Abstract
Invasive species present a major conservation threat globally and nowhere are their affects more pronounced than in island ecosystems. Determining how native island populations respond demographically to invasive species can provide information to mitigate the negative effects of invasive species. Using 20 years of mark-recapture data from three sympatric species of albatrosses (black-browed Thalassarche melanophris, grey-headed T. chrysostoma, and light-mantled albatrosses Phoebetria palpebrata), we quantified the influence of invasive European rabbits Oryctolagus cuniculus and extreme weather patterns on breeding probability and success. Temporal variability in rabbit density explained 33–76% of the variability in breeding probability for all three species, with severe decreases in breeding probability observed after a lag period following highest rabbit numbers. For black-browed albatrosses, the combination of extreme rainfall and high rabbit density explained 33% of total trait variability and dramatically reduced breeding success. We showed that invasive rabbits and extreme weather events reduce reproductive output in albatrosses and that eliminating rabbits had a positive effect on albatross reproduction. This illustrates how active animal management at a local breeding site can result in positive population outcomes even for wide ranging animals like albatrosses where influencing vital rates during their at-sea migrations is more challenging.
Highlights
Invasive species present a major conservation threat globally and nowhere are their affects more pronounced than in island ecosystems
The influence of invasive species on island ecosystems already experiencing pressure from global climate change may result in trophic imbalances amongst native communities, and reduced species resilience in the face of multiple threats[4]
Light-mantled albatrosses, which breed island-wide, showed decreases six months after high rabbit density, whereas black-browed and grey-headed albatrosses, which breed at the southern end of the island, showed a four and a half-year lag between high rabbit density and low breeding probability
Summary
Invasive species present a major conservation threat globally and nowhere are their affects more pronounced than in island ecosystems. We showed that invasive rabbits and extreme weather events reduce reproductive output in albatrosses and that eliminating rabbits had a positive effect on albatross reproduction This illustrates how active animal management at a local breeding site can result in positive population outcomes even for wide ranging animals like albatrosses where influencing vital rates during their at-sea migrations is more challenging. Given the frequency and severity of extreme weather events, such as heat waves and precipitation, are predicted to increase as a result of global climate change[5], their effects on island ecosystem structure and function are likely to be exacerbated[6]. There are profound demographic responses of burrowing seabirds to high rabbit density, including reduced reproductive output through increased competition for burrow-nesting habitat[17,18]. For albatrosses which have low immigration rates and in most cases severely diminished populations due to widescale declines in adult survival driven by interactions with commercial fishing operations[23], reproductive rates can have greater influence on population growth rate and should be assessed
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