97-568: The white-starred robin ( Pogonocichla stellata ) is a species of bird in the Old World flycatcher and chat family Muscicapidae . It is also sometimes more simply called the starred robin . It is monotypic within the genus Pogonocichla . There are around twelve subspecies. The species is found in East and southern Africa . It is a forest species, occurring in montane forest in the north of its range but closer to sea level further south. This
194-728: A better sense of smell. A third stage of bird evolution starting with Ornithothoraces (the "bird-chested" avialans) can be associated with the refining of aerodynamics and flight capabilities, and the loss or co-ossification of several skeletal features. Particularly significant are the development of an enlarged, keeled sternum and the alula , and the loss of grasping hands. † Anchiornis † Archaeopteryx † Xiaotingia † Rahonavis † Jeholornis † Jixiangornis † Balaur † Zhongjianornis † Sapeornis † Confuciusornithiformes † Protopteryx † Pengornis Ornithothoraces † Enantiornithes Flight feather Flight feathers ( Pennae volatus ) are
291-442: A clear trilling courtship call. A curve-tipped secondary on each wing is dragged against an adjacent ridged secondary at high speeds (as many as 110 times per second—slightly faster than a hummingbird's wingbeat) to create a stridulation much like that produced by some insects. 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
388-473: A definition similar to "all theropods closer to birds than to Deinonychus ", with Troodon being sometimes added as a second external specifier in case it is closer to birds than to Deinonychus . Avialae is also occasionally defined as an apomorphy-based clade (that is, one based on physical characteristics). Jacques Gauthier , who named Avialae in 1986, re-defined it in 2001 as all dinosaurs that possessed feathered wings used in flapping flight , and
485-442: A group called Paraves . Some basal members of Deinonychosauria, such as Microraptor , have features which may have enabled them to glide or fly. The most basal deinonychosaurs were very small. This evidence raises the possibility that the ancestor of all paravians may have been arboreal , have been able to glide, or both. Unlike Archaeopteryx and the non-avialan feathered dinosaurs, who primarily ate meat, studies suggest that
582-511: A large extent in size and shape (except in the case of mutation or damage), though not necessarily in the pattern. They are given different names depending on their position along the wing. 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. These feathers are especially important for flapping flight, as they are
679-528: A more protracted moult. In many species, there is more than one focus along the wing. 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
776-440: A silvery edge to the flight feathers , finally chirindensis is brighter yellow-green on the back. The white-starred robin is a principally found in primary or secondary moist evergreen forest. It needs forest with a good understory of shrubs and vines. It also occupies forest edges, pine and wattle plantations, evergreen woodlands and forest edge gardens. It occasionally is reported in bamboo or heath zones in some mountains. In
873-406: A sister group, the order Crocodilia , contain the only living representatives of the reptile clade Archosauria . During the late 1990s, Aves was most commonly defined phylogenetically as all descendants of the most recent common ancestor of modern birds and Archaeopteryx lithographica . However, an earlier definition proposed by Jacques Gauthier gained wide currency in the 21st century, and
970-501: A sound during territorial or courtship displays. Over time, a small number of bird species have lost their ability to fly. Some of these, such as the steamer ducks , show no appreciable changes in their flight feathers. Some, such as the Titicaca grebe and a number of the flightless rails, have a reduced number of primaries. The remiges of ratites are soft and downy; they lack the interlocking hooks and barbules that help to stiffen
1067-433: A state known as diastataxis (those that do have the fifth secondary are said to be eutaxic). In these birds, the fifth set of secondary covert feathers does not cover any remiges, possibly due to a twisting of the feather papillae during embryonic development. Loons , grebes, pelicans , hawks and eagles , cranes , sandpipers , gulls , parrots, and owls are among the families missing this feather. Tertials arise in
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#17327977053441164-717: A time, sometimes for years, and rarely for life. Other species have breeding systems that are polygynous (one male with many females) or, rarely, polyandrous (one female with many males). Birds produce offspring by laying eggs which are fertilised through sexual reproduction . They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds being important sources of eggs, meat, and feathers. Songbirds , parrots, and other species are popular as pets. Guano (bird excrement)
1261-406: Is a brightly coloured robin with a bright yellow breast and belly, a slate coloured head with spots on the eyes and throat and blueish wings. The white-starred robin gives a range of calls that vary geographically. The diet is dominated by insects, although some fruit is taken as well. It is a territorial and seasonal breeder that lays up to three eggs in a domed nest. The generic name Pogoncichla
1358-457: Is also found, though to a lesser extent, in some other species that feed along tree trunks, including treecreepers and woodcreepers . Scientists have not yet determined the function of all flight feather modifications. 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
