Feather-plucking
Encyclopedia
Feather-plucking, sometimes termed feather-picking, feather damaging behaviour or pterotillomania, is a maladaptive
Adaptive behavior
Adaptive behavior is a type of behavior that is used to adjust to another type of behavior or situation. This is often characterized by a kind of behavior that allows an individual to change an unconstructive or disruptive behavior to something more constructive. These behaviors are most often...

, 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
Pennaceous feather
Pennaceous feathers are also known as contour feathers. This type of feather is present in most modern birds, and has been shown in some species of maniraptoran dinosaurs....

 and down feathers
Down feathers
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,...

 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
Feather pecking
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 and is sometimes seen in farmed ostriches. Feather pecking occurs when one bird repeatedly pecks at the...

 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
Trichotillomania
Trichotillomania, which is classified as an impulse control disorder by DSM-IV, is the compulsive urge to pull out one's own hair leading to noticeable hair loss, distress, and social or functional impairment. It is often chronic and difficult to treat....

, an impulse control disorder
Impulse control disorder
Impulse control disorder is a set of psychiatric disorders including intermittent explosive disorder, kleptomania, pathological gambling, pyromania , and three body-focused repetitive or compulsive behaviors of trichotillomania , onychophagia and dermatillomania...

 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
Comparative psychology
Comparative psychology generally refers to the scientific study of the behavior and mental processes of non-human animals. However, scientists from different disciplines do not always agree on this definition...

 approach to alleviating these problems.

Causes

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.

Early experience

  • Feather-plucking is often attributed to a variety of social causes that may include poor socialisation or absence of parents during the rearing period and because of this, the individual subsequently expressing the disorder fails to learn appropriate preening behaviour. Several studies have focused on the importance of rearing methods (wild-caught, parent-raised, hand-reared).

Isolation

  • In captivity, pet birds are often kept isolated from conspecifics whereas in the wild they would form stable, sometimes large, flocks
    Flock (birds)
    A flock is a group of birds conducting flocking behavior in flight, or while foraging. The term is akin to the herd amongst mammals. The benefits of aggregating in flocks are varied and flocks will form explicitly for specific purposes...

    . These birds may not deal well with a solitary lifestyle. Deprivation of a social or sexual partner may lead to 'separation anxiety', ‘loneliness’, ‘boredom’, sexual ‘frustration’ and/or ‘attention-seeking’ behaviour. These factors may all contribute to feather-plucking, although no empirical studies have been performed to test these ideas.

Barren environment

  • Increasing environmental complexity can reduce feather-plucking, however, other studies have only managed to stabilise existing plumage problems.

Re-directed foraging behaviour

  • Increasing foraging opportunities can markedly reduce feather-plucking. This has many similarities with the redirected foraging behaviour hypothesis proposed for feather pecking in commercial poultry. Birds in captivity are usually given energy-dense, readily available food that is consumed rapidly, whereas in the wild they would have to spend many hours foraging to find this. It is considered that a combination of a barren environment and the 'excess' foraging time available is then spent redirecting foraging to feathers of other individuals. When 18 feather-plucking African Grey parrot
    African Grey Parrot
    The African Grey Parrot , also known as the Grey Parrot, is a medium-sized parrot found in the primary and secondary rainforest of West and Central Africa. Experts regard it as one of the most intelligent birds. They feed primarily on palm nuts, seeds, fruits, leafy matter, but have been observed...

    s (Psittacus erithacus) were provided with food in pipe feeders rather than bowls, their foraging time significantly increased by 73 minutes each day and their plumage improved noticeably within one month.

Stress

  • Feather-plucking has also been interpreted as a coping strategy for negative affective states e.g. stress, loneliness, boredom, induced by inappropriate social or environmental factors. Findings in favour of the stress hypothesis include a study in which distinctive room position affected occurrence of the disorder. Orange-winged Amazon parrots (Amazona amazonica) that were housed in proximity and direct line of sight to the door showed significantly more feather-plucking compared to individuals housed further away from the door, indicating presence of stressors as a causal factor. In addition, parrots that feather-pluck have been found to have higher levels of corticosterone
    Corticosterone
    Corticosterone is a 21-carbon steroid hormone of the corticosteroid type produced in the cortex of the adrenal glands.-Roles:In many species, including amphibians, reptiles, rodents and birds, corticosterone is a main glucocorticoid, involved in regulation of fuel, immune reactions, and stress...

    , a hormone secreted by many animals when they are exposed to chronic stress. It has also been suggested that long day-lengths can cause feather-plucking; presumably this could relate to birds becoming overly tired and therefore stressed.

Medical and Physical Factors

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.

Approximately 50% of parrots exhibiting feather damaging behaviour have been diagnosed as having inflammatory skin disease based on paired skin and feather biopsies. The birds try to relieve itching by grooming their feathers, but this often leads to over-grooming and eventually feather-plucking.

Neurobiological Factors

Little is currently known on brain dysfunction in feather-plucking. However, it may be hypothesized that abnormal brain function is involved, especially in those cases that appear sensitive to treatment with behavioural intervention and/or environmental changes. Psychotropic therapy
Psychoactive drug
A psychoactive drug, psychopharmaceutical, or psychotropic is a chemical substance that crosses the blood–brain barrier and acts primarily upon the central nervous system where it affects brain function, resulting in changes in perception, mood, consciousness, cognition, and behavior...

 for birds has been suggested as treatment for feather-plucking although responses seem variable.

Genetic Factors

In Orange-winged Amazon parrots, a heritability
Heritability
The Heritability of a population is the proportion of observable differences between individuals that is due to genetic differences. Factors including genetics, environment and random chance can all contribute to the variation between individuals in their observable characteristics...

 estimate of 1.14 ± 0.27 was found for feather-plucking, indicating that a genetic basis exists. This study, however, only involved analysis of full siblings and a small number of birds, explaining the heritability value of greater than 1. Quantitative trait loci
Quantitative trait locus
Quantitative traits refer to phenotypes that vary in degree and can be attributed to polygenic effects, i.e., product of two or more genes, and their environment. Quantitative trait loci are stretches of DNA containing or linked to the genes that underlie a quantitative trait...

 (QTL) analysis could provide more insight in possible genetic markers that are involved in feather-plucking.

Treatment

Veterinary
Veterinary medicine
Veterinary Medicine is the branch of science that deals with the prevention, diagnosis and treatment of disease, disorder and injury in non-human animals...

 treatment or an improved and more stimulating environment may help birds suffering from feather-plucking. Organic bitter sprays are sold in pet stores to discourage plucking, especially of newly grown feathers, although this may make general beak-based grooming difficult for the animal.

See also

  • Animal psychopathology
    Animal psychopathology
    Animal psychopathology is the study of mental or behavioral disorders in non-human animals.Historically, there has been an anthropocentric tendency to emphasize the study of animal psychopathologies as models for human mental illnesses...

  • Comparative psychology
    Comparative psychology
    Comparative psychology generally refers to the scientific study of the behavior and mental processes of non-human animals. However, scientists from different disciplines do not always agree on this definition...

  • Stereotypy

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK