Behavioural testing to determine differences between coping styles in Grey parrots (Psittacus erithacus erithacus) with and without feather damaging behaviour

In various animal species, a correlation has been found between the individual's response to ‘stressing’ stimuli (coping style) in behaviour tests and the susceptibility to develop behavioural disorders. Based on analogies with feather pecking in laying hens, a similar correlation might be present in parrots with feather damaging behaviour. To investigate whether this correlation is present in parrots, 22 Grey parrots (Psittacus erithacus erithacus) with and without feather damaging behaviour were subjected to (1) a manual restraint test, (2) novel object test and (3) open field test. All tests were performed in a standardized setting, with a one-week interval between the tests. Recordings were made of the parrots’ responses, which were subsequently analysed to determine latency times, intensity, frequency and/or duration of specific behaviours. In addition, blood was collected to assess the birds’ neurophysiologic responses (corticosterone, norepinephrine) during manual restraint. Significant differences were found between the groups of birds with and without feather damaging behaviour with regard to the birds’ reactions in all the behaviour tests. Particularly the response during the open field test was found to correlate well with the presence of feather damaging behaviour: birds with feather damaging behaviour showed higher open field activity indicative of a proactive coping style. Additionally, feather damaging birds displayed proactive behaviour in the novel object test, as expressed by their initial reaction to a novel object. A manual restraint test did not reveal distinct differences in the amount of resistance displayed by the parrots with and without feather damaging behaviour. Struggling frequencies and neurophysiologic responses, however, tended to be different, with a higher number of struggling attempts and a more prominent rise in plasma corticosterone concentrations in birds without feather damaging behaviour. Aforementioned results suggest that parrots with feather damaging behaviour display a proactive coping style, which is similar to the findings in feather pecking laying hens. These findings provide further insight into the aetiology of feather damaging behaviour, and suggest a potential role for behavioural testing in establishing whether a parrot is at risk for developing this behavioural disorder. Further (prospective) studies with larger groups of parrots are, however, needed to confirm a correlation between coping style and the display of feather damaging behaviour throughout the parrot population and to determine whether and which behaviour tests have (the highest) predictive value.