1455-411: Is broad and black, and unlike other robin species, is surrounded by well-developed rictal bristles used in flycatching. Juvenile birds are blackish-brown above with golden flecks, and yellow with brown scaling below. The nominate race has a sub-adult plumage, which is dusky olive above, yellow breast and belly, with grey streaks, and the tail is as adult but brownish instead of black. This sub-adult plumage
1552-540: Is called ornithology . Birds are feathered theropod dinosaurs and constitute the only known living dinosaurs . Likewise, birds are considered reptiles in the modern cladistic sense of the term, and their closest living relatives are the crocodilians . Birds are descendants of the primitive avialans (whose members include Archaeopteryx ) which first appeared during the Late Jurassic . According to recent estimates, modern birds ( Neornithes ) evolved in
1649-531: Is called saltatory or transilient wing moults. In simple forms, this involves the moulting and replacement of odd-numbered primaries and then the even-numbered primaries. There are however complex variations with differences based on life history. Arboreal woodpeckers , which depend on their tails—particularly the strong central pair of rectrices—for support while they feed, have a unique tail moult. Rather than moulting their central tail feathers first, as most birds do, they retain these feathers until last. Instead,
1746-510: Is derived from the Greek pogon for beard , a reference to the white spots on the throat and face, and kikhle for thrush. Similarly the specific name stellata and the species' common name are also derived from the facial spots. The white-starred robin is related to the chats , subfamily Saxicolinae , a group formerly placed with the thrush family Turdidae, but now placed in the Old World flycatcher family Muscicapidae . Its position within
1843-493: Is diminished when the outer primaries are worn, and absent when those feathers have been moulted. During the northern lapwing 's zigzagging display flight, the bird's outer primaries produce a humming sound. 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. Male club-winged manakins use modified secondaries to make
1940-429: Is harvested for use as a fertiliser. Birds figure throughout human culture. About 120 to 130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry. The first classification of birds
2037-473: Is known as moult (molt in the United States). 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 . The timing and progression of flight feather moult therefore varies among families. For most birds, moult begins at a certain specific point, called a focus (plural foci), on
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#17327977053442134-660: Is moulted at a different time. The flight feathers of adults and juveniles can differ considerably in length, particularly among the raptors. 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. 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. Juveniles of some Buteo buzzards have narrower wings than adults do, while those of large juvenile falcons are longer. It
2231-503: Is not considered a direct ancestor of birds, though it is possibly closely related to the true ancestor. Over 40% of key traits found in modern birds evolved during the 60 million year transition from the earliest bird-line archosaurs to the first maniraptoromorphs , i.e. the first dinosaurs closer to living birds than to Tyrannosaurus rex . The loss of osteoderms otherwise common in archosaurs and acquisition of primitive feathers might have occurred early during this phase. After
2328-486: Is referred to as the primary extension or primary projection. As with wing formulae, this measurement is useful for distinguishing between similarly plumaged birds; however, unlike wing formulae, it is not 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
2425-430: Is retained for up to two years. The race pallidiflava is as the nominate, but with a paler yellow on the breast and belly. intensa is quite different, with a bronze-washed back, a yellow rump and slate edges on the flight feathers. The race ruwenzori is like intensa but with a deeper yellow on the breast. The race elgonensis is as nominate but with an all black tail, the subadult of this species has some yellow on
2522-410: Is synonymised with the nominate race. In Bowie's 2006 study of the genetics of the northern subspecies intensa and pallidiflava were treated as a single subspecies, keniensis . The white-starred robin is a small robin, 15 to 16 cm (5.9–6.3 in) in length and weighing between 18 and 25 g (0.63–0.88 oz), with the females being slightly smaller than the males. The plumage of
2619-516: Is synonymous to Avifilopluma. † Scansoriopterygidae † Eosinopteryx † Jinfengopteryx † Aurornis † Dromaeosauridae † Troodontidae Avialae Based on fossil and biological evidence, most scientists accept that birds are a specialised subgroup of theropod dinosaurs and, more specifically, members of Maniraptora , a group of theropods which includes dromaeosaurids and oviraptorosaurs , among others. As scientists have discovered more theropods closely related to birds,
2716-410: Is theorized that the differences help young birds compensate for their inexperience, weaker flight muscles and poorer flying ability. A wing formula describes the shape of distal end of a bird's wing in a mathematical way. It can be used to help distinguish between species with similar plumages, and thus is particularly useful for those who ring (band) birds. To determine a bird's wing formula,
