings The first is an imprecise sense of harmonious or aesthetically-pleasing proportionality and balance such that it reflects beauty or In biology mutations are changes to the Nucleotide sequence of the Genetic material of an organism ^[2][3] They are given different names depending on their position along the wing.

Primaries

Primaries are connected to the manus (the bird's "hand", composed of carpometacarpus and phalanges); these are the longest and narrowest of the remiges (particularly those attached to the phalanges), and they can be individually rotated. The manus ( Latin for Hand) is the zoological term for the distal portion of the fore limb of an animal The name Phalanx (plural phalanges) is commonly given to the Bones that form Fingers and Toes In Primates such as Humans These feathers are especially important for flapping flight, as they are the principal source of thrust, moving the bird forward through the air. Thrust is a reaction force described quantitatively by Newton 's Second and Third Laws. Most thrust is generated on the downstroke of flapping flight. However, on the upstroke (when the bird often draws its wing in close to its body), the primaries are separated and rotated, reducing air resistance while still helping to provide some thrust. ^[4] The flexibility of the remiges on the wingtips of large soaring birds also allows for the spreading of those feathers, which helps to reduce the creation of wingtip vortices, thereby reducing drag. V erification of the O rigins of R otation in T ornadoes Ex periment or VORTEX, is a field project that seeks to understand how a In Fluid dynamics, drag (sometimes called fluid resistance) is the force that resists the movement of a Solid object through a Fluid (a ^[5]

Species vary somewhat in the number of primaries they possess. The Bald Eagle ( Haliaeetus leucocephalus) is a Bird of prey found in North America that is most recognizable as the national bird and Flight is the main mode of locomotion used by most of the world's bird species The number in non-passerines generally varies between 9 and 11,^[6] but grebes, storks and flamingos have 12,^[7] and ostriches have 16. Grebes are members of the Podicipediformes order, a widely distributed order of freshwater diving birds some of which visit the sea when migrating Storks are large long-legged long-necked wading Birds with long stout bills, belonging to the family Ciconiidae. Flamingos or flamingoes ( are gregarious Wading birds in the Genus Phoenicopterus and family The Ostrich ( Struthio camelus) is a large Flightless bird native to Africa (and formerly the Middle East) ^[7] While most modern passerines have ten primaries,^[6] some have only nine. Those with nine are missing the most distal primary (sometimes called the remicle) which is typically very small and sometimes rudimentary in passerines. ^[7]

The outermost primaries—those connected to the phalanges—are sometimes known as pinions.

Secondaries

Secondaries are connected to the ulna. The Common Buzzard ( Buteo buteo) is a medium to large Bird of prey, whose range covers most of Europe and extends into Asia. The ulna ( elbow bone) is a long bone prismatic in form placed at the medial side of the Forearm, parallel with the radius. In some species, the ligaments that bind these remiges to the bone connect to small, rounded projections, known as quill knobs, on the ulna; in other species, no such knobs exist. Secondary feathers remain close together in flight (they cannot be individually separated like the primaries can) and help to provide lift by creating the airfoil shape of the bird's wing. Secondaries tend to be shorter and broader than primaries, with blunter ends (see illustration). They vary in number from 6 in hummingbirds to as many as 40 in some species of albatross. Hummingbirds are Birds in the family Trochilidae, and are endemic to the Americas. Albatrosses, of the biological family Diomedeidae, are large Seabirds allied to the procellariids, Storm-petrels and Diving-petrels ^[8] In general, larger and longer-winged species have a larger number of secondaries. ^[8] Birds in more than 40 non-passerine families seem to be missing the fifth secondary feather on each wing, a state known as diastataxis. ^[9] In these birds, the fifth set of secondary covert feathers does not cover any remex, possibly due to a twisting of the feather papillae during embryonic development. An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular ^[9] Loons, grebes, pelicans, hawks and eagles, cranes, sandpipers, gulls, parrots, and owls are among the families missing this feather. The loons (eg North America or divers (eg UK/Ireland are a group of aquatic birds found in many parts of North America and northern Eurasia Grebes are members of the Podicipediformes order, a widely distributed order of freshwater diving birds some of which visit the sea when migrating A pelican is a large water Bird with a distinctive pouch under the beak belonging to the Bird family Pelecanidae. The term hawk can be used in several ways In strict usage in Europe and Asia, to mean any of the Species in the Subfamily Cranes are large long-legged and long-necked Birds of the order Gruiformes, and family Gruidae. "Sandpiper" redirects here For the 1965 film see The Sandpiper. Gulls (often informally Seagulls) are birds in the family Laridae Parrots are birds of the roughly 350 Species in 85 genera comprising the order Psittaciformes, found in most warm and tropical regions The Owls are an order of birds of prey. Most are Solitary, and nocturnal, with some exceptions (e

