The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator and padding, used in goods such as jackets, bedding (duvets and featherbeds), pillows and sleeping bags. The discovery of feathers trapped in ancient amber suggests that some species of non-avian dinosaur likely possessed down-like feathers.
The word down comes from the Old Norse word dúnn, which had the same meaning as its modern equivalent. [1] The down feather is considered to be the most "straightforward" of all feather types. [2] It has a short or vestigial rachis (shaft), few barbs, and barbules that lack hooks. [3] There are three types of down: natal down, body down and powder down. Natal down is the layer of down feathers that cover most birds at some point in their early development. Precocial nestlings are already covered with a layer of down when they hatch, while altricial nestlings develop their down layer within days or weeks of hatching. Megapode hatchlings are the sole exception; they are already covered with contour feathers when they hatch. [4] : 470 Body down is a layer of small, fluffy feathers that lie underneath the outer contour feathers on a bird's body. [5]
Powder down, or pulviplumes, is a special type of down that occurs in a few groups of apparently unrelated birds. In some species, the tips of the barbules on powder down feathers disintegrate, forming fine particles of keratin, which appear as a powder, or "feather dust", among the feathers. These feathers grow continuously and are not moulted. [6] In other species, powder grains come from cells that surround the barbules of growing feathers. [4] : 208 These specialized feathers are typically scattered among ordinary down feathers, though in some species, they occur in clusters. [3] All parrots have powder down, with some species (including the mealy amazons) producing copious amounts. [7] It is also found in herons and tinamous. [3] The dust produced from powder down feathers is a known allergen in humans. [8]
The loose structure of down feathers traps air, which helps to insulate the bird against heat loss [5] and contributes to the buoyancy of waterbirds. Species that experience annual temperature fluctuations typically have more down feathers following their autumn moult. [9] There is some evidence that down feathers may also help to decrease the incidence of nestling cannibalism among some colonially nesting species, as the stiffness of the feathers make the young more difficult to swallow. [9] Pollutants can reduce the efficiency of these functions. When oiled, for example, down feathers mat and clump together, which breaks down the bird's insulation and allows water to reach the skin. [10]
Female wildfowl use down feathers plucked from their own breasts to line their scrape nests. This process performs the dual function of helping to insulate the eggs and exposing the female's brood patch—an area of bare skin, rich in blood vessels, which transmits heat very efficiently. [11] Of the various items birds use to line their nests, down feathers provide the most effective insulation, though only when dry; wet down is the least effective insulator. [12] Down may also help camouflage the eggs when the female is away from the nest, particularly as the birds often draw the feathers over their eggs before leaving. [13]
Because a bird can eliminate heavy metals in its feathers and because feathers can be collected non-invasively and stored indefinitely, down feathers can be used to check for evidence of metal contamination in the bird's environment. Studies have shown a high level of correlation between the level of metal contamination in a bird's diet and the level found in its feathers, with the proportion of the chemicals found in its feathers remaining relatively constant (and relatively high for some metals). [14]
Mutations in the genes that control the formation of down feathers have been recorded in a German White Leghorn chicken flock. Although the elements of a normal down feather are present, a hyperkeratosis of the feather's horny sheath after 16–17 days of incubation results in the sheath not splitting as it should during the final stages of the feather's growth. Because of that abnormal splitting, the bird's down appears to be matted; chicks with this condition look bristly and singed and tend to be lighter in body weight than normal chicks are. [15]
Down feathers are used by Indigenous North Americans for religious ceremonies and as powerful symbols. In the stories of some cultures, the down feathers of an eagle are important gifts given by the bird to the story's hero. [16] In the Ghost Dance, a religious movement that has become particularly widespread among the Indigenous peoples of the Great Plains and Canadian Prairies, each dancer holds a painted feather tipped with a down feather painted with another color; the feathers are generally those of a crow, which is sacred to the Ghost Dance, or an eagle, which is ubiquitously sacred. [17] Zuni prayer sticks are also made using eagle down. While eagle feathers belong to the Sun Priest, who plants them to the sun, other priests could use them if rain was needed, as the down is said to suggest "fleecy clouds that gather on the horizon before rain". The Hopi rub eagle down feathers over rattlesnakes collected for Snake Dances, in an effort to soothe and calm the reptiles. [18]
Anglers who fly fish have long used the down feathers of waterfowl for the construction of fishing lures. Because they are white, down feathers can be easily dyed a variety of colours. They are used to make the bodies, tails and wing casings of the flies. [19] Historically, much of the down used for the flies came from the wing and tail of the marabou stork; these feathers were also popular with the millinery and dressmaking trades. [20] [21] Though it is still called by the same name, today's "marabou" (sometimes spelled "marabout"), comes from domestic turkeys, as marabou storks are protected. [22]
