Abstract
Simple SummaryThe African Grey Parrot is a very popular bird commonly found in zoological collections. However, captivity can prevent it from meeting its natural needs and so become an ongoing stressor, leading sometimes to clinical and/or behavioral disorders. Non-invasive forms of stress assessment are of definite interest for monitoring welfare in captive bird populations. One notable stress outcome is the excretion of glucocorticoid metabolites (from the stress hormone corticosterone) in droppings. The aim of this study was to carefully assess methods of glucocorticoid metabolites extraction and measurement in droppings from African Grey Parrots. Several extraction and enzyme immunoassays procedures were tested, based on the evaluation of analytical quality parameters and biological relevance. The best procedure was found to be a combination of a 60% methanol extraction with the use of a commercial corticosterone enzyme immunoassay. To determine whether this method was suitable for assessing different stress levels, a significant correlation with another reliable stress marker in birds, the Heterophil: Lymphocyte Ratio, was evidenced. This method can thus be used to evaluate stress in African Gray Parrots in a non-invasive way and help to monitor their welfare in zoo populations for instance.Despite being undomesticated, African Grey Parrots (Psittacus erithacus) are commonly found in captivity, in zoos or as pets. Captivity can be an ongoing stressor. Non-invasive glucocorticoid metabolites (GCM) measurements from bird droppings are of interest for assessing stress but require careful evaluation in each newly studied species. This study describes the assessment of such methods for Psittacus erithacus to provide tools for evaluating stress and monitoring welfare. We evaluated 12 method combinations of GCM extraction and enzyme immunoassay (EIA) from a pool of African Grey Parrot droppings, through the validation of several analytical parameters. Then, Heterophil: Lymphocyte Ratios (HLR), another reliable stress marker, were determined and correlated to individual dropping GCM concentrations for 29 birds to determine whether the method is biologically relevant. We found that the best procedure to measure GCM in African Grey Parrot droppings is a combination of 60% methanol extraction measured using a Corticosterone EIA kit (Cayman Chemical Company) from fresh or dry droppings. The establishment of a significant correlation (Pearson coefficient correlation = 0.48; p = 0.0082) between HLR and GCM in the studied population confirmed the method biological relevance. This method can thus be applied to assess stress in Psittacus erithacus and support welfare monitoring in zoo populations.
Highlights
The African Grey Parrot (Psittacus erithacus) belongs to the order Psittaciformes, which includes very different species (~356) from different biotopes with very specific needs [1]
African Grey Parrots are increasingly common in zoological collections [11], but their intelligent and social nature and sensitivity combined with the difficulty of meeting their natural needs in captivity make them vulnerable to stress [7,12,13]
The dropping samples in our study were all above the critical mass limit described by Millspaugh and Washburn [26], i.e.,
Summary
The African Grey Parrot (Psittacus erithacus) belongs to the order Psittaciformes, which includes very different species (~356) from different biotopes with very specific needs [1]. The major threat to the African Grey Parrot species arises from its status as a very popular avian pet [3], prized for its longevity, intelligence, and unparalleled ability to imitate human speech and other sounds [4,5]. They are not truly domesticated animals, because most are directly removed from the wild, due to the remaining illegal trade, or bred for only one or two generations [6,7]. Captivity may be an ongoing stressor which can threaten the welfare of these birds [6,7,13,14]
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