Urofaecal glucocorticoid metabolite concentrations in African penguin (Spheniscus demersus) chick populations experiencing different levels of human disturbance

Juan Scheun; Rebecca J Miller; Andre Ganswindt; Lauren J Waller; Lorien Pichegru; Richard B Sherley; Gavin W Maneveldt

doi:10.1093/conphys/coab078

Urofaecal glucocorticoid metabolite concentrations in African penguin (Spheniscus demersus) chick populations experiencing different levels of human disturbance

Conserv Physiol. 2021 Sep 14;9(1):coab078. doi: 10.1093/conphys/coab078. eCollection 2021.

Authors

Juan Scheun^{1

2

3}, Rebecca J Miller⁴, Andre Ganswindt², Lauren J Waller^{4

5}, Lorien Pichegru⁶, Richard B Sherley⁷, Gavin W Maneveldt⁴

Affiliations

¹ Department of Life and Consumer Sciences, University of South Africa, Roodepoort, 1724, South Africa.
² Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0081, South Africa.
³ National Zoological Garden, South African National Biodiversity Institute, Pretoria, 0002, South Africa.
⁴ Department of Biodiversity and Conservation Biology, University of the Western Cape, Bellville, 7535, South Africa.
⁵ Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Table View, 7441, South Africa.
⁶ DST-NRF Centre of Excellence at the Percy FitzPatrick Institute of African Ornithology and Institute for Coastal and Marine Research at the Nelson Mandela University, Port Elizabeth, 6031, South Africa.
⁷ Centre for Ecology and Conservation, University of Exeter, Penry Campus, Penryn, Cornwall, TR10 9FE, UK.

Abstract

Despite the importance of ecotourism in species conservation, little is known about the industry's effects on wildlife. In South Africa, some African penguin (Spheniscus demersus) colonies have become tourist attractions. The species is globally endangered, with population sizes decreasing over the past 40 years. As African penguin chicks are altricial and unable to move away from anthropogenic stressors, it is important to evaluate the effect of tourist activities on baseline glucocorticoid levels as a measure of potential disturbance. Chicks at three study sites within two breeding colonies (Robben Island, Stony Point), with varying levels of exposure to tourism (low/moderate/high) were monitored. Urofaecal samples were collected to determine urofaecal glucocorticoid metabolite (ufGCM) concentrations as an indication of baseline stress physiology. Morphometric measurements were taken to compare body condition between sites. Penguin chicks experiencing low, infrequent human presence had significantly higher mean (± standard deviation) ufGCM levels [1.34 ± 1.70 μg/g dry weight (DW)] compared to chicks experiencing both medium (0.50 ± 0.40 μg/g DW, P = 0.001) and high levels of human presence (0.57 ± 0.47 μg/g DW, P = 0.003). There was no difference in chick body condition across sites. These results suggest that exposure to frequent human activity may induce habituation/desensitization in African penguin chicks. Acute, infrequent human presence was likely an important driver for comparatively higher ufGCM levels in chicks, though several other environmental stressors may also play an important role in driving adrenocortical activity. Nevertheless, as unhabituated chicks experiencing infrequent anthropogenic presence showed significantly higher ufGCM levels, managers and legislation should attempt to minimize all forms of activity around important breeding colonies that are not already exposed to regular tourism. Although the results of this study are crucial for developing enhanced conservation and management protocols, additional research on the long-term effect of anthropogenic activities on African penguin physiology is required.

Keywords: African penguins; body condition; chicks; ecotourism; glucocorticoids; stress physiology.