Avian scavengers as indicators of recovery of an island biota

Abstract

Ecosystem processes are changing worldwide, especially with the impacts of invasive species being exacerbated by climate change. This is particularly obvious in the Southern Ocean where a warmer and dryer environment allows the proliferation of species once limited by the cold climate. South African Special Nature Reserve, Marion Island is no exception. A recent proliferation of invasive House Mouse Mus musculus attacks on endangered breeding seabirds suggests a profound alteration of the natural ecosystem. This has led to the planned eradication of mice at Marion Island. The only viable approach is likely to result in the poisoning of some non-target fauna, especially three data deficient species of avian scavengers: Black-faced Sheathbill Chionis minor, Kelp Gull Larus dominicanus and Brown Skua Stercorarius antarcticus. By focusing on these three species and some of their prey, we intend first to fill identified scientific gaps that are crucial for best planning of the eradication and development of appropriate mitigation measures. Second, we propose to use the three scavengers as indicators of recovery of the terrestrial ecosystem post-eradication by establishing baselines for the scavenger guild and their prey against which the impact of a successful mouse eradication can be measured in years to come. By using avian scavengers as indicators of terrestrial ecosystem functioning, we will be able to infer the recovery of lower trophic levels and, through this holistic approach, how the whole island ecosystem recovers. Over the three years of the project we aim at filling gaps in genetics, phenology, demography, trophic ecology and disease ecology of these three species. Science of a high standard will be completed by an international team, while data will be swiftly shared with the eradication team and other stakeholders to ensure the application of the results. We envision our project to be at the forefront of research driven conservation in the Southern Ocean.