BUTTERFLIES: flying into harsher days
BEAUTIFUL and delicate, butterflies have been celebrated for bringing summer colour into our lives since records began but now their annual appearance is threatened as never before.
Despite higher temperatures making Britain more attractive, the relentless destruction of vital habitat is steadily reducing butterfly numbers.
Research has shown that three-quarters of those species which might have expanded northwards due to global warming have instead declined - unable to find enough sites to lay their eggs.
According to the Butterfly Conservation Society, native species which tend to stay in the same area have suffered particularly badly - plummeting 89 per cent in numbers compared to a 50 per cent fall among more mobile species.
The depressing findings are based on an in-depth analysis of 1.6 million butterfly sightings by 10,000 amateur naturalists over a four-year period.
Professor Chris Thomas, who helped co-ordinate the research, said:"Most species of butterflies that reach the northern edge of their geographic ranges in Britain have declined over the last 30 years even though the climate has warmed.
"This is surprising because climate warming is expected to increase the range of habitats these species can inhabit.
"Climatically suitable areas are available for colonisation but most species have failed to exploit them either because they no longer contain suitable breeding habitats, or because breeding habitats are out of reach."
Greatest losers in the downturn are thought to be the Large Tortoiseshell, High Brown Fritillary, Wood White, Pearl-bordered Fritillary, Marsh Fritillary, Large Heath, Silver-studded Blue, Duke of Burgundy, Dingy Skipper, and Small Pearl-bordered Fritillary.
But it is not all bad news and some butterflies are still doing well, especially the Essex Skipper, Brown Argus, Holly Blue, Comma, Purple Hairstreak, Marbled White, White Admiral, Speckled Wood, Ringlet, and Orange-tip.
Among these, the Marbled White is thought to have expanded its range by more than 50 per cent and perhaps this estimate is borne out by the fact that I spotted three within an hour on a walk over the summer.
The survey also showed that there were currently far more butterflies in the south and east of the country than in the north and west.
Among Britain's few remaining butterfly 'hotspots' are the Chilterns, the North and South Downs, the Cotswolds, Salisbury Plain, the Isle of Purbeck, and Dartmoor.
Besides their physical attractiveness, butterflies seem to have exercised a beguiling hold on Man's imagination for centuries and literature is littered with references to them.
Even as far back as the 4th Century BC, writer Chuang Tse is recorded as musing:"I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly dreaming I am a man." Perhaps he had been working too hard.