Tertials

Tertials are connected to the humerus in some species. The humerus is a Long bone in the Arm or Forelimb that runs from the Shoulder to the Elbow. These elongated "true" tertials act as a protective cover for all or part of the folded primaries and secondaries, and do not qualify as flight feathers as such. ^[10] However, many authorities use the term tertials to refer to the shorter, more symmetrical innermost secondaries of passerines (which perform the same function as true tertials) in an effort to distinguish them from the other secondaries.

Emargination

The outermost primaries of large soaring birds, particularly raptors, often show a pronounced narrowing at some variable distance along the feather edges. These narrowings are called either notches or emarginations depending on the degree of their slope. ^[9] An emargination is a gradual change, and can be found on either side of the feather. A notch is an abrupt change, and is only found on the wider trailing edge of the remige. (Both are visible on the primary in the photo showing the feathers; they can be found about halfway along both sides of the left hand feather—a shallow notch on the left, and a gradual emargination on the right. ) The presence of notches and emarginations creates gaps at the wingtip; air is forced through these gaps, increasing the generation of lift. ^[11]

Alula

Feathers on the alula or bastard wing are not generally considered to be flight feathers in the strict sense; though they are asymmetrical, they lack the length and stiffness of most true flight feathers. The Mallard ( Anas platyrhynchos) probably the best-known and most recognizable of all ducks is a Dabbling duck which breeds throughout the Temperate This article is about the Alula feather For the Finnish ornithological journal of the same name see Alula (journal; for the Hawaiian plant see Brighamia This article is about the Alula feather For the Finnish ornithological journal of the same name see Alula (journal; for the Hawaiian plant see Brighamia However, alula feathers are definitely an aid to slow flight. These feathers—which are attached to the bird's "thumb" and normally lie flush against the anterior edge of the wing—function in the same way as the slats on an airplane wing, allowing the wing to achieve a higher than normal angle of attack – and thus lift – without resulting in a stall. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species Slats is also a nickname for Australian cricketer Michael Slater, and NHL executive Glen Sather Slats are Aerodynamic Angle of attack ( AOA, \alpha Greek letter alpha) is a term used in Aerodynamics to describe the Angle between the In the context of a Fluid flow relative to a body the lift force is the component of the Aerodynamic force that is Perpendicular to the flow For other uses see Stall. In Aerodynamics, a stall is a sudden reduction in the lift forces generated by an Airfoil By manipulating its thumb to create a gap between the alula and the rest of the wing, a bird can avoid stalling when flying at low speeds or landing. ^[9]

Delayed development in Hoatzins

The development of the remiges (and alula) of nestling Hoatzins is much delayed compared to the development of these feathers in other young birds, presumably because young Hoatzins are equipped with claws on their first two digits. The Hoatzin ( Opisthocomus hoazin) also known as the Hoactzin, Stinkbird, or Canje "Pheasant", is an unusual species A claw is a curved pointed appendage found at the end of a toe or finger in most Mammals, Birds, and some Reptiles. A finger is a type of digit, an organ of manipulation and sensation found in the Hands of Humans and other Primates Normally humans have five digits They use these small rounded hooks to grasp branches when clambering about in trees, and feathering on these digits would presumably interfere with that functionality. Most youngsters shed their claws sometime between their 70^th and 100^th day of life, but some retain them—though callused-over and unusable—into adulthood. A callus (or Callosity) is an especially toughened area of Skin which has become relatively thick and hard as a response to repeated contact or pressure ^[12][13]

