An article in the Scottish Daily Record (2019) brought to light the damage that parrots can do to their feathers if they are anxious, stressed or unhappy. In this news story, two zoo-housed macaws with severely damaged feathers and bare skin had been brought together in a new home to try to provide them with new opportunities for positive behaviours – in the hopes of the birds forming a pair bond and rearing a chick. Such “damaged” birds are unfortunately not that uncommon in public and private collections. Feather-plucking behaviour (Figure 1) has a complex aetiology but with compassion and care, expert veterinary advice and sound husbandry knowledge, birds can gradually recover and feathers can grow back.
There are many factors that can trigger the onset of feather-plucking, including the personality of the individual, contact time with owner, enclosure size and style, underlying pathological conditions, rearing experiences, social grouping or social isolation, environmental parameters and restriction to behavioural diversity. Many excellent reviews of the causative factors of feather damaging occur in the literature including Garner et al. (2003), Speer (2014), who discusses the importance of wild ecology to solving behavioural problems in companion birds, and Greenwell and Montrose (2017), who specifically focus on one of the commonest of companion parrots, the African grey parrot (Psittacus erithacus). In cases where a bird is feather plucking due to boredom or a lack of an outlet for normal behaviour patterns, enrichment can be used to encourage a wider behavioural diversity (Figure 2). Whilst enrichment for captive parrots is always to be encouraged and should be provided (Rodríguez-López, 2016), it can be a challenge to completely alter behaviour by providing enrichment alone.
Foraging tasks have been shown to provide an outlet for behaviours that reduce feather plucking in individual birds that are prone to this damaging activity (Figure 3). Research by Lumeij and Hommers (2008) has identified that prolonging foraging times for African grey parrots improves the plumage condition of birds that originally performed chronic feather plucking. These authors provided parrots with a complete pellet diet in a pipe feeder that a bird had to manipulate to get food. These birds were compared to a control group that had pellet given in an open bowl. The parrots that had to extract their diet from the pipe feeder had an increased time spent on foraging and showed a decline in feather-damaging behaviour. These authors note that the feather condition of feather-plucking parrots improved significantly with every extra hour that a bird can spend foraging.
Whilst increasing foraging time seems important to improving parrot welfare and the use of enrichment to do this might sound straightforward, it can be logistically quite tricky to have a big impact on foraging behaviour in this manner. Therefore, other forms of enrichment need to be considered too. Van Zeeland et al. (2013) show that a range of foraging enrichments tested on African grey parrots significantly increased foraging time, but none of them enabled parrots to demonstrate the same number of hours spent foraging that would be performed by free-living birds. The enrichments used were each designed to add complexity to parrot foraging activity, by increasing the spatial distribution of food, increasing the extraction time of food, increasing food processing time or increasing the time needed to search for food. Increasing the extraction time of food and increasing food handling by providing larger food particles are the most effective ways of encouraging parrots to spend more time foraging, with some birds performing 2 to 2.5 times more foraging activity compared to when not enriched. Socialisation, companionship and interaction with parrots in captivity may be just as important as increasing foraging time so that birds do not resort to feather-damaging behaviours to fill their time.
Finally, research by Mellor et al. (2018) shows how by using a behavioural ecology approach to welfare issues, we may better understand their causation and therefore provide more targeted and effective treatment. Targeted environmental enrichment for a specific individual with a specific trigger for feather-damaging behaviour is one such effective treatment. The study evaluated feather damaging and other abnormal repetitive behaviours in birds alongside “Tinbergen’s Four Questions”. The four questions are different levels of analysis of behaviour that describe proximate explanations (causation and development) and ultimate explanations (function and evolution) of an animal’s behaviour (Tinbergen, 1963; Figure 4). By applying these four questions to parrot feather plucking, we can: identify what triggers (both external and internal) control the behaviour’s performance (causation), determine what life history, physiological and experiential influences there are on feather plucking (development), understand whether a coping strategy is the reason for feather plucking (function) and evaluate any heritable traits or genetic predisposition to feather plucking that explain its performance (evolution). As welfare assessments are best performed on an individual level, such an ecological and evolutionary approach can allow practitioners (vets, behaviourists, pet counsellors) to get to the root cause of feather damaging on a case-by-case basis.