Corticosterone is the primary avian stress hormone and has been shown to increase in response to stressors such as low food availability, environmental conditions, as well as human visitation and proximity. Elevated corticosteroid levels have been associated with decreased nest attendance, increased probability of nest abandonment, and general decreases in reproductive success in multiple species of penguin. However, while human disturbance may increase hormonal stress levels in penguins, frequent or consistent exposure may result in decreased stress responses due to habituation. On the Antarctic Peninsula, tourism has increased dramatically over the past 30 years, increasing both the total number of visitors and frequency of visitation at or near penguin colonies. While there is no clear evidence that tourism has affected large-scale population dynamics, physiological responses provide a more fine scale assessment impacts. In this study, we address whether tourist visitation, colony size, or environmental factors are related to hormonal stress responses in gentoo penguins on the Antarctic Peninsula. We examined corticosterone levels in gentoo penguin guano taken from 20 breeding colonies along the Antarctic Peninsula and the South Shetland Islands that represent a wide range of environmental factors, colony size, and tourism visitation level.
Results/Conclusions
We find a large degree of variation in corticosterone levels within and between gentoo penguin breeding colonies. Preliminary results indicate that colonies with high visitation levels and those with small population sizes have increased corticosterone levels compared to large colonies and those with a lower degree of tourist visitation. There is also a significant interaction between visitation level and colony size, indicating that small colonies with heavy visitation may be more susceptible to elevated stress responses. Given increasing tourism in the Antarctic, monitoring stress levels in a non-invasive manner may allow us to identify sites that are more sensitive and may need more careful management, as well to identify those that may have become habituated to human impacts and thus are less likely to be negatively impacted by tourism.