Rectrices

Rectrices (from the Latin for "helmsman"), which help the bird to brake and steer in flight, lie in a single horizontal row on the rear margin of the anatomical tail. Only the central pair are attached (via ligaments) to the tail bones; the remaining rectrices are embedded into the rectricial bulbs, complex structures of fat and muscle that surround those bones. In Anatomy, the term ligament is used to denote three different types of structures Fibrous tissue that connects Bones to other bones Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce Pope's nose redirects here It may also refer to the license plate light on early Volkswagen Beetles Pygostyle refers to a number of the Rectrices are always paired, with a vast majority of species having six pairs. They are absent in grebes and some ratites, and greatly reduced in size in penguins. A ratite is any of a diverse group of large Flightless birds of Gondwanan origin most of them now extinct Penguins ( order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless Birds living almost ^{[7][14][15][16]} Many grouse species have more than 12 rectrices; some (including Ruffed Grouse and Hazel Grouse) have a number that varies between individuals. Grouse are a group of birds from the order Galliformes. Often considered a family Tetraonidae, the American Ornithologists' Union The Ruffed Grouse, Bonasa umbellus, is a medium-sized Grouse occurring in forests from the Appalachian Mountains across Canada The Hazel Grouse or Hazel Hen ( Bonasa bonasia) is one of the smaller members of the Grouse family of Birds. ^[17] Domestic pigeons have a highly variable number, due to centuries of selective breeding. The domestic pigeon ( Columba livia f domestica) was derived from the Rock Pigeon. ^[18]

Numbering conventions

In order to make the discussion of such topics as moult processes or body structure easier, ornithologists assign a number to each flight feather. In Biology, moulting (or molting, also known as shedding or for some species Ecdysis) signifies the manner in which an animal routinely With regard to living things, a body is the integral physical material of an individual Ornithology (from Greek ὄρνις ὄρνιθος ornis, ornithos, "bird" and λόγος logos, "knowledge" is the branch of A number is an Abstract object, tokens of which are Symbols used in Counting and measuring. By convention, the numbers assigned to primary feathers always start with the letter P (P1, P2, P3, etc. ), those of secondaries with the letter S, those of tertials with T and those of rectrices with R.

Most authorities number the primaries descendantly, starting from the innermost primary (the one closest to the secondaries) and working outwards; others number them ascendantly, from the most distal primary inwards. ^[6] There are some advantages to each method. Descendant numbering follows the normal sequence of most birds' primary moult. In addition, in the event that a species is missing the small distal 10^th primary, as some passerines are, its lack does not impact the numbering of the remaining primaries. Ascendant numbering, on the other hand, allows for uniformity in the numbering of non-passerine primaries, as they almost invariably have four attached to the manus regardless of how many primaries they have overall. ^[6] This method is particularly useful for indicating wing formulae, as the outermost primary is the one with which the measurements begin.

Secondaries are always numbered ascendantly, starting with the outermost secondary (the one closest to the primaries) and working inwards. ^[6] Tertials are also numbered ascendantly, but in this case, the numbers continue on consecutively from that given to the last secondary (e. g. … S5, S6, T7, T8, … etc. ). ^[6]

Rectrices are always numbered from the centermost pair outwards in both directions. ^[19]

Specialized flight feathers

The flight feathers of some species have undergone evolutionary changes which allow them to provide additional functionality. The Pin-tailed Whydah, Vidua macroura, is a small Songbird. It is a resident breeding bird in most of Africa south of the Sahara Desert.

