Measures of Adrenal and Gonadal Hormones in Relation to Biological and Management Factors among Captive Red Pandas in Indian Zoos

SIMPLE SUMMARY: Red pandas are a threatened species, and zoos worldwide are working to conserve the species through international captive breeding programs. However, information on the physiology of captive red pandas is limited, which is hampering efforts to increase reproductive success and meet captive breeding goals. This study measured concentrations of fecal glucocorticoid (fGCM), progestagen (fPM), and androgen (fAM) metabolites in relation to environmental and biological factors among captive red pandas housed at three Indian zoos. Data revealed that fGCM concentrations were influenced by social time together (−), visitor numbers (+), number of nests (+), frequency of feedings (−), log density (−), and enclosure area (+). The fPM results suggested that enclosure area negatively affected concentrations in females. By contrast, fAM in males was not affected by these factors. This study suggests that employing more frequent feeding schedules and controlling the number of visitors may have positive effects on the welfare of red pandas, while higher fGCM and lower fPM in larger enclosures might be related to the limited enrichment and hiding spaces in those areas. ABSTRACT: Animals in human care are affected by stressors that can ultimately reduce fitness. When reproduction is affected, endangered species conservation programs can be severely compromised. Thus, understanding factors related to stress and reproduction, and related hormones, is important to ensure captive breeding success. Red pandas (Ailurus fulgens) are endangered, and populations in the wild are threatened with extinction. A global captive breeding program has been launched to conserve the species with the goal of reintroduction. However, there is little information on how stressors impact physiological aspects of the species. This study measured fecal glucocorticoid (fGCM), progestagen (fPM), and androgen (fAM) metabolite concentrations in 12 female and 8 male red pandas at 3 zoos in India to determine predictors of adrenal and gonadal steroid activity, and the influence of fGCM on reproduction. Based on the generalized linear mixed model (GLMM), fGCM concentrations were positively correlated with the number of visitors, number of nests and enclosure areas, and negatively related to frequency of feedings, log density, and social time, while fPM concentrations were negatively associated with enclosure areas. A confounder for enclosure areas and number of nests was the fact that these spaces were relatively barren, with limited hiding spaces, compared to the smaller enclosures. By contrast, no significant relationships were found for fAM, perhaps due to the smaller sample size. A negative relationship between fGCM and fPM was observed, indicating increasing adrenal hormones may decrease reproductive function among female red pandas. Results suggest that zoo management should consider increasing feeding frequency, providing larger enclosures with more enrichment and more nests in larger spaces, and regulating visitor numbers to support good welfare and potentially improve reproductive fitness of red pandas in captivity.