Fecal glucocorticoid analysis as a health monitoring tool for endangered African penguins (Spheniscus demersus)
Publication Type: |
Journal Article |
Year of Publication: |
2022 |
Authors: |
Maureen V Driscoll, Allison D Tuttle, Tracy A Romano |
Publication/Journal: |
General and Comparative Endocrinology |
Keywords: |
african penguin, breeding, corticosterone, fecal glucocorticoid metabolites, molt, noninvasive |
ISBN: |
0016-6480 |
Abstract:
African penguins (Spheniscus demersus) are an endangered species, with approximately 70,000 mature adults remaining in the wild. Population loss is linked to a combination of environmental and anthropogenic stressors. The aim of the study was to validate a commercially available enzyme immunoassay (EIA) to assess adrenal activity and measure the response to stressors in the feces of African penguins. Fecal samples (n=609) were collected from 12 African penguins housed at Mystic Aquarium throughout their natural lifecycle, including breeding and molt, where measurable changes in fecal glucocorticoid metabolite (FGM) levels are predicted to occur. Fecal samples collected post-veterinary exam were used for biological validation. Longitudinal analysis shows a significant difference (p=<0.0001) between the average FGM levels during baseline and breeding season, 33.97±1.30 ng/g and 50.21±3.18 ng/g, respectively. Females displayed significantly higher FGM levels than males during both baseline (p=0.0386; females = 38.80±2.19 ng/g; males = 29.34±1.37 ng/g) and breeding periods (p=0.0175; females = 57.53±4.84 ng/g; males = 42.69±3.95 ng/g). Average FGM levels decreased significantly over the three-week molting period, from 85.40±20.35 ng/g at week one to 20.23±5.30 ng/g at week three. A seasonal difference in FGM levels was observed in both male and female fecal samples, with Fall having the highest average FGM levels, 54.38±3.64 ng/g, and Summer the lowest, 30.87±2.21 ng/g. General linear mixed model analysis determined that lifecycle (females) and visitor presence (males) were the two factors which best explained the variation in FGM levels observed, however neither factor was found to be significant. These results show FGM analysis can detect physiologically meaningful changes in endocrine activity in African penguins and can be used to monitor health for penguins in aquaria and in the wild, thus contributing to conservation efforts for the survival of the species.