In some species, for example, either remiges or rectrices make a sound during flight. These sounds are most often associated with courtship or territorial displays. The outer primaries of male Broad-tailed Hummingbirds produce a distinctive high-pitched trill, both in direct flight and in power-dives during courtship displays; this trill is diminished when the outer primaries are worn, and absent when those feathers have been moulted. Male (♂ refers to the sex of an organism or part of an organism which produces small mobile Gametes called spermatozoa. The Broad-tailed hummingbird, Selasphorus platycercus, is a medium-sized Hummingbird, nearly four inches (10 cm in length ^[20] During the Northern Lapwing's zigzagging display flight, the bird's outer primaries produce a humming sound. ^[21] The outer primaries of the male American Woodcock are shorter and slightly narrower than those of the female, and are likely the source of the whistling and twittering sounds made during his courtship display flights. The American Woodcock, Scolopax minor, is a small chunky shorebird Species from North America. ^[22] Male Club-winged Manakins use modified secondaries to make a clear trilling courtship call. The Club-winged Manakin ( Machaeropterus deliciosus) is a small Passerine Bird which is a resident breeding species in the cloud forest on A curve-tipped secondary on each wing is dragged against an adjacent ridged secondary at high speeds (as many as 100 times per second—twice as fast as a hummingbird's wingbeat) to create a stridulation much like that produced by some insects. Stridulation is the act of producing Sound by rubbing together certain body parts ^[23] Both Wilson's and Common Snipe have modified outer tail feathers which make noise when they are spread during the birds' roller coaster display flights; as the bird dives, wind flows through the modified feathers and creates a series of rising and falling notes, which is known as "winnowing". Wilson's Snipe ( Gallinago delicata) is a small stocky shorebird. The Common Snipe or Fantail Snipe ( Gallinago gallinago) is a small stocky shorebird. ^[24] Differences between the sounds produced by these two former conspecific subspecies—and the fact that the outer two pairs of rectrices in Wilson's Snipe are modified, while only the single outermost pair are modified in Common Snipe—were among the characteristics used to justify their splitting into two distinct and separate species.

Flight feathers are also used by some species in visual displays. Male Standard-winged and Pennant-winged Nightjars have modified P2 primaries (using the descendant numbering scheme explained above) which are displayed during their courtship rituals. The Standard-winged Nightjar, Macrodipteryx longipennis, is a Bird in the Nightjar family The Pennant-winged Nightjar is an intra African migrant that occurs from Nigeria to northern South Africa ^[25] In the Standard-winged Nightjar, this modified primary consists of an extremely long shaft with a small "pennant" (actually a large web of barbules) at the tip. In the Pennant-winged Nightjar, the P2 primary is an extremely long (but otherwise normal) feather, while P3, P4 and P5 are successively shorter; the overall effect is a broadly-forked wingtip with a very long plume beyond the lower half of the fork.

Males of many species, ranging from the widely introduced Ring-necked Pheasant to Africa's many whydahs, have one or more elongated pairs of rectrices, which play an often-critical role in their courtship rituals. The Common Pheasant ( Phasianus colchicus) is a bird in the Pheasant family (Phasianidae See also Whydah Gally for the Pirate ship and Ouidah for the town in Benin. The outermost pair of rectrices in male lyrebirds are extremely long and strongly curved at the ends. A Lyrebird is either of two Species of ground-dwelling Australian Birds most notable for their superb ability to mimic natural and artificial These plumes are raised up over the bird's head (along with a fine spray of modified uppertail coverts) during his extraordinary display. Rectrix modification reaches its pinnacle among the birds of paradise, which display an assortment of often bizarrely modified feathers, ranging from the extremely long plumes of the Ribbon-tailed Astrapia (nearly three times the length of the bird itself) to the dramatically coiled twin plumes of the Magnificent Bird of Paradise. The birds of paradise are members of the family Paradisaeidae of the order Passeriformes. The Ribbon-tailed Astrapia, Astrapia mayeri is a medium-sized up to 32cm long velvet black Bird of paradise. The Magnificent Bird of Paradise, Cicinnurus magnificus is a small up to 26cm-long Bird of paradise with extremely complex plumage

