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Bird Tail
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Flight feather
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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). Their primary function is to aid in the generation of both thrust and lift, thereby enabling flight. 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. Even flightless birds still retain flight feathers, though sometimes in radically modified forms.
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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.
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Remiges
Remiges (from the Latin for "oarsman") are located on the posterior side of the wing. 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. 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. They are given different names depending on
their position along the wing.
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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. These feathers are especially important for flapping flight, as they are the principal source of thrust,
moving the bird forward through the air. 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.[5] 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.
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The outermost primaries—those connected to the phalanges—are sometimes known as pinions.
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Tertials
Tertials are connected to the humerus in some species. 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 (which perform the same function as true tertials) in an effort to distinguish them from the other secondaries.
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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. 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
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