2813-535: Is used by many scientists including adherents to the PhyloCode . Gauthier defined Aves to include only the crown group of the set of modern birds. This was done by excluding most groups known only from fossils , and assigning them, instead, to the broader group Avialae, on the principle that a clade based on extant species should be limited to those extant species and their closest extinct relatives. Gauthier and de Queiroz identified four different definitions for
2910-722: The Late Cretaceous and diversified dramatically around the time of the Cretaceous–Paleogene extinction event 66 million years ago, which killed off the pterosaurs and all non- ornithuran dinosaurs. Many social species preserve knowledge across generations ( culture ). Birds are social, communicating with visual signals, calls, and songs , and participating in such behaviour as cooperative breeding and hunting, flocking , and mobbing of predators. The vast majority of bird species are socially (but not necessarily sexually) monogamous , usually for one breeding season at
3007-669: The Tiaojishan Formation of China, which has been dated to the late Jurassic period ( Oxfordian stage), about 160 million years ago. The avialan species from this time period include Anchiornis huxleyi , Xiaotingia zhengi , and Aurornis xui . The well-known probable early avialan, Archaeopteryx , dates from slightly later Jurassic rocks (about 155 million years old) from Germany . Many of these early avialans shared unusual anatomical features that may be ancestral to modern birds but were later lost during bird evolution. These features include enlarged claws on
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3104-581: The class Aves ( Latin: [ˈaveːs] ), characterised by feathers , toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart , and a strong yet lightweight skeleton . Birds live worldwide and range in size from the 5.5 cm (2.2 in) bee hummingbird to the 2.8 m (9 ft 2 in) common ostrich . There are over 11,000 living species and they are split into 44 orders . More than half are passerine or "perching" birds. Birds have wings whose development varies according to species;
3201-433: The olecranon and performing the same function as true tertials) in an effort to distinguish them from other secondaries. The term humeral is sometimes used for birds such as the albatrosses and pelicans that have a long humerus. The calami of the flight feathers are protected by a layer of non-flight feathers called covert feathers or tectrices (singular tectrix ), at least one layer of them both above and beneath
3298-716: The Latin word for "helmsman", help the bird to brake and steer in flight. These feathers lie in a single horizontal row on the rear margin of the anatomic 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. 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. Many grouse species have more than 12 rectrices. In some species (including ruffed grouse , hazel grouse and common snipe ),
3395-418: 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 . In general, larger and longer-winged species have a larger number of secondaries. Birds in more than 40 non-passerine families seem to be missing the fifth secondary feather on each wing,
3492-428: The appearance of Maniraptoromorpha, the next 40 million years marked a continuous reduction of body size and the accumulation of neotenic (juvenile-like) characteristics. Hypercarnivory became increasingly less common while braincases enlarged and forelimbs became longer. The integument evolved into complex, pennaceous feathers . The oldest known paravian (and probably the earliest avialan) fossils come from
3589-682: The bird dives, wind flows through the modified feathers and creates a series of rising and falling notes, which is known as "winnowing". 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
3686-405: 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. 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
3783-444: 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 . 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. The development of
3880-404: 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. There are often substantial differences between the remiges and rectrices of adults and juveniles of
3977-454: 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. The distance that a bird's longest primaries extend beyond its longest secondaries (or tertials) when its wings are folded
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4074-509: The birds that descended from them. Despite being currently one of the most widely used, the crown-group definition of Aves has been criticised by some researchers. Lee and Spencer (1997) argued that, contrary to what Gauthier defended, this definition would not increase the stability of the clade and the exact content of Aves will always be uncertain because any defined clade (either crown or not) will have few synapomorphies distinguishing it from its closest relatives. Their alternative definition
4171-451: The brachial region and are not considered true remiges as they are not supported by attachment to the corresponding bone, in this case the humerus. 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. However, many authorities use the term tertials to refer to the shorter, more symmetrical innermost secondaries of passerines (arising from
4268-427: The breeding season is September to December. White-starred robins are territorial breeders, with the territories varying in size from 0.5 to 0.75 ha. The nest is unusual for the family in that it is a domed construction, built out of dead leaves, rootlets, moss and tendrils, and lined with leaf skeletons and fine plant material. The nest is well hidden, usually on sloping ground against a trunk or rock, but sometimes off