Owls have remiges which are serrated rather than smooth on the leading edge. The Owls are an order of birds of prey. Most are Solitary, and nocturnal, with some exceptions (e This adaptation disrupts the flow of air over the wings, eliminating the noise that airflow over a smooth surface normally creates, and allowing the birds to fly silently. ^[26]

The rectrices of woodpeckers are proportionately short and very stiff, allowing them to better brace themselves against tree trunks while feeding. The woodpeckers, piculets and wrynecks are a family, Picidae, of Near-passerine Birds. This adaptation is also found, though to a lesser extent, in some other species that feed along tree trunks, including woodcreepers and treecreepers. The woodcreepers ( Dendrocolaptinae) comprise a Subfamily of Sub-oscine Passerine Birds endemic to the Neotropics The treecreepers (Certhiidae are a family of small Passerine birds widespread in wooded regions of the Northern Hemisphere and Sub-Saharan Africa

Scientists have not yet determined the function of all flight feather modifications. For instance, male swallows in the genera Psalidoprocne and Stelgidopteryx have tiny recurved hooks on the leading edges of their outer primaries, but the function of these hooks is not yet known; some authorities suggest they may produce a sound during territorial or courtship displays. ^[27]

Vestigiality in flightless birds

Over time, a small number of bird species have lost their ability to fly. The Southern Cassowary, Casuarius casuarius, also known as Double-wattled Cassowary or Two-wattled Cassowary, is a large flightless black bird with Some of these, such as the flightless steamer ducks, show no appreciable changes in their flight feathers. Tachyeres ( Steamer Ducks)is a Genus of Ducks in the Bird family Anatidae. Some, such as the Titicaca Flightless Grebe and a number of the flightless rails, have a reduced number of primaries. "Centropelma" redirects here This was also also the initial preoccupied name of the Spider genus Nicodamus. ^[28]

The remiges of ratites are soft and downy; they lack the interlocking hooks and barbules that help to stiffen the flight feathers of other birds. In addition, the Emu's remiges are proportionately much reduced in size, while those of the cassowaries are reduced both in number and structure, consisting merely of 5–6 bare quills. The Emu ( Dromaius novaehollandiae, is the largest Bird native to Australia and the only extant member of the Genus Cassowaries ( Genus Casuarius) are very large flightless Birds native to the Tropical forests of New Guinea and Most ratites have completely lost their rectrices; only the Ostrich still has them.

Penguins have lost their differentiated flight feathers. Penguins ( order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless Birds living almost As adults, their wings and tail are covered with the same small, stiff, slightly curved feathers as are found on the rest of their bodies.

The ground-dwelling Kakapo, which is the world's only flightless parrot, has remiges which are shorter, rounder and more symmetrically vaned than those of parrots capable of flight; these flight feathers also contain fewer interlocking barbules near their tips. The Kakapo ( Māori: kākāpō, meaning night parrot) Strigops habroptilus (from the Greek strix, genitive Parrots are birds of the roughly 350 Species in 85 genera comprising the order Psittaciformes, found in most warm and tropical regions ^[29]

Moult

Once they have finished growing, feathers are essentially dead structures. The Jackdaw ( Corvus monedula) sometimes known as the Eurasian Jackdaw, European Jackdaw or caddow, is one of the smallest species (34–39  Over time, they become worn and abraded, and need to be replaced. This replacement process is known as moult (molt in the United States). In Biology, moulting (or molting, also known as shedding or for some species Ecdysis) signifies the manner in which an animal routinely The loss of wing and tail feathers can affect a bird's ability to fly (sometimes dramatically) and in certain families can impair the ability to feed or perform courtship displays. In Biological classification, family ( Latin Courtship is the traditional dating period before engagement and marriage The timing and progression of flight feather moult therefore varies between families.

