Good habitat is key to drought survival,

Preventing habitat fragmentation could help butterflies survive severe drought in the future, a study has revealed.

The analysis, published today in the journal Ecography, found that the recovery of butterfly populations to extreme drought events is affected by the overall area and amount of fragmentation of key habitats in the landscape.

Co-author Dr Tom Brereton from Butterfly Conservation explained: "Our results suggest that landscape-scale conservation projects are vital in helping species to recover from extreme events expected under climate change.

"But, if we do nothing, the high levels of habitat fragmentation will mean species are more susceptible".

The UK has suffered several severe droughts over the last few decades. The intense summer drought of 1995 led to notable declines in insect species associated with cooler and wetter microclimates.

The frequency of droughts is expected to increase in the coming years as a result of climate change so scientists are interested in how to make populations more resistant to and more able to recover from extreme climate events.

Lead author Dr Tom Oliver from the NERC Centre for Ecology & Hydrology said: "Most ecological climate change studies focus on species' responses to gradual temperature rise, but it may be that extreme weather will actually have the greatest impact on our wildlife.

"We have provided the first evidence that species responses to extreme events may be affected by the habitat structure in the wider countryside; for example in the total area and fragmentation of woodland patches". 

The researchers studied the Ringlet - a grass-feeding butterfly commonly found close to woodland edges and known to be susceptible to drought effects.

They found that following the 1995 drought, Ringlet populations crashed most severely in drier regions but those living in more connected patches of woodland habitat were less susceptible to drought and able to recover from its effects more quickly.

Although many populations did show some recovery following the 1995-6 population crashes, the long-term situation of the species in some parts of the UK is worrying.

Researchers found that 18% of Ringlet populations continued to decline in the subsequent three years. The majority of populations showed some positive recovery but only 33% of populations showed complete recovery to pre-drought population levels.

Dr David Roy from the NERC Centre for Ecology & Hydrology added: "The delayed recovery of butterfly populations is worrying given that severe summer droughts are expected to become common in some areas of the UK, for example, South East England.

"If populations don't recover by the time the next drought hits, they may face gradual erosion until local extinction."

The study was led by Dr Tom Oliver from the NERC Centre for Ecology & Hydrology (CEH) in collaboration with colleagues from CEH and Butterfly Conservation and used data from 79 UK Butterfly Monitoring Scheme sites collected between 1990 and 1999, a period which spanned a severe drought event in 1995.