Image copyright Iain H Leach Image caption The High Brown Fritillary is found only at 30 sites in the UK

The warm start to 2014 boosted the number of some butterflies, including the critically endangered High Brown Fritillary, a survey has found.

More than half of 56 species studied saw their numbers rise compared with the previous year, according to the UK Butterfly Monitoring Scheme.

The High Brown Fritillary also benefited from schemes to restore habitat, said Butterfly Conservation.

But others - such as the cabbage white - struggled in high summer.

The High Brown Fritillary is one of only two butterflies classed as critically endangered in the UK so it is fantastic news that numbers are at their highest level for more than a decade Dr Tom Brereton, Butterfly Conservation

Cooler conditions later in the year meant the butterfly season peaked early, the study by Butterfly Conservation and the Centre for Ecology and Hydrology found.

Known for its black and orange wings and swift flight, the High Brown Fritillary was once widespread across England and Wales but numbers have declined massively since the 1970s.

It is now down to a single colony in Wales and only two remaining strongholds in England, around Morecambe Bay and on Dartmoor.

The survey found the butterfly recorded its best year for a decade.

This was due to both the warm, wet spring, which was good for emerging caterpillars, and wildlife-friendly farming schemes to restore the woodland and moorland slopes where it breeds, said Butterfly Conservation.

Its head of monitoring, Dr Tom Brereton, said the butterfly was on the road to recovery but there was still a long way to go.

Image copyright Tony Cox Image caption The small white butterfly declined

Image copyright Steve Maskell Image caption The rare Lulworth skipper fared well

"The High Brown Fritillary is one of only two butterflies classed as critically endangered in the UK so it is fantastic news that numbers are at their highest level for more than a decade," he said.

"A huge amount of work coordinated by Butterfly Conservation has been put into conserving this butterfly in recent years, especially through wildlife-friendly farming schemes, so the results will come as a welcome boost to all involved."

Mixed picture

The warmer than average spring and early summer in 2014 also helped other species of butterfly which emerge early in the year, including the Marbled White, Ringlet and Brimstone, which all had their best year since the survey began in 1976.

The survey recorded a 26% increase in numbers compared to 2013 for the threatened Duke of Burgundy, while the rare Lulworth skipper also fared well.

But some butterflies that emerge in high summer struggled in the colder August weather, including the Chalk Hill Blue, Adonis Blue and the two "cabbage white" species.

Overall, 32 of the 56 species studied by the monitoring scheme saw their numbers rise compared to 2013, one showed no change, and 23 species saw numbers fall.

Around 100,000 more butterflies were counted across the UK in 2014 than in 2013.

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