With an estimated prevalence of 10-15%, feather damaging behaviour (FDB) is a common behavioural disorder in captive parrots (in particular Grey parrots, the species studied in this thesis) that may have aesthetic, medical and welfare consequences and often results in relinquishment or euthanasia. Little evidence-based information, however, is available on the aetiology, associated risk factors, preventive and/or therapeutic interventions. A review of the literature identified many similarities between FDB in parrots, feather pecking in laying hens and trichotillomania in humans and suggested new focus areas for studies into FDB in parrots, which concern both environmental (extrinsic) and animal-bound (intrinsic) factors. First, however, a new feather scoring system was developed for evaluating changes in plumage condition. When compared to an existent feather scoring system, this novel system resulted in higher absolute and relative intra- and inter-observer reliabilities, rendering it useful for monitoring changes in plumage (and FDB) in response to preventive or therapeutic interventions. Environmental enrichment may be an effective tool to reduce FDB. In particular the provision of foraging enrichment is important, as indicated by the presence of contrafreeloading [CFL] in Grey parrots, which demonstrates that parrots are motivated to work for food in presence of free food. The effect of currently available foraging enrichments, however, is too limited to increase foraging times to levels comparable to that of wild conspecifics. These findings emphasize the necessity to develop more effective foraging strategies, but gaining insight into the value of other types of enrichment may be just as important. For this purpose, a closed-economy, two-chamber set-up was designed, which appears promising to establish parrots’ motivation to gain access to different enrichments, thereby allowing for specific recommendations to be made regarding the captive parrot’s living environment. Interestingly, feather damaging parrots were less motivated to work for food compared to healthy individuals, suggesting alterations in their behaviour and ‘needs’. This finding stresses the importance for studies into potential intrinsic factors involved in FDB. Behavioural tests demonstrated that feather damaging parrots display a proactive coping style, suggesting that temperamental traits may play a role in the development of FDB. In addition, neurotransmitters such as serotonin may be involved. To obtain evidence supporting its role, the efficacy of selective serotonin reuptake inhibitors (e.g. paroxetine) in the treatment of FDB may be studied. A pharmacokinetic study helped to establish a dosing regimen (twice daily 4 mg/kg paroxetine HCl dissolved in water, orally) which may subsequently be used in double-blinded, randomised, placebo-controlled clinical trials. The current studies focused on the behaviour and needs of (feather damaging) Grey parrots and laid a basis to further elucidate the role of various intrinsic and extrinsic factors in the onset and maintenance of FDB, and evaluate new therapeutic and preventive interventions that are currently under development.
Full-text at Igitur Archive, Utrecht University
June 25, 2013