Butterfly effect: rare species make comeback

Britain's butterflies encountered mixed fortunes last year, a study has revealed, with some of the rarest species being helped to recover by the record-breaking warm spring.

The hot, dry weather provided perfect conditions for spring specialists, enabling them to benefit from extended flight periods as they emerged weeks earlier than usual, according to the UK Butterfly Monitoring Scheme.

The threatened duke of Burgundy, probably Britain's most endangered butterfly, rose in numbers by 65 per cent between 2010 and 2011. Other rare spring butterflies prospered – the grizzled skipper recorded a rise of 96 per cent, the pearl-bordered fritillary rose by 103 per cent, and the Lulworth skipper, confined to a small stretch of the Dorset coast, saw an 84 per cent increase following years of decline.

However, other species struggled in the cold summer. The white admiral recorded a 51 per cent fall and the threatened black hairstreak, which recorded a substantial increase between 2009 and 2010, declined again last year.