For most birds, moult begins at a certain specific point, called a focus (plural foci), on the wing or tail and proceeds in a sequential manner in one or both directions from there. For example, most passerines have a focus between the innermost primary (P1, using the numbering scheme explained above) and outermost secondary (S1), and a focus point in the middle of the center pair of rectrices. ^[30] As passerine moult begins, the two feathers closest to the focus are the first to drop. When replacement feathers reach roughly half of their eventual length, the next feathers in line (P2 and S2 on the wing, and both R2s on the tail) are dropped. This pattern of drop and replacement continues until moult reaches either end of the wing or tail. The speed of the moult can vary somewhat within a species. Some passerines that breed in the Arctic, for example, drop many more flight feathers at once (sometimes becoming briefly flightless) in order to complete their entire wing moult prior to migrating south, while those same species breeding at lower latitudes undergo a more protracted moult. The Arctic is the Region around the Earth 's North Pole, opposite the Antarctic region around the South Pole. Bird migration refers to the regular seasonal journeys undertaken by many species of Birds Bird movements include those made in response to changes in food availability Latitude, usually denoted symbolically by the Greek letter phi ( Φ) gives the location of a place on Earth (or other planetary body north or south of the ^[31]

In many species, there is more than one focus along the wing. The White-bellied Sea-eagle ( Haliaeetus leucogaster) and also known as the White-bellied Fish-eagle or White-breasted Sea Eagle, is a large Here, moult begins at all foci simultaneously, but generally proceeds only in one direction. Most grouse, for example, have two wing foci: one at the wingtip, the other between feathers P1 and S1. In this case, moult proceeds descendantly from both foci. Many large, long-winged birds have multiple wing foci.

Birds that are heavily "wing-loaded"—that is, heavy-bodied birds with relatively short wings—have great difficulty flying with the loss of even a few flight feathers. A protracted moult like the one described above would leave them vulnerable to predators for a sizeable portion of the year. A year (from Old English gēr) is the time between two recurrences of an event related to the Orbit of the Earth around the Sun Instead, these birds lose all their flight feathers at once. This leaves them completely flightless for a period of three to four weeks, but means their overall period of vulnerability is significantly shorter than it would otherwise be. A week (also called sennight or sevennight) is a unit of Time longer than a Day and shorter than a Month. Eleven families of birds, including loons, grebes and most waterfowl, have this moult strategy. The loons (eg North America or divers (eg UK/Ireland are a group of aquatic birds found in many parts of North America and northern Eurasia The order Anseriformes contains about 150 living Species of Birds in three extant families the Anhimidae (the screamers Anseranatidae

Arboreal woodpeckers, which depend on their tails—particularly the strong central pair of rectrices—for support while they feed, have a unique tail moult. The woodpeckers, piculets and wrynecks are a family, Picidae, of Near-passerine Birds. Rather than moulting their central tail feathers first, as most birds do, they retain these feathers until last. Instead the second pair of rectrices (both R2 feathers) are the first to drop. (In some species in the genera Celeus and Dendropicos, the third pair is the first dropped. ) The pattern of feather drop and replacement proceeds as described for passerines (above) until all other rectrices have been replaced; only then are the central tail rectrices moulted. This provides some protection to the growing feathers, since they're always covered by at least one existing feather, and also ensures that the bird's newly strengthened tail is best able to cope with the loss of the crucial central rectrices. Ground-feeding woodpeckers, such as the wrynecks, do not have this modified moult strategy; in fact, wrynecks moult their outer tail feathers first, with moult proceeding proximally from there. The wrynecks (genus Jynx) are a small but distinctive group of small Old World Woodpeckers Like the true woodpeckers wrynecks have large In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species

Age differences in flight feathers

There are often substantial differences between the remiges and rectrices of adults and juveniles of the same species. Because all juvenile feathers are grown at once—a tremendous energy burden to the developing bird—they are softer and of poorer quality than the equivalent feathers of adults, which are moulted over a longer period of time (as long as several years in some cases). ^[32] As a result, they wear more quickly.