For centuries, humans across the globe have used down feathers for insulation. Russian documents from the 1600s list "bird down" among the goods sold to Dutch merchants, [23] and communities in northern Norway began protecting the nests of eider ducks as early as 1890. [24] Eiders are still "farmed" by people in Iceland, Scandinavia and Siberia. The birds are provided with nest sites and protected from predators, and down is collected intermittently during the nesting season without harming the nests or female ducks. The first collection is made roughly halfway through the incubation period, when some 0.75 oz (21 g) of high quality down is removed per nest. When the eggs have hatched and the young have left the area, the remaining down and breast feathers are gathered, typically resulting in another 0.75 oz (21 g) of lower quality feathers per nest. [23] In general, 50–60 nests will produce about one kilogram (2.2 pounds) of down feathers. [25] No more than four tonnes of eiderdown is collected from wild nests each year. [26] [27] Approximately 70% of that harvest is from Iceland. [28] According to the International Down and Feather Bureau, eiderdown contributes only a small, but lucrative, portion of the world's total down production, estimated at 175,000 tonnes annually. [26] An eiderdown duvet requires from 600 to 1,600 grams of eiderdown fill; a simple 800 gram duvet sells for about 640,000 Icelandic króna (US$5,116) as of 2021. [26]
In Iceland and Scandinavia, colonies of more than 5,000 birds sometimes develop in "farmed" areas, while in some protected areas of the Novaya Zemlya archipelago, nest densities exceed 13,000 per hectare (5,300/acre). [23] On the other hand, the more nomadic indigenous peoples of Arctic Canada did not see down production as a reasonable source of income and tended to overexploit eider nests with "indifferent" collection of down feathers from the nests. [29] Although the down feathers of various species of wildfowl, gulls and other seabirds have historically been used for insulation, most now come from domestic geese. [24] Some 70 percent of the world's supply comes from China, typically from birds killed for their meat. Most of the rest comes from Europe and Canada, from birds harvested for meat or pâté. [30]
A portion of the world's supply of down feathers are plucked from live birds, [31] a practice condemned as cruel by animal welfare groups. [32] The precise percentage of down harvested in this manner is uncertain; while some references report that it is only a small fraction of the total (less than 1% in 2011), [31] a 2009 Swedish documentary reported that it might be as much as 50–80% of the total supply, a figure supported by IKEA and an industry representative, but disputed by organizations within the industry. [33] [34] The documentary also shows birds lying on the floor with large flesh wounds from the plucking, after which the wounds were stitched using a needle and thread without anesthetic. [35] Although live-plucking is illegal in Canada, the United States and Europe, it is known to occur in two European countries (Poland and Hungary) and in China. [32] Public sentiment against the practice has, in some countries, been strong. IKEA and clothing manufacturer Patagonia have altered product lines to eliminate the use (or possible use) of live-plucked down. [36] [37]
In the United States, Federal Trade Commission regulations require that any product labeled "100% Down" must contain only down feathers, while products labeled simply "Down" can contain a mixture of fiber and feathers. In addition, products labeled as "Goose Down" must contain at least 90% goose down, 10% goose feathers. [27] Down insulation is rated by fill power, which is the number of cubic inches displaced by a given ounce of down (in3/oz). To measure fill power, an ounce of down is placed into a graduated cylinder, and a small weight is dropped in on top of it; the volume below the weight indicates the fill power. Eiderdown has the highest fill power, at 1200.[ citation needed ] However, even down with a fill power as low as 550 still provides reasonably good insulation. [27] Higher fill-power downs will thus insulate better than lower fill-power downs of the same weight. Insulation in most outdoor equipment ranges from about 400 to 900 in3/oz (230–520 cm3/g). Down rated 500–650 in3/oz (290–380 cm3/g) is warm enough and light enough for most conditions, and 800–900 in3/oz (460–520 cm3/g) fill is used for very lightweight and/or very cold-weather gear.
Down is warm, lightweight and packable. If well cared for, it retains its loft up to three times longer than do most synthetics. [38] However, when it is wet, the thermal properties of down are virtually eliminated. Down forms clumps if exposed to dampness or moisture, and will mildew if left damp. In addition, it will absorb and retain odors. [39]
Down feathers tend to become more allergenic as they age, as they become contaminated with molds and dust mites. Pillows provide the most common source of exposure, though mattresses, comforters, outerwear and upholstery can also cause problems. [40] A Finnish study has shown that true feather allergies are rare, with most issues caused by dust mites. [41]
Feathers found in amber in western France, Canada and northeastern China suggest that some non-avian dinosaurs may have had primitive, down-like feathers. [42] [43]
The Labrador duck is an extinct North American duck species. It has the distinction of being the first known endemic North American bird species to become extinct after the Columbian Exchange, with the last known sighting occurring in 1878 in Elmira, New York. It was already a rare duck before European settlers arrived, and as a result of its rarity, information on the Labrador duck is not abundant, although some, such as its habitat, characteristics, dietary habits and reasons behind its extinction, are known. There are 55 specimens of the Labrador duck preserved in museum collections worldwide.
Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and an example of a complex evolutionary novelty. They are among the characteristics that distinguish the extant birds from other living groups.
The common eider, also called St. Cuthbert's duck or Cuddy's duck, is a large sea-duck that is distributed over the northern coasts of Europe, North America and eastern Siberia. It breeds in Arctic and some northern temperate regions, but winters somewhat farther south in temperate zones, when it can form large flocks on coastal waters. It can fly at speeds up to 113 km/h (70 mph).
The marabou stork is a large wading bird in the stork family Ciconiidae native to sub-Saharan Africa. It breeds in both wet and arid habitats, often near human habitation, especially landfill sites. It is sometimes called the "undertaker bird" due to its shape from behind: cloak-like wings and back, skinny white legs, and sometimes a large white mass of "hair". It has often been credited with the largest wingspan of any land bird, with an average of 2.6 metres (8.5 ft) and some recorded examples of up to 3.2 metres (10 ft).
The king eider is a large sea duck that breeds along Northern Hemisphere Arctic coasts of northeast Europe, North America and Asia. The birds spend most of the year in coastal marine ecosystems at high latitudes, and migrate to Arctic tundra to breed in June and July. They lay four to seven eggs in a scrape on the ground lined with grass and down.
Steller's eider is a migrating Arctic diving duck that breeds along the coastlines of eastern Russia and Alaska. It is the rarest, smallest, and fastest flying of the eider species.
The fulvous whistling duck or fulvous tree duck is a species of whistling duck that breeds across the world's tropical regions in much of Mexico and South America, the West Indies, the southern United States, sub-Saharan Africa and the Indian subcontinent. It has plumage that is mainly reddish brown, long legs and a long grey bill, and shows a distinctive white band across its black tail in flight. Like other members of its ancient lineage, it has a whistling call which is given in flight or on the ground. Its preferred habitat consists of wetlands with plentiful vegetation, including shallow lakes and paddy fields. The nest, built from plant material and unlined, is placed among dense vegetation or in a tree hole. The typical clutch is around ten whitish eggs. The breeding adults, which pair for life, take turns to incubate, and the eggs hatch in 24–29 days. The downy grey ducklings leave the nest within a day or so of hatching, but the parents continue to protect them until they fledge around nine weeks later.
A duvet, usually called a comforter or (down-filled) quilt in American English, and a doona in Australian English, is a type of bedding consisting of a soft flat bag filled with either down, feathers, wool, cotton, silk, or a synthetic alternative, and is typically protected with a removable cover, analogous to a pillow and pillow case. The term duvet is mainly British, especially in reference to the bedding; rarely used in US English, it often refers to the cover. Sleepers often use a duvet without a top bed sheet, as the duvet cover can readily be removed and laundered as often as the bottom sheet.
Bedding, also called bedclothes or bed linen, is the materials laid above the mattress of a bed for hygiene, warmth, protection of the mattress, and decorative effect. Bedding is the removable and washable portion of a human sleeping environment. Multiple sets of bedding for each bed are often washed in rotation and/or changed seasonally to improve sleep comfort at varying room temperatures. Most standardized measurements for bedding are rectangular, but there are also some square-shaped sizes, which allows the user to put on bedding without having to consider its lengthwise orientation.
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American robin or Eurasian blackbird, or the elaborately woven hanging nest of the Montezuma oropendola or the village weaver—that is too restrictive a definition. For some species, a nest is simply a shallow depression made in sand; for others, it is the knot-hole left by a broken branch, a burrow dug into the ground, a chamber drilled into a tree, an enormous rotting pile of vegetation and earth, a shelf made of dried saliva or a mud dome with an entrance tunnel. The smallest bird nests are those of some hummingbirds, tiny cups which can be a mere 2 cm (0.8 in) across and 2–3 cm (0.8–1.2 in) high. At the other extreme, some nest mounds built by the dusky scrubfowl measure more than 11 m (36 ft) in diameter and stand nearly 5 m (16 ft) tall. The study of birds' nests is known as caliology.
