Feather-plucking

Feather-plucking, sometimes termed feather-picking, feather damaging behaviour or pterotillomania, is a maladaptive, behavioural disorder commonly seen in captive birds which 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 Psittaciformes, 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.

Feather-plucking has characteristics that are similar to trichotillomania, an impulse control disorder in humans, and hair-pulling which has been reported in mice, guinea pigs, rabbits, sheep and muskox, dogs and cats, leading to suggestions for a comparative psychology approach to alleviating these problems.

Feather-plucking is generally regarded as a multifactorial disorder, although three main aspects of bird keeping may be related to the problem: (1) cage size often restricts the bird’s movements; (2) cage design and barrenness of the environment often do not provide sufficient behavioural opportunities to meet the bird's sensitivity, intelligence and behavioural needs; and (3) solitary housing, which fails to meet the high social needs of the bird.

Many medical causes underlying the development of feather-plucking have been proposed including allergies (contact/inhalation/food), endoparasites, ectoparasites, skin irritation (e.g. by toxic substances, low humidity levels), skin desiccation, hypothyroidism, obesity, pain, reproductive disease, systemic illness (in particular liver and renal disease), hypocalcaemia, psittacine beak and feather disease (PBFD), proventricular dilatation syndrome, colic, giardiasis, psittacosis, airsacculitis, heavy metal toxicosis, bacterial or fungal folliculitis, genetic feather abnormalities, nutritional deficiencies (in particular vitamin A) and/or dietary imbalances, and neoplasia. For many of the above-mentioned factors, a causative relationship or correlation has not been established and may therefore merely be the result of coincidental findings.

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