By Dr   BSc, BVSc, MRCVS, MACVSc (Avian health)

Feather plucking is one of the most common and yet one of the most complex and at times frustrating conditions that avian veterinarians are presented with.

The first step always in dealing with a behavioural problem such as feather plucking (the other two common problems being screaming and biting) is to make sure that it doesn’t have its roots in an underlying health problem. Feather plucking is a symptom of something else wrong with the bird. The only chance of a successful outcome is to identify and correct what is behind the behaviour. Every feather plucker or feather chewer has a reason for exhibiting the behaviour. Remember, feather plucking is a symptom and not a disease in itself.

And so, what possible health problems are going through an avian vet’s mind when he is initially presented with a feather-plucking parrot for examination and, indeed, what sort of diagnostic tests are at his disposal?

Primary feather follicle irritation
Feather follicles that are itchy or irritated attract the bird’s attention. In its attempt to make itself comfortable, the bird may chew or pick at the feather. Possible causes include an infection associated with mites, bacteria, fungi or a virus. Some species of mite live deep in the feather follicle, wedged between the outer wall of the feather and the lining of the feather follicle. A simple in-aviary test that might indicate the presence of mites is to gently roll a damaged feather out of its follicle. If mites are present, there may be a collar of dry dandruff-like material around the feather. A vet can scrape this material onto a drop of oil on a microscope slide and examine it. Examination can reveal adult mites, nymphs and also eggs. A feather with a healthy follicle is often harder to remove and the section of feather below the skin is clean and shiny. Generalized bacterial infection associated with bacteria such as Staphylococcus can be intensely itchy, while fungi (such as Mucor sp. and Rhizopus sp.) have been associated with itchiness in pigeons as well as parrots. Veterinarians can take skin scrapings and squash feather contents onto slides for microscopic examination. Sometimes, special stains can aid in diagnosis. Feather and skin samples can also be cultured for bacteria and fungus. Both Polyoma virus (associated amongst other things with ‘French Moult’ in budgies) and Circo virus (the agent of PBFD in cockatoos and other birds) can inflame the feather follicle, leading to the growth of abnormal feathers and variable degrees of irritation. These viruses are tested for usually in blood and feather samples where either evidence of the virus itself or antibody to the virus is detected. Interestingly, itchy birds that may appear quite normal sometimes test positive for Circo virus, which means that even though no obvious feather damage is visible, the virus should not be discounted.

The jury is still out on the importance of allergies in itchy birds. What we do know is that we see clinical disease and microscopic lesions associated with allergies in birds that scratch and feather pick. Also, there is a significant difference in the skin testing results between normal and itchy birds. Suggested allergens include Aspergillis sp. (a fungus that grows on organic material such as straw, etc in damp conditions) and sunflower seeds.

Many things found in households that are quite innocuous to humans have been associated with itchy skin in birds. Vapourised cooking oils, alcohol-based sprays and cigarette smoke can all irritate the skin. The low humidity created by central heating is also particularly irritant to rainforest parrots, such as macaws, which have evolved to do well in more humid environments.

Internal disease
Birds don’t have hands but, in the same way that we might rub a sore area to try and make it feel better, birds will pick and chew over an area that is sore. And so, chewing of a localized area may indicate pain or discomfort in that area. A common syndrome here occurs in cockatiels that chew and damage the feathers over their body generally but often particularly over their abdomen. Microscopic examination of these birds’ droppings sometimes reveals a Giardia (a flagellate) infection. Treatment of the Giardia often leads to a resolution of the feather picking. The exact mechanism here is not known but it is thought that either a toxin produced by the Giardia or alternately direct discomfort caused by the organism in the bowel leads to the self-trauma. Chlamydophila infection has also been associated with feather chewing, either due to primary skin changes or internal pain associated with the disease. Liver disease can lead to the deposition of irritant bile salts in the skin. Poorly healed fractures have also been associated with self-trauma. Screening X-rays, blood profiles, together with microscopic examination and cultures of throat swabs and droppings, as well as specific tests for Chlamydophila are all used to gather information.

