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Birds are a group of warm-blooded vertebrates constituting the class Aves, 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 common ostrich. There are about ten thousand living species, more than half of which are passerine, or "perching" birds. Birds have wings whose development varies according to species; 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 is called ornithology.
The rock dove, rock pigeon, or common pigeon is a member of the bird family Columbidae. In common usage, it is often simply referred to as the "pigeon".
The budgerigar, also known as the common parakeet, shell parakeet or budgie, is a small, long-tailed, seed-eating parrot. Budgies are the only species in the genus Melopsittacus. Naturally, the species is green and yellow with black, scalloped markings on the nape, back, and wings. Budgies are bred in captivity with colouring of blues, whites, yellows, greys, and even with small crests. Juveniles and chicks are monomorphic, while adults are told apart by their cere colouring, and their behaviour.
Breed broiler is any chicken that is bred and raised specifically for meat production. Most commercial broilers reach slaughter weight between four and six weeks of age, although slower growing breeds reach slaughter weight at approximately 14 weeks of age. Typical broilers have white feathers and yellowish skin. Broiler or sometimes broiler-fryer is also used sometimes to refer specifically to younger chickens under 2.0 kilograms, as compared with the larger roasters.
Plumage is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, there can be different colour morphs. The placement of feathers on a bird is not haphazard, but rather emerge in organized, overlapping rows and groups, and these feather tracts are known by standardized names.
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, 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.
Feather-plucking, sometimes termed feather-picking, feather damaging behaviour or pterotillomania, is a maladaptive, behavioural disorder commonly seen in captive birds that chew, bite or pluck their own feathers with their beak, resulting in damage to the feathers and occasionally the skin. It is especially common among parrots, with an estimated 10% of captive parrots exhibiting the disorder. The areas of the body that are mainly pecked or plucked are the more accessible regions such as the neck, chest, flank, inner thigh and ventral wing area. Contour and down feathers are generally identified as the main target, although in some cases, tail and flight feathers are affected. Although feather-plucking shares characteristics with feather pecking commonly seen in commercial poultry, the two behaviours are currently considered to be distinct as in the latter, the birds peck at and pull out the feathers of other individuals.
Marek's disease is a highly contagious viral neoplastic disease in chickens. It is named after József Marek, a Hungarian veterinarian who described it in 1907. Marek's disease is caused by an alphaherpesvirus known as "Marek's disease virus" (MDV) or Gallid alphaherpesvirus 2 (GaHV-2). The disease is characterized by the presence of T cell lymphoma as well as infiltration of nerves and organs by lymphocytes. Viruses related to MDV appear to be benign and can be used as vaccine strains to prevent Marek's disease. For example, the related herpesvirus found in turkeys (HVT), causes no apparent disease in the birds, and continues to be used as a vaccine strain for prevention of Marek's disease.
The domestic pigeon is a pigeon subspecies that was derived from the rock dove. The rock pigeon is the world's oldest domesticated bird. Mesopotamian cuneiform tablets mention the domestication of pigeons more than 5,000 years ago, as do Egyptian hieroglyphics. Research suggests that domestication of pigeons occurred as early as 10,000 years ago.
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 fancier's lung (BFL), also known as bird breeder's lung, is a type of hypersensitivity pneumonitis. It can cause shortness of breath, fever, dry cough, chest pain, anorexia and weight loss, fatigue, and progressive pulmonary fibrosis. It is triggered by exposure to avian proteins present in the dry dust of droppings or feathers of a variety of birds. The lungs become inflamed, with granuloma formation. It mostly affects people who work with birds or own many birds.
Poultry farming is the form of animal husbandry which raises domesticated birds such as chickens, ducks, turkeys and geese to produce meat or eggs for food. Poultry – mostly chickens – are farmed in great numbers. More than 60 billion chickens are killed for consumption annually. Chickens raised for eggs are known as layers, while chickens raised for meat are called broilers.
Parrots, also known as psittacines, are birds of the order Psittaciformes and are found mostly in tropical and subtropical regions. They are made up of four families that contain roughly 410 species in 101 genera. The four families are: Psittaculidae, the Psittacidae, the Cacatuoidea (cockatoos), and the Strigopidae. One-third of all parrot species are threatened by extinction, with higher aggregate extinction risk than any other comparable bird group. Parrots have a generally pantropical distribution with several species inhabiting temperate regions in the Southern Hemisphere, as well. The greatest diversity of parrots is in South America and Australasia.
Feather pecking is a behavioural problem that occurs most frequently amongst domestic hens reared for egg production, although it does occur in other poultry such as pheasants, turkeys, ducks, broiler chickens and is sometimes seen in farmed ostriches. Feather pecking occurs when one bird repeatedly pecks at the feathers of another. The levels of severity may be recognized as mild and severe. Gentle feather pecking is considered to be a normal investigatory behaviour where the feathers of the recipient are hardly disturbed and therefore does not represent a problem. In severe feather pecking, however, the feathers of the recipient are grasped, pulled at and sometimes removed. This is painful for the receiving bird and can lead to trauma of the skin or bleeding, which in turn can lead to cannibalism and death.
