Widespread extinctions of drought-sensitive butterfly populations in the UK could occur as early as 2050, with extreme droughts expected to become more frequent under various climate change scenarios, reports a paper published online this week in Nature Climate Change. The research shows that the chances of avoiding population collapses can be improved substantially through regional landscape management in combination with reductions in greenhouse gas emissions.
Restoring habitat connections fragmented by human activity, such as agriculture, may reduce population collapse of climate-sensitive butterfly species in response to extreme droughts and may also aid recovery. The effectiveness of land-use changes under future climate change, however, is unclear.
Tom Oliver and colleagues studied long-term butterfly population data from 129 sites of the UK Butterfly Monitoring Scheme to assess the historical responses of 28 species to an extreme drought event in 1995. They identify six drought-sensitive species, including the Cabbage White, Speckled Wood and Large Skipper butterflies, that experienced major population collapses following the 1995 drought and find that reduced habitat fragmentation was associated with faster population recovery. Using projections of different emissions and land-use scenarios the authors find that no level of landscape management alone would prevent widespread local population extinctions by 2100. In addition, for highly fragmented landscapes, under a high-emissions ‘business as usual’ scenario, the authors found that extinctions could begin as early as 2050. Under a low emissions scenario, which would require higher levels of mitigation, reducing habitat fragmentation could improve the probability of population persistence by 50%.
The authors conclude that restoring contiguous habitats, rather than solely maximizing habitat area, in combination with major emissions reductions is required to ensure the survival of drought-sensitive butterflies.