4365-609: The carpal joint) was formerly thought to be absent in some species, but the modern view of this diastataxy is that there is a gap between the fourth and fifth secondaries. Tertiary feathers growing upon the adjoining portion of the brachium are not considered true remiges. 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
4462-463: The centermost pair outwards in both directions. The flight feathers of some species provide additional functionality. 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
4559-456: The descendant numbering scheme explained above) which are displayed during their courtship rituals. 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;
4656-453: 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 is a negative number (e.g. the primary is completely covered by the greater covert, as happens in some passerine species). Next,
4753-504: The dramatically coiled twin plumes of the magnificent bird-of-paradise . Owls have remiges which are serrated rather than smooth on the leading edge. 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 and hunt silently. The rectrices of woodpeckers are proportionately short and very stiff, allowing them to better brace themselves against tree trunks while feeding. This adaptation
4850-665: The earliest members of Aves, is removed from this group, becoming a non-avian dinosaur instead. These proposals have been adopted by many researchers in the field of palaeontology and bird evolution , though the exact definitions applied have been inconsistent. Avialae, initially proposed to replace the traditional fossil content of Aves, is often used synonymously with the vernacular term "bird" by these researchers. † Coelurus † Ornitholestes † Ornithomimosauria † Alvarezsauridae † Oviraptorosauria Paraves Most researchers define Avialae as branch-based clade, though definitions vary. Many authors have used
4947-412: The ends. 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
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#17327977053445044-443: The event that a species is missing the small distal 10th 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. This method is particularly useful for indicating wing formulae, as
5141-511: The family is somewhat uncertain; along with three other monotypic African robin genera it is thought to have affinities with the robin-chats in the genus Cossypha , and it is sometimes placed close to the Swynnerton's robin ( Swynnertonia ). The taxonomy within the species is highly complex, as across its range it has some subspecies with intermediate plumages between juveniles and adults, and in some not. There are also different songs across
5238-413: The feather edges. These narrowings are called either notches or emarginations depending on the degree of their slope. 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 remex. (Both are visible on the primary in the photo showing the feathers; they can be found about halfway along both sides of
5335-451: The first avialans were omnivores . The Late Jurassic Archaeopteryx is well known as one of the first transitional fossils to be found, and it provided support for the theory of evolution in the late 19th century. Archaeopteryx was the first fossil to display both clearly traditional reptilian characteristics—teeth, clawed fingers, and a long, lizard-like tail—as well as wings with flight feathers similar to those of modern birds. It
5432-437: The flight feathers is to aid in the generation of both thrust and lift , thereby enabling flight . The flight feathers of some birds 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
5529-415: 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. Most ratites have completely lost their rectrices; only the ostrich still has them. Penguins have lost their differentiated flight feathers. As adults, their wings and tail are covered with
5626-407: The flight feathers of the wings as well as above and below the rectrices of the tail. These feathers may vary widely in size – in fact, the upper tail tectrices of the male peafowl , rather than its rectrices, are what constitute its elaborate and colorful "train". The outermost primaries of large soaring birds, particularly raptors, often show a pronounced narrowing at some variable distance along
5723-418: The fully formed feather. These 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 ). In general, juveniles have feathers which are narrower and more sharply pointed at the tip. This can be particularly visible when
5820-793: The genus Arthroleptis ). The white-starred robin is a seasonal breeder, although the exact timing varies across its range. Birds have been recorded breeding or seen in breeding condition in August to May in the DR Congo, August to November in Rwanda. They in all month in East Africa, but with an attitudinal shift insofar as lowland birds prefer the wet season and highland birds breed in the dry season. In Zambia they breed from September to June, but only from September to January in Malawi. In South Africa
5917-530: The ground on a rotting trunk rock or earth bank. The nest takes seven days to construct, and is built by the female alone. Between two and three eggs are laid, with two being more common in the tropics and three being typical further south. Eggs are laid on consecutive days with incubation only beginning once the final egg has been laid. Incubation is carried out by the female alone. Incubation lasts between 16 and 18 days, after which chicks fledge around 13 to 15 days after hatching. The chicks remain dependent upon