Poor diets
Poor diets can not only lead to poor quality feathers and dry flaky skin but can also make the skin more vulnerable to secondary infection. Both scenarios result in unhealthy skin that becomes itchy. The diet of any bird with poor quality feathers should always be reviewed. This appears particularly so in Eclectus parrots and it is surprising how many of these birds respond simply to dietary improvement. Vitamin A, in particular, is the nutrient required for healthy skin and mucous membranes. Vitamin A deficiency should always be suspected in birds whose diet is based on dry seed.

Heavy metal poisoning, most commonly associated with inadvertent lead or zinc ingestion through chewing new wire or other metal objects, can lead to behavioural changes (together with other problems) that may manifest as compulsive feather chewing.

Skin lesions
Tumours, feather cysts, xanthomas and non-healing wounds can all draw a bird’s attention to a particular site, leading to feather picking.

Some birds prior to breeding, e.g. some cockatoos, will pluck their feathers to line nesting logs.

Poor feathering and feather loss can occur secondary to some hormonal problems, such as hyperthyroidism (increased function of the thyroid gland) and Addison’s disease (decreased formation of corticosterone by the adrenal gland). Although not a direct cause of feather picking, they may predispose the bird to secondary problems and cause low-grade itchiness.

Diagnosis of a medical cause behind feather picking can be time consuming and at times costly. As veterinarians, we often face the challenge of providing an accurate diagnosis within given financial constraints. Veterinarians endeavor to get to the bottom of the problem without spending client’s money on tests that are unnecessary but at the same time it is important that the bird’s health is not put at risk through an unidentified problem. Usually, however the combination of a concerned bird owner and keen avian vet will identify any medical problem present.

Physical v. psychological
Self-mutilation can be either a physical or psychological problem. If the bird’s clinical examination and diagnostic testing fail to identify a health problem, then through a diagnosis of exclusion a psychological problem becomes more likely.

Parrots are naturally active, intelligent birds that with insufficient input to their sensory pathways simply go ‘stir crazy’. In the same way that a bored lonely working dog confined to a suburban yard will start to exhibit abnormal behaviour, such as barking excessively, being aggressive or destroying objects, parrots will release the same frustrations through mutilating themselves.

In the wild, parrots spend a long time with their parents and in some species (e.g. the galah) crèche groups are formed. This social structure tends to educate the growing birds and reinforce correct behaviour. Birds raised in isolation from a young age are vulnerable to developing a range of aberrant behaviours, including feather plucking. The identification and management of psychological feather plucking is involved and challenging and will be only briefly touched on here.

Psychological self-mutilation usually occurs either as a result of boredom, sexual frustration or anxiety.

Free-flying parrots live in a three-dimensional world full of colour and activity. The parrot owner must mimic this as closely as possible through enriching the bird’s environment. The type of cage, cage location and the provision of interesting food and toys are all relevant here.

Sexual frustration
Many free-roaming parrots travel with their mate in small roving bands. They therefore have a natural need for companionship. In captivity, pet birds will often develop what they perceive as a ‘mate’ relationship with their primary carer. This is obviously inappropriate as no human can fulfill such a role. Fostering such a relationship leads to a situation of unrequited love and simply serves to further the bird’s mental confusion and frustration. The appropriate role for an owner to adopt is that of a friend not a mate. The pet bird should view its primary carer as a benevolent leader. Interestingly, it is thought that the fatty seeds provided in some commercial diets may contain oestrogen precursors and may in some way act as aphrodisiacs, further exacerbating the situation.

Overcrowding, close housing to a non-compatible species excessive noise or disturbance, etc, etc, can all be sources of anxiety. Evaluation needs a careful review of a bird’s management and environment.

No matter what the cause of feather plucking, the earlier it is identified and corrected the better is the chance of a successful outcome. As always, your local avian veterinarian is the best person to consult for advice.