Islands are rightfully a major focus of conservation investment. Some of the world’s most endangered species have been moved to islands, where they can be more easily monitored and are safe from threats. Invasive species can be completely removed from islands using precision eradication operations, allowing the original inhabitants of islands to flourish once again. Its no small wonder that islands therefore house much more biodiversity than comparable continental areas. However, there is one threat which not even the world’s most isolated islands will be safe from: climate change. In a paper in this month’s issue of Trends in Ecology and Evolution myself and colleagues talk about what the impact of climate change will be on island conservation projects.
The most obvious impact of climate change on islands will be the predicted rise in sea-levels (possibly over one metre in the coming century) and associated loss of island area. Many low-lying islands from which invasive species are currently being eradicated will themselves be eradicated, along with all inhabitants, by that time. However, the threat of climate change is not just to low-lying islands. Even on larger islands, more frequent storms and flooding will cause damage to much larger areas than just sea-level rise alone. Perhaps the most ominous threat is the shift of climatic niche. Endemic and translocated endangered species on islands often have low powers of dispersal, and if their optimal climate shifts elsewhere, they will be unable to follow it themselves, without human assistance.
So what does all this mean for island conservation? We think that in the mid- to long- term (100 years) island conservation managers will have to prioritise which islands are worth investing in for future eradications. Endangered species that are found on, or have been translocated to, small islands (e.g. pest-free islands) may have to be moved to larger islands. In the longer-term, scientists and managers will have to consider how to eradicate or manage pests on very large inhabited islands, or apply their island conservation tools to continental areas, to ensure the longevity of species conservation projects. Luckily, this is already happening in some places, such as the kakapo which were recently transferred to Hauturu (Little Barrier Island) where they have already started breeding, safe from invasive species AND climate change.