As feathers grow at variable rates, these variations lead to visible dark and light bands in the fully formed feather. These so called growth bars and their widths have been used to determine the daily nutritional status of birds. Each light and dark bar correspond to around 24 hours and the use of this technique has been called ptilochronology (analogous to dendrochronology). Dendrochronology (from Greek grc δένδρον dendron, "tree" grc χρόνος khronos, "time" and grc -λογία ^[33][34]

In general, juveniles have feathers which are narrower and more sharply-pointed at the tip. ^[35][36] This can be particularly visible when the bird is in flight, especially in the case of raptors. The trailing edge of the wing of a juvenile bird can appear almost serrated, due to the feathers' sharp tips, while that of an older bird will be straighter-edged. ^[35] The flight feathers of a juvenile bird will also be uniform in length, since they all grew at the same time. Those of adults will be of various lengths and levels of wear, since each is moulted at a different time. ^[32]

The flight feathers of adults and juveniles can differ considerably in length, particularly among the raptors. Overall, juveniles tend to have slightly longer rectrices, and shorter, broader wings (with shorter outer primaries, and longer inner primaries and secondaries) than do adults of the same species. ^[37] However, there are many exceptions. In longer-tailed species, such as Swallow-tailed Kite, Secretary Bird and European Honey Buzzard, for example, juveniles have shorter rectrices than adults do. The Swallow-tailed Kite ( Elanoides forficatus) is an Elanid kite which breeds from the southeastern United States to eastern Peru The Secretary Bird, Sagittarius serpentarius, is a large mostly terrestrial Bird of prey. The Honey Buzzard ( Pernis apivorus) sometimes known as the "pern" is a Bird of prey in the family Accipitridae which also includes many other Juveniles of some Buteo buzzards have narrower wings than adults do, while those of large juvenile falcons are longer.

Experts theorize that the differences help young birds compensate for their inexperience, weaker flight muscles and poorer flying ability. ^[37]

Wing formula

A wing formula describes the shape of distal end of a bird's wing in a mathematical way. Mathematics is the body of Knowledge and Academic discipline that studies such concepts as Quantity, Structure, Space and It can be used to help distinguish between species with similar plumages, and thus is particularly useful for those who ring (band) birds. Bird ringing (also known as bird Banding) is an aid to studying wild Birds by attaching a small individually numbered metal or plastic ring to their legs ^[9]

To determine a bird's wing formula, the distance between the tip of the most distal primary and the tip of its greater covert (the longest of the feathers that cover and protect the shaft of that primary) is measured in millimeters. In some cases, this results in a positive number (e. g. , the primary extends beyond its greater covert), while in other cases it's a negative number (e. g. the primary is completely covered by the greater covert, as happens in some passerine species). Next, the longest primary feather is identified, and the differences between the length of that primary and that of all remaining primaries and of the longest secondary are also measured, again in millimeters. If any primary shows a notch or emargination, this is noted, and the distance between the feather's tip and any notch is measured, as is the depth of the notch. All distance measurements are made with the bird's wing closed, so as to maintain the relative positions of the feathers.

While there can be considerable variation across members of a species—and while the results are obviously impacted by the effects of moult and feather regeneration—even very closely related species show clear differences in their wing formulas. ^[9]

Primary extension

The distance that a bird's longest primaries extend beyond its longest secondaries (or tertials) when its wings are folded is referred to as the primary extension or primary projection. ^[38] As with wing formulae, this measurement is useful for distinguishing between similarly plumaged birds; however, unlike wing formulae, it isn't necessary to have the bird in-hand to make the measurement. Rather, this is a useful relative measurement—some species have long primary extensions, while others have shorter ones. Among the Empidonax flycatchers of the Americas, for example, the Dusky Flycatcher has a much shorter primary extension than does the very similarly-plumaged Hammond's Flycatcher. The genus Empidonax is a group of small insect-eating Passerine Birds in the Tyrant flycatcher family the Tyrannidae The tyrant flycatchers ( Tyrannidae) are a family of Passerine Birds which occur throughout North and South America, but are mainly The Americas are the lands of the Western hemisphere or New World, consisting of the Continents of North America and South America The Dusky Flycatcher, Empidonax oberholseri, is a small insect-eating Bird of the Tyrant flycatcher family Hammond's Flycatcher, Empidonax hammondii is a small insect-eating Bird. ^[38] Europe's Common Skylark has a long primary projection, while that of the near-lookalike Oriental Skylark is very short. The Skylark ( Alauda arvensis) is a small Passerine Bird species The Oriental Skylark ( Alauda gulgula) also known as the Oriental Lark or Small Skylark, is a species of Skylark found in South Asia ^[39]

