Avian keratin disorder (AKD) is an emerging disease among wild birds in North America characterized by overgrowth and deformities of beaks. Cases were first observed among black-capped chickadees in Alaska in the late 1990s, and it has spread rapidly since then. [1] The cause of AKD is unknown, but may be Poecivirus , a species of virus within the family Picornaviridae [1] that gained ICTV recognition in 2020. [2]
In AKD, accelerated growth of the keratinized outer layer of the beak (the rhamphotheca) [3] causes elongation and crossing of the mandibles of the beak. [1] This is debilitating and often deadly, as it obstructs the birds' ability to feed and preen themselves, with the resulting dirty and matted plumage unable to play its role in thermoregulation. [4]
One potential secondary symptom is the formation of lesions on various other keratinized tissues. Areas affected include the skin, legs, feet, claws, and feathers. Since AKD is not yet well understood, it has not been determined whether these lesions are strictly a secondary symptom or part of a systemic disorder. [4]
A recent study [5] suggests a possible connection between the avian disease Poecivirus and AKD. This study noted that all those affected with AKD also were affected with Poecivirus and suggests Poecivirus may be a possible cause of AKD.
Initially, AKD was reported in only two species of Alaskan bird, the tree sparrow and a single specimen of the white-winged crossbill. [6] [7] While overgrown and crossed beaks have been identified in upwards of 30 species within Alaska alone, many of those have had only a handful of individuals affected. Other than black-capped chickadees, the species most affected are various corvids, nuthatches, and woodpeckers. In addition, surveys of Northwestern and American crow populations have indicated the possibility of regional clusters of AKD: between 2007 and 2008, the prevalence of AKD across Alaska populations of the Northwestern Crow reached nearly 17%, and up to 36% in the Kenai Peninsula. [8] A 2010 study estimated that in the years between 1999 and 2008 up to 6.5% of Alaska Black-capped Chickadees had bill deformities associated with AKD. [4]
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 beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for pecking, grasping, and holding, preening, courtship, and feeding young. The terms beak and rostrum are also used to refer to a similar mouth part in some ornithischians, pterosaurs, cetaceans, dicynodonts, anuran tadpoles, monotremes, sirens, pufferfish, billfishes and cephalopods.
The tits, chickadees, and titmice constitute the Paridae, a large family of small passerine birds which occur mainly in the Northern Hemisphere and Africa. Most were formerly classified in the genus Parus.
The bar-tailed godwit is a large and strongly migratory wader in the family Scolopacidae, which feeds on bristle-worms and shellfish on coastal mudflats and estuaries. It has distinctive red breeding plumage, long legs, and a long upturned bill. Bar-tailed godwits breed on Arctic coasts and tundra from Scandinavia to Alaska, and overwinter on coasts in temperate and tropical regions of Australia and New Zealand. The migration of the subspecies Limosa lapponica baueri across the Pacific Ocean from Alaska to New Zealand is the longest known non-stop flight of any bird, and also the longest journey without pausing to feed by any animal. The round-trip migration for this subspecies is over 29,000 km (18,020 mi).
The fox sparrow is a large New World sparrow. It is the only member of the genus Passerella, although some authors split the species into four.
The black-capped chickadee is a small, nonmigratory, North American passerine bird that lives in deciduous and mixed forests. It is a member of the Paridae family, also known as tits. It has a distinct black cap on its head, a black bib underneath, and white cheeks. It has a white belly, buff sides, and grey wings, back, and tail. The bird is well known for its vocalizations, including its fee-bee call and its chick-a-dee-dee-dee call, from which it derives its name.
The Buteoninae are a subfamily of birds of prey which consists of medium to large, broad-winged species.
The boreal chickadee is a small passerine songbird in the tit family Paridae. It is found in the boreal forests of Alaska, Canada and the northern United States and remains within this range all year. This bird is known for its high pitched trill patterns used in communication with other birds and food storage habits in preparation for winter months.
Keratosis pilaris is a common, autosomal-dominant, genetic condition of the skin's hair follicles characterized by the appearance of possibly itchy, small, gooseflesh-like bumps, with varying degrees of reddening or inflammation. It most often appears on the outer sides of the upper arms, thighs, face, back, and buttocks; KP can also occur on the hands, and tops of legs, sides, or any body part except glabrous (hairless) skin. Often the lesions can appear on the face, which may be mistaken for acne or folliculitis.
The parakeet auklet is a small seabird of the North Pacific. Parakeet Auklets used to be placed on its own in the genus Cyclorrhynchus but recent morphological and genetic evidence suggest it should be placed in the genus Aethia, making them closely related to crested auklets and least auklets. It is associated with the boreal waters of Alaska, Kamchatka and Siberia. It breeds on the cliffs, slopes and boulder fields of offshore islands, generally moving south during the winter.
Cassin's auklet is a small, chunky seabird that ranges widely in the North Pacific. It is the only species placed in the genus Ptychoramphus. It nests in small burrows and because of its presence on well studied islands in British Columbia and off California it is one of the better known auks. It is named for the American ornithologist John Cassin.
The mountain chickadee is a small songbird, a passerine bird in the tit family Paridae.
The keel-billed toucan, also known as sulfur-breasted toucan, keel toucan, or rainbow-billed toucan, is a colorful Latin American member of the toucan family. It is the national bird of Belize. The species is found in tropical jungles from southern Mexico to Ecuador. It is an omnivorous forest bird that feeds on fruits, seeds, insects, invertebrates, lizards, snakes, and small birds and their eggs.
The chestnut-backed chickadee is a small passerine bird in the tit family, Paridae, native to western North America.
Psittacine beak and feather disease (PBFD) is a viral disease affecting all Old World and New World parrots. The causative virus—beak and feather disease virus (BFDV)—belongs to the taxonomic genus Circovirus, family Circoviridae. It attacks the feather follicles and the beak and claw matrices of the bird, causing progressive feather, claw and beak malformation and necrosis. In later stages of the disease, feather shaft constriction occurs, hampering development until eventually all feather growth stops. It occurs in an acutely fatal form and a chronic form.
Bird anatomy, or the physiological structure of birds' bodies, shows many unique adaptations, mostly aiding flight. Birds have a light skeletal system and light but powerful musculature which, along with circulatory and respiratory systems capable of very high metabolic rates and oxygen supply, permit the bird to fly. The development of a beak has led to evolution of a specially adapted digestive system.
A panzootic is an epizootic that spreads across a large region, or even worldwide. The equivalent in human populations is called a pandemic.
The masked crimson tanager is a species of bird in the family Thraupidae. It is found in Bolivia, Brazil, Colombia, Ecuador, and Peru. Its natural habitats are subtropical or tropical swamps and subtropical or tropical moist shrubland.
AKD or akd may refer to:
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.
