Angel wing, also known as airplane wing, slipped wing, crooked wing, and drooped wing, is a syndrome that affects primarily aquatic birds, such as

geese A goose ( : geese) is a bird of any of several waterfowl species in the family Anatidae. This group comprises the genera '' Anser'' (the grey geese and white geese) and ''Branta'' (the black geese). Some other birds, mostly related to the she ...

and

duck Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form ...

s, in which the last joint of the wing is twisted with the wing feathers pointing out laterally, instead of lying against the body. Males develop it more frequently than females. It has also been reported in

goshawk Goshawk may refer to several species of birds of prey, mainly in the genus ''Accipiter'': * Northern goshawk, ''Accipiter gentilis'', often referred to simply as the goshawk, since it is the only goshawk found in much of its range (in Europe and N ...

bustard Bustards, including floricans and korhaans, are large, terrestrial birds living mainly in dry grassland areas and on the steppes of the Old World. They range in length from . They make up the family Otididae (, formerly known as Otidae). Bust ...

chicks, and

psittacine Psittacinae is a subfamily of Afrotropical or Old World parrots, native to sub-Saharan Africa, which include twelve species and two extant genera. Among the species is the iconic grey parrot. The ''Poicephalus'' are usually green birds with dif ...

birds (

budgerigar The budgerigar ( ; ''Melopsittacus undulatus''), also known as the common parakeet or shell parakeet, is a small, long-tailed, seed-eating parrot usually nicknamed the budgie ( ), or in American English, the parakeet. Budgies are the only spe ...

macaw Macaws are a group of New World parrots that are long-tailed and often colorful. They are popular in aviculture or as companion parrots, although there are conservation concerns about several species in the wild. Biology Of the many differ ...

s, and

conure Conures are a diverse, loosely defined group of small to medium-sized parrots. They belong to several genera within a long-tailed group of the New World parrot subfamily Arinae. The term "conure" is used primarily in bird keeping, though it has ...

s).

Description

The syndrome is acquired in young birds. Due to a high-

calorie The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of o ...

diet, especially one high in

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

s and/or low in

vitamin D Vitamin D is a group of Lipophilicity, fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group ar ...

vitamin E Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. Vitamin E deficiency, which is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vi ...

, and

manganese Manganese is a chemical element with the Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of ...

, one or both

carpus In human anatomy, the wrist is variously defined as (1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; "The wrist contains eight bones, roughly aligned in two rows, known as the carpal ...

(wrist) joints are delayed in their development relative to the rest of the wing; for reasons unknown, if only one wing is affected, it is usually the left one. The result is a wrist which is twisted outwards and unable to perform its usual function. Angel wing symptoms include stripped

remiges Flight feathers (''Pennae volatus'') are 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 (), singular remex (), while those on the tail ...

(flight

feathers 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 a premier ...

) in the wrist area, or remiges protruding from wings at odd angles. In extreme cases, the stripped feathers may resemble sickly blue straws protruding from wings. In adult birds, the disease is incurable and usually leads to an early death, as affected birds are rendered effectively or totally flightless. In young birds, wrapping the wing and binding it against the bird's flank, together with feeding the bird a more nutritionally balanced diet, can reverse the damage. The theoretical causes of angel wing are genetics, the excessive intake of carbohydrates and proteins, together with insufficient intake of vitamin E, low dietary calcium and manganese deficiency. However, scientific studies have not proven any link between bread and angel wing, and some academics refute the connection.

References

{{Commons category, Angel wing (waterfowl) Bird diseases