See also

• Bird anatomy
• Bird flight
• Drumming (snipe)
• Pinioning
• Plumage

Notes

References

• Campbell, Bruce & Lack, Elizabeth, eds. (1985), A Dictionary of Birds, Carlton, England: T and A D Poyser, ISBN 0-85661-039-9 
• del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi, eds. (1992), Handbook of the Birds of the World, Volume 1: Ostrich to Ducks, Barcelona: Lynx Edicions, ISBN 84-87334-10-5 
• Grubb, T. HBW_-_Taxonomygif|right|frame|(400 × 258 pixels file size38KBMIME typeimage/gif|HBW-Page on Taxonomy]]HBW-accounts_8-082-083_copia C. (1989), “Ptilochronology: feather growth bars as indicators of nutritional status. ”, Auk 106: 314–320 
• del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi, eds. (1997), Handbook of the Birds of the World, Volume 4: Sandgrouse to Cuckoos, Barcelona: Lynx Edicions, ISBN 84-87334-22-9 
• del Hoyo, Josep; Elliott, Andrew & Christie, David, eds. (2004), Handbook of the Birds of the World, Volume 9: Cotingas to Pipits and Wagtails, Barcelona: Lynx Edicions, ISBN 84-87334-69-5 
• Ehrlich, Paul R.; Dobkin, Darryl A. Paul Ralph Ehrlich (born May 29 1932 in Philadelphia Pennsylvania) is a renowned Entomologist specializing in Lepidoptera (butterflies ; Wheye, Darryl & Pimm, Stuart L. (1994), The Birdwatcher's Handbook, Oxford University Press, ISBN 0-19-858407-5 
• Ferguson-Lees, James & Christie, David A. (2001), Raptors of the World, London: Christopher Helm, ISBN 0-7136-8026-1 
• Forsman, Dick (1999), The Raptors of Europe and the Middle East, London: T and A D Poyser, ISBN 0-85661-098-4 
• Jenni, Lukas & Winkler, Raffael (1994), Moult and Ageing of European Passerines, London: Academic Press, ISBN 0-12-384150-X 
• Paulson, Dennis (2005), Shorebirds of North America, London: Christopher Helm, ISBN 0-7136-7377-X 
• Shawkey, Matthew D. ; Beck, Michelle L. & Hill, Geoffrey E. (2003), “Use of a gel documentation system to measure feather growth bars. ”, J. Field Ornithol. 74 (2): 125–128 
• Sibley, David (2001), The Sibley Guide to Bird Life & Behaviour, London: Christopher Helm, ISBN 0-7136-6250-6 
• Trail, Pepper (2001), Wing Feathers, U. David Allen Sibley (born 1962, New York) is an American ornithologist. S. Fish and Wildlife Service, <http://www.lab.fws.gov/idnotes/WingFeathers-prnt.pdf>. Retrieved on 30 May 2008 

External links

• Wing Feathers—US Fish and Wildlife Service document Contains excellent photographic examples of emargination and notching in raptor remiges.
• Video of feeding Magellanic Woodpecker (Campephilus magellanicus) Shows use of rectrices for bracing.
• Video of singing male Superb Lyrebird (Menuta novaehollandiae) Shows long modified rectrices which are used in display (though the video doesn't show full display).
• Video of male Club-winged Manakin (Machaeropterus deliciosus) Shows use of secondary remiges to produce sound.
• Cornell Laboratory of Ornithology's American Woodcock (Scolopax minor) recordings #94216 has a good example of the sounds made by remiges during courtship display flight, starting at about 2:32.
• Sound made by rectrices in courtship flight of Common Snipe (Gallinago gallinago)

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