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#17327977053446014-407: 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 on them. Even flightless birds still retain flight feathers, though sometimes in radically modified forms. The remiges are divided into primary and secondary feathers based on their position along
6111-541: 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. 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. However, alula feathers are definitely an aid to slow flight. These feathers—which are attached to
6208-414: 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. There are some advantages to each method. Descendant numbering follows the normal sequence of most birds' primary moult. In
6305-465: The long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges ( / ˈ r ɛ m ɪ dʒ iː z / ), singular remex ( / ˈ r iː m ɛ k s / ), while those on the tail are called rectrices ( / ˈ r ɛ k t r ɪ s iː z / or / r ɛ k ˈ t r aɪ s iː z / ), singular rectrix ( / ˈ r ɛ k t r ɪ k s / ). The primary function of
6402-404: 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
6499-528: 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. 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. Eleven families of birds, including loons , grebes and most waterfowl , have this moult strategy. The cuckoos show what
6596-422: The moult over a period of several years. Remiges (from the Latin for "oarsman") are located on the posterior side of the wing. Ligaments attach the long calami (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. Corresponding remiges on individual birds are symmetrical between the two wings, matching to
6693-570: 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
6790-420: The nominate race is slate-grey on the head, with a white spot in front of each eye and another small one on the throat. The mantle and part of the wings are green (moss-green in the mantle, olive-green on the wings), the rest of the wings are bluish grey, and the tail is black with yellow lateral stripes. The breast and belly are bright yellow, and the legs are pinkish. The plumage of both sexes are alike. The bill
6887-530: The nominate race, is a disyllabic " too-twii ", the second type, used by macarthuri , helleri and transvaalensis is a more complex multisyllabic " ter-whe dada wiiyoo " or " wheh chiiyoo wher-ter-weh techiiyoo ". The white-starred robin feeds principally on insects and fruits. In one study of fecal samples conducted in KwaZulu-Natal in South Africa, beetles , moths and ants predominated in
6984-499: The northern parts of its range, near the equator, it occurs in mountains between 1,500 and 2,200 m (4,900–7,200 ft) in elevation (sometimes as high as 3,300 m (10,800 ft)), further south in Zimbabwe it seldom occur above 1,300 m (4,300 ft), and in South Africa it can occur at sea level. The white-starred robin is a partial migrant . This migration is altitudinal, with birds moving to lower altitudes during
7081-450: The number of primaries they possess. The number in non-passerines generally varies between 9 and 11, but grebes , storks and flamingos have 12, and ostriches have 16. While most modern passerines have ten primaries, 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. The outermost primaries—those connected to
7178-452: The number varies among individuals. Domestic pigeons have a highly variable number as a result of changes brought about over centuries of selective breeding. In order to make the discussion of such topics as moult processes or body structure easier, ornithologists assign a number to each flight feather. By convention, the numbers assigned to primary feathers always start with the letter P (P1, P2, P3, etc.) , those of secondaries with
7275-523: The only known groups without wings are the extinct moa and elephant birds . Wings, which are modified forelimbs , gave birds the ability to fly, although further evolution has led to the loss of flight in some birds , including ratites , penguins , and diverse endemic island species. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds , have further evolved for swimming. The study of birds
7372-402: The outermost half) can be seen in the evolution of maniraptoromorphs, and this process culminated in the appearance of the pygostyle , an ossification of fused tail vertebrae. In the late Cretaceous, about 100 million years ago, the ancestors of all modern birds evolved a more open pelvis, allowing them to lay larger eggs compared to body size. Around 95 million years ago, they evolved
7469-418: 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. 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.). Rectrices are always numbered from
7566-418: 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 outermost pair of rectrices in male lyrebirds are extremely long and strongly curved at
7663-505: The parents for up to 42 days after hatching. Nests are raided by small mammals such as shrews and rodents , as well as more rarely by large mammals like civets and monkeys . They are also targeted by brood parasites , principally red-chested cuckoos (six out of 85 nests checked in South Africa) but also other species like African emerald cuckoos . Bird Birds are a group of warm-blooded vertebrates constituting
7760-423: The phalanges—are sometimes known as pinions . Secondaries are connected to the ulna . 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
