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Abnormal behaviour of birds in captivity 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.〔(【引用サイトリンク】title=abnormal behaviour )〕 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. Most abnormal behaviours can be categorised collectively (e.g., eliminative, ingestive, sterotypies), however, many abnormal behaviours fall debatebly into several of these categories and categorisation is therefore not attempted in this article. Abnormal behaviours here are considered to be related to captive housing but may also be due to medical conditions. The article does not include behaviours in birds that are genetically modified to express abnormal behaviour. When housed under captive or commercial conditions, birds often show a range of abnormal behaviours. These are often self-injurious or harmful to other individuals, and include: *Feather pecking〔Huber-Eicher, B. and Sebo, F., (2001). The prevalence of feather pecking and development in commercial flocks of laying hens. Applied Animal Behaviour Science, 74: 223–231〕〔Sherwin, C.M., Richards, G.J and Nicol, C.J., (2010). A comparison of the welfare of layer hens in four housing systems in the UK. British Poultry Science, 51(4): 488-499〕 *Cannibalism〔Savory, J., (2010). Nutrition, feeding and drinking behaviour, and welfare. In ''The Welfare of Domestic Fowl and Other Captive Birds'', I.J.H. Duncan and P. Hawkins (Eds). Springer. pp. 165-188〕〔Savory, C.J., (1995). Feather pecking and cannibalism. World's Poultry Science Journal, 51: 215–219〕〔Rodenburg, T.B., Komen, H., Ellen, E.D., Uitdehaag, K.A., and van Arendonk, J.A.M., (2008). Selection method and early-life history affect behavioural development, feather pecking and cannibalism in laying hens: A review. Applied Animal Behaviour Science, 110: 217-228〕 *Vent pecking〔Sherwin, C.M., (2010). The welfare and ethical assessment of housing for egg production. In ''The Welfare of Domestic Fowl and Other Captive Birds'', I.J.H. Duncan and P. Hawkins (eds), Springer, pp. 237-258〕〔Potzsch, C.J., Lewis, K., Nicol, C.J. and Green, L.E., (2001). A cross-sectional study of the prevalence of vent pecking in laying hens in alternative systems and its associations with feather pecking, management and disease. Applied Animal Behaviour Science, 74: 259-272〕 *Toe pecking〔Leonard, M.L., Horn, A.G. and Fairful, R.W., (1995). Correlates and consequences of allopecking in White Leghorn chickens. Applied Animal Behaviour Science, 43: 17-26〕〔Buitenhuis, A.J., Rodenburg, T.B., Siwek, M., Cornelissen, S.J.B., Nieuwland, M.G.B., Crooijmans, R.P.M.A., Groenen, M.A.M., Koene, P., Bovenhuis, H., and van der Poel, J.J., (2003). Identification of quantitative trait loci for receiving pecks in young and adult laying hens. Poultry Science, 82: 1661-1667〕 *Feather plucking *Stereotypies〔Sargent, T.D. and Keiper, R.R., (1967). Stereotypies in caged canaries. Animal Behaviour, 15: 62-66〕 *Polydipsia〔http://web.archive.org/web/20111004162545/http://www.realmacaw.com/pages/toxi.html〕〔Hardy, W.T. and Westbrook R.F., (1981). Lithium-induced polydipsia in birds: A comparative study and analysis of electrolyte excretion. Physiology and Behavior, 27: 575-583〕 *Sham or "vacuum" dustbathing〔Olsson, I.A.S., Keeling L.J. and Duncan, I.J.H., (2002). Why do hens sham dustbathe when they have litter? Applied Animal Behaviour Science, 76: 53–64〕〔Merrill, R.J.N., Cooper, J.J., Albentosa M.J. and Nicol, C.J., (2006). The preferences of laying hens for perforated Astroturf over conventional wire as a dustbathing substrate in furnished cages. Animal Welfare, 15:173–178〕〔van Liere, D.W., (1992). The significance of fowls' bathing in dust. Animal Welfare, 1: 187–202〕 *Jealous, over-possessive parrot *Chronic egg laying When analyzing the behaviour of birds in captivity, what is considered normal or abnormal behaviour is dependent on the form and frequency that the particular behaviour is expressed in the natural environment.〔Wiepkema, P.R. (1985). Abnormal behavior in farm animals: ethological implications. Netherlands Journal of Zoology, 35, 279-299.〕 Birds raised in pet stores tend to be raised with other birds, however, after being sold and taken to the owner's home, birds in captivity are often housed in isolation and in environments lacking abundant resources or complex stimuli. In the United States, it is estimated that forty million birds are kept caged and improperly cared for.〔“There is no such thing as a cage bird”. People for the Ethical Treatment of Animals. When social interactions amongst birds are absent or inadequate, abnormal social behaviour may develop. For example, a study regarding parrots that had been isolated in cages demonstrated that most birds showing this social deprivation had significant behavioural disturbances, such as aggressive behaviour, feather picking, self-mutilation, restlessness, screaming, apathetic behavior, and stereotypies.〔Lantermann, W. (1993). Social deprivation in Amazon parrots. Animal Behaviour, 38, 511-520.〕 Cannibalism often occurs in large animal husbandry systems, which are usually impoverished environments with a lack of opportunities.〔Hughes, B.O. & Duncan, I.J.H. (1998). The notion of ethological “need,” models of motivation and animal welfare. Animal Behaviour, 36, 1696-1707.〕 In addition, studies of caged canaries have revealed two common stereotypies.〔 These include spot picking, where birds repeatedly touch a particular spot in the environment with the tip of their beak, and route tracing, a pacing behaviour associated with physical restrictions in movement imposed by the cage. The absence of song learning in zebra finches has also been implicated as a behavioural abnormality.〔Slater, P.J,B., Jones, A. & Ten Cate, C. (1993). Can lack of experience delay the end of the sensitive phase for song learning? Netherlands Journal of Zoology, 43, 80-90.〕 In these birds, the social interaction of a young male with his song tutor is important for normal song development. Without the stimulus, the song, which is necessary for mating behavior, will not be learned. Researchers have analyzed ways to alleviate some abnormal behaviours in caged birds. Presenting these birds with novel stimuli e.g. a mirror or plastic birds, and social stimuli, such as a brief view of a bird in another cage, significantly reduced stereotypies.〔Keiper, R.R. (1970). Studies of stereotypy function in the canary (Serinus canarius). Animal Behaviour, 18, 353-357.〕 In addition, it has been suggested that keeping caged birds in pairs or small groups may reduce the development of abnormal behaviours, however, little quantitative evidence has thus far been collected to support this claim.〔 == See also == * Animal psychopathology * Battery cages * Chicken * Comparative psychology * Furnished cages * List of abnormal behaviours in animals * Stereotypy * Stereotypy (non-human) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Abnormal behaviour of birds in captivity」の詳細全文を読む スポンサード リンク
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