Cold winter boosts butterfly numbers
11 February 2011
Some of Britain's rarest butterflies are increasing in numbers and may have a better long-term chance of survival following this winter's prolonged cold snap.
In Scotland, the pearl bordered fritillary (Boloria euphrosyne), has been found alive and well in several previously undiscovered colonies in the Scottish Highlands to the west of Dingwall. The pearl bordered fritillary is one of the most rapidly declining butterflies in Britain and Ireland, with populations falling by more than 60% over the 20 years to 2004, when the last population survey was done. In Scotland the situation is less severe, although numbers have still dropped by a third.
Graham Findlay, of the Forestry Commission, said the cold winter has reduced incidence of disease and viral attacks on caterpillars, allowing them to hibernate in safety.
'It's a fantastic find,' he said. 'We counted more than 20 individuals on the wing in one small, open patch.'
Meanwhile on Exmoor in Devon, two rare butterflies, the heath fritillary and the marsh fritillary, have been seen in increasing numbers, while the National Trust has recorded the highest-ever populations of large blue butterflies at Collard Hill, their open-access site in Somerset. Matthew Oates, Nature Conservation Advisor to the Trust, said the cold winters have allowed wild creatures to hibernate properly.
'For the first time in a generation we have experienced a traditional year of weather and our wildlife has mostly responded favourably,' he said.