A feathered dinosaur is any species of dinosaur possessing feathers. That includes all species of birds, and in recent decades evidence has accumulated that many non-avian dinosaur species also possessed feathers in some shape or form. The extent to which feathers or feather-like structures were present in dinosaurs as a whole is a subject of ongoing debate and research.
A comforter, also known as a doona in Australian English, or a continental quilt or duvet in British English, is a type of bedding made of two lengths of fabric or covering sewn together and filled with insulative materials for warmth, traditionally down or feathers, wool or cotton batting, silk, or polyester and other down alternative fibers. Like quilts, comforters are generally laid over a top bed sheet and used to cover the body during sleep. Duvets are another form of quilt, traditionally filled with feathers, though since the late 20th century often made of synthetic fibres or down alternatives.
The eiders are large seaducks in the genus Somateria. The three extant species all breed in the cooler latitudes of the Northern Hemisphere.
Fowling is the hunting of birds by humans, for food (meat), feathers or any other commercially value products, or simply for leisure ("sporting") or collecting trophies. It is comparable to wildfowling, the practice of hunting waterfowls for food or sport. The term is perhaps better known in the Fens of Eastern England than elsewhere, but was certainly not confined to the Fens. The land margins of the north produced down feathers from eider duck for eiderdowns and quilted jackets without necessarily killing the birds. In the Western Isles of Scotland, seabirds were taken from their nests on cliffs. In The Fens and other similar places, a decoy was part of a landowner's well-equipped estate.
The greater adjutant is a member of the stork family, Ciconiidae. Its genus includes the lesser adjutant of Asia and the marabou stork of Africa. Once found widely across southern Asia and mainland southeast Asia, the greater adjutant is now restricted to a much smaller range with only three breeding populations; two in India, one in the north-eastern state of Assam and a smaller one around Bhagalpur; and another breeding population in Cambodia. They disperse widely after the breeding season. This large stork has a massive wedge-shaped bill, a bare head and a distinctive neck pouch. During the day, it soars in thermals along with vultures with whom it shares the habit of scavenging. They feed mainly on carrion and offal; however, they are opportunistic and will sometimes prey on vertebrates. The English name is derived from their stiff "military" gait when walking on the ground. Large numbers once lived in Asia, but they have declined to the point of endangerment. The total population in 2008 was estimated at around a thousand individuals. In the 19th century, they were especially common in the city of Calcutta, where they were referred to as the "Calcutta adjutant" and included in the coat of arms for the city. Known locally as hargila and considered to be unclean birds, they were largely left undisturbed but sometimes hunted for the use of their meat in folk medicine. Valued as scavengers, they were once depicted in the logo of the Calcutta Municipal Corporation.
Fill power is a measure of the loft or "fluffiness" of a down product that is loosely related to the insulating value of the down. The higher the fill power, the more air a certain weight of the down can trap, and thus the more insulating ability the down will have. Fill power is commonly given as a specific volume, expressed in cubic inches per ounce. Common fill power values range from about 300 cubic inches per ounce (170 cm3/g) for feathers to around 900 in3/oz (520 cm3/g) for the highest quality goose down. The rare and relatively expensive down of certain wild waterfowl species such as the Muscovy duck or Common eider can have higher fill powers than goose down. Higher fill powers are associated with a larger percentage of down clusters and a larger average down cluster size.
The following outline is provided as an overview of and topical guide to birds:
Feather development occurs in the epidermal layer of the skin in birds. It is a complicated process involving many steps. Once the feathers are fully developed, there are six different types of feathers: contour, flight, down, filoplumes, semiplumes, and bristle feathers. Feathers were not originally meant for flight. The exact reason why feathers evolved is still unknown. Birds are thought to be descendants of dinosaurs and new technology using melanosomes found in dinosaur fossils has shown that certain dinosaurs that could not fly had feathers.
The following is a glossary of common English language terms used in the description of birds—warm-blooded vertebrates of the class Aves and the only living dinosaurs. Birds, who have feathers and the ability to fly, are toothless, have beakedjaws, lay hard-shelled eggs, and have a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton.
Preening is a maintenance behaviour found in birds that involves the use of the beak to position feathers, interlock feather barbules that have become separated, clean plumage, and keep ectoparasites in check. Feathers contribute significantly to a bird's insulation, waterproofing and aerodynamic flight, and so are vital to its survival. Because of this, birds spend considerable time each day maintaining their feathers, primarily through preening. Several actions make up preening behaviour. Birds fluff up and shake their feathers, which helps to "rezip" feather barbules that have become unhooked. Using their beaks, they gather preen oil from a gland at the base of their tail and distribute this oil through their feathers. They draw each contour feather through their bill, nibbling it from base to tip.
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