Butterfly behaviour linked to climate change

Butterflies basking in the relatively warm South of Britain are likely to be more liberal in their choice of where to live than their cousins in the cooler and wetter North, according to new findings published this week.

The research, carried out by scientists from the Centre for Ecology & Hydrology, Butterfly Conservation and the University of York, has important implications for efforts to conserve butterfly species under changing climates, particularly where habitat restoration or conservation is planned.

Scientists already know that the location of food plants can limit where butterflies are found, but the new study is the first time that researchers have shown how the climate of an area can affect the number of habitat types or 'environmental space', such as grassland, woodland or heathland, that species are able to use for growth.

The study concluded that species' niches - the range of habitat types that butterflies choose to live in - are broader in warmer southern British locations, where butterflies are most abundant, than in the cooler north.

Lead author Dr Tom Oliver from the Centre for Ecology & Hydrology said, "If these trends hold over time as well as space, then climate warming in Britain may benefit many butterfly species by allowing them to use a wider range of habitats.

"We must be wary though, as an increased frequency of climatic extremes, such as unseasonal cold snaps, could severely reduce butterfly populations and possibly restrict them to fewer habitat types".

The research team analysed data for 41 butterfly species. In areas with cold winters and high rainfall, the harsh climates can cause many habitat types to be unsuitable, restricting butterflies to only their favourite habitats. In contrast, in warmer locations life is easier for 'thermophilic', or warmth loving, insects such as butterflies and they are able to spread across the landscape.

The researchers also concluded that as the British climate changes over time butterflies are likely to modify their habitat requirements. They predict that species such as Small Coppers and Gatekeepers may become more frequent visitors to our parks and urban gardens.

Co-author Tom Brereton, Head of Monitoring at Butterfly Conservation said: "The results indicate that more wide-ranging efforts are needed in order to conserve butterflies in the face of new threats. It is vital we keep large areas of well-managed habitat in the landscape to allow species to adapt and survive."