Abnormal behavior of birds in captivity has been found to occur among both domesticated and wild birds. Abnormal behavior can be defined in several ways. Statistically, 'abnormal' is when the occurrence, frequency or intensity of a behaviour varies statistically significantly, either more or less, from the normal value. This means that theoretically, almost any behaviour could become 'abnormal' in an individual. Less formally, 'abnormal' includes any activity judged to be outside the normal behaviour pattern for captive birds of that particular class or age. For example, running rather than flying may be a normal behaviour and regularly observed in one species, however, in another species it might be normal but becomes 'abnormal' if it reaches a high frequency, or in another species it is rarely observed and any incidence is considered 'abnormal'. This article does not include 'one-off' behaviours performed by individual birds that might be considered abnormal for that individual, unless these are performed repeatedly by other individuals in the species and are recognised as part of the ethogram of that species.
Pacheco's disease is a highly infectious and acute bird disease caused by a species of herpesvirus, Psittacid alphaherpesvirus 1 (PsHV-1). All psittacine species are susceptible to Pacheco's disease, mainly those in zoological collections and aviaries in any geographic regions. Specifically, Pacheco's disease has a high occurrence rate in Amazon parrots, followed by African grey parrots, parrots, macaws, cockatoos and conures. Due to a very high mortality rate within these susceptible species, concerns are brought to companion bird markets and breeders.
Alopecia in animals is a condition where locations on the body surface that are typically covered in hair, contain areas where hair is absent, and is a condition that can affect other animals besides humans. Alopecia is a condition that can affect wild organisms and captive organisms, however, the condition tends to be more prominent in captive contexts. Development of alopecia in animals is usually the sign of an underlying disease. Some animals may be genetically predisposed to hair loss, while in some it may be caused by hypersensitivity or nutritional factors. These include Moluccan cockatoos, spectacled bears, hedgehogs, raccoons, squirrels, baboons, and chimpanzees since they share 98% of human genes. Others that are selectively bred to have baldness include rabbits, guinea pigs, Syrian hamsters, mice, rats, and cats. Environmental enrichment has been used in some cases to mitigate certain behaviours that cause hair loss, improve alopecia, and address welfare concerns.
Sexual selection in birds concerns how birds have evolved a variety of mating behaviors, with the peacock tail being perhaps the most famous example of sexual selection and the Fisherian runaway. Commonly occurring sexual dimorphisms such as size and color differences are energetically costly attributes that signal competitive breeding situations. Many types of avian sexual selection have been identified; intersexual selection, also known as female choice; and intrasexual competition, where individuals of the more abundant sex compete with each other for the privilege to mate. Sexually selected traits often evolve to become more pronounced in competitive breeding situations until the trait begins to limit the individual's fitness. Conflicts between an individual fitness and signaling adaptations ensure that sexually selected ornaments such as plumage coloration and courtship behavior are “honest” traits. Signals must be costly to ensure that only good-quality individuals can present these exaggerated sexual ornaments and behaviors.
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, characterized by feathers, the ability to fly in all but the approximately 60 extant species of flightless birds, toothless, beakedjaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart and a strong yet lightweight skeleton.
References
- ↑ Pass, D.A. (1989). "The pathology of the avian integument:A review". Avian Pathology. 18 (1): 1–72. doi: 10.1080/03079458908418580 . PMID 18679837.
- ↑ van Zeeland, Y.R.; Schoemaker, N.J. (2014). "Plumage disorders in psittacine birds-part 1: Feather abnormalities". European Journal of Companion Animal Practice. 24 (1): 34–47. hdl:1874/308945.
- ↑ Shivaprasad, H.L. (2002). "Pathology of birds–an overview" (PDF). Proceedings of C.L. Davis Foundation Conference on Gross Morbid Anatomy of Animals. Washington DC: AFIP.
- ↑ Lazic, T; Ackermann, M. R; Drahos, J. M; Stasko, J; Haynes, J. S (2008). "Respiratory herpesvirus infection in two Indian Ringneck parakeets". Journal of Veterinary Diagnostic Investigation. 20 (2): 235–238. doi: 10.1177/104063870802000217 . PMID 18319441.
- ↑ Girling, S.J. (2010). "The welfare of captive birds in the future". In Duncan, Ian J.H.; Hawkins, Penny (eds.). The Welfare of Domestic Fowl and Other Captive Birds. Animal Welfare. Vol. 9. Springer Netherlands. pp. 115–133. doi:10.1007/978-90-481-3650-6_5. ISBN 978-90-481-3650-6.