7857-536: The previously clear distinction between non-birds and birds has become blurred. By the 2000s, discoveries in the Liaoning Province of northeast China, which demonstrated many small theropod feathered dinosaurs , contributed to this ambiguity. The consensus view in contemporary palaeontology is that the flying theropods, or avialans , are the closest relatives of the deinonychosaurs , which include dromaeosaurids and troodontids . Together, these form
7954-426: The principal source of thrust , moving the bird forward through the air. The mechanical properties of primaries are important in supporting flight. 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. The flexibility of
8051-585: The remiges (and alulae) 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 . 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 70th and 100th day of life, but some retain them— though callused -over and unusable— into adulthood. Rectrices (singular rectrix) from
8148-410: 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 . The barbules on these feathers, friction barbules, are specialized with large lobular barbicels that help grip and prevent slippage of overlying feathers and are present in most of the flying birds. Species vary somewhat in
8245-452: The same biological name "Aves", which is a problem. The authors proposed to reserve the term Aves only for the crown group consisting of the last common ancestor of all living birds and all of its descendants, which corresponds to meaning number 4 below. They assigned other names to the other groups. Lizards & snakes Turtles Crocodiles Birds Under the fourth definition Archaeopteryx , traditionally considered one of
8342-524: The same small, stiff, slightly curved feathers as are found on the rest of their bodies. The ground-dwelling kākāpō , 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. Once they have finished growing, feathers are essentially dead structures. Over time, they become worn and abraded, and need to be replaced. This replacement process
8439-415: 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). As a result, they wear more quickly. As feathers grow at variable rates, these variations lead to visible dark and light bands in
8536-483: The samples, being found 83%, 58% and 43% of the time respectively. Other remains found included those of spiders, flies, caterpillars, amphipods, true bugs, wasps, grasshoppers and centipedes. The remains of fruit were found in 34% of the samples, with Canthium , Cassipourea , Ficus , Hedychium , Ilex , Kiggelaria and Rhus being found. The species has also been recorded feeding on other species, including snails, termites, mantids and even small frogs (of
8633-492: 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
8730-551: The second toe which may have been held clear of the ground in life, and long feathers or "hind wings" covering the hind limbs and feet, which may have been used in aerial maneuvering. Avialans diversified into a wide variety of forms during the Cretaceous period. Many groups retained primitive characteristics , such as clawed wings and teeth, though the latter were lost independently in a number of avialan groups, including modern birds (Aves). Increasingly stiff tails (especially
8827-410: The subspecies and in particular two types of pipping call which have a patchwork distribution across the range and between the subspecies. At present twelve subspecies are recognised: Several other races have been described; friedmanni , which is synonymised with ruwenzorii , lebombo , from the border of South Africa and Eswatini, which is synonymised with transvaalensis , and margaritata , which
8924-401: The tail, macarthuri is more pale below and has a deeper greenish-olive back. The race helleri has a green back and yellow rump, whereas the rump of orientalis is green, as well as having greyish wings and more greenish yellow-upper wings. The race hygrica is as nominate but with a saturated moss-green back, and the race transvaalensis is as hygrica but more orange yellow below and with
9021-466: 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. 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,
9118-418: The wing. There are typically 11 primaries attached to the manus (six attached to the metacarpus and five to the phalanges), but the outermost primary, called the remicle, is often rudimentary or absent; certain birds, notably the flamingos, grebes, and storks, have seven primaries attached to the metacarpus and 12 in all. Secondary feathers are attached to the ulna. The fifth secondary remex (numbered inwards from
9215-428: The winter (April to September), and is much more pronounced in the southern parts of the range. In Malawi birds descend to the shores of lake Malawi (300 m (980 ft)), birds in South Africa and Mozambique move as low as sea-level, and may move 120 km (75 mi) from their breeding sites. In Malawi studies established that the males remained in their breeding territories , while the females moved away during
9312-443: The winter. The calls and songs of the white-starred robin are geographically variable. Both sexes sing the territorial advertising song, which is a quiet song sung from near the ground. The courtship call is sung during a display flight, and is rendered as a sustained " wiii wii wiii ". The loud contact call, also used as a warning call, varies by subspecies. The first type, used by intensa , ruwenzori , guttifer , orientalis and
9409-466: Was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae . Carl Linnaeus modified that work in 1758 to devise the taxonomic classification system currently in use. Birds are categorised as the biological class Aves in Linnaean taxonomy . Phylogenetic taxonomy places Aves in the clade Theropoda as an infraclass or a subclass, more recently a subclass. Aves and
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