New data shows that some of Britain's most threatened butterflies showed encouraging signs of recovery last year.
Butterfly Conservation says that while overall butterfly numbers continue to decline, the indications are that recent conservation efforts have had a positive effect on some of the most threatened species.
Last year's weather also played a vital role in boosting some butterfly species.
The biggest winner of 2010 was the Wood White which bounced back with a six-fold increase over 2009, having suffered a massive 96 per cent decline since the 1970s.
Another winner was the Marsh Fritillary which more than doubled its numbers in 2010 compared with 2009, confirming that its overall trend is now upwards, reversing a serious long-term decline that has been going on since the 1950s.
It is not all good news. The data shows it was the worst year on record for two species. One of the UK's commonest butterflies, the Meadow Brown had its worst ever year, with numbers down by a fifth compared with 2009. One of our rarest butterflies the Lulworth Skipper also had its worst year - its numbers are down a frightening 93 per cent over the last decade. The reasons for these losses are still not fully understood and are the subject of current research.
It was also a bad year for migrants - numbers dropped by 90 per cent and there was no repeat of the Painted Lady immigration, which was a spectacular feature of the 2009 season.
The new data comes from the UK Butterfly Monitoring Scheme, the largest and longest running scheme of its kind anywhere in the world. It is run by Butterfly Conservation and the Centre for Ecology & Hydrology and involves thousands of volunteers across the UK.
The data shows that three-quarters of threatened butterfly species increased from 2009 levels although most remain in long-term decline.
Over three-quarters of the UK's butterflies have declined over recent decades and almost half are seriously threatened, so the results for threatened species come as welcome news.
Dr Tom Brereton, Head of Monitoring at Butterfly Conservation said: "Over the last decade, Butterfly Conservation has developed a large number of landscape scale projects with a wide range of statutory and non-statutory partners to improve and restore habitats for threatened butterflies.
"This has particularly helped the Marsh Fritillary and more recently the Wood White and some other species too are beginning to recover. It shows these projects are working, given time. This is extremely welcome news and shows that we can reverse butterfly losses if the effort can be maintained. There's no doubt that other wildlife is benefitting too."
Dr Marc Botham, Butterfly Ecologist at the Centre for Ecology & Hydrology said:
"The continued dedication of thousands of volunteers enables us to analyse both short and long-term trends in the abundance of butterflies.
"Butterflies are highly sensitive to how our countryside is changing and the UKBMS data has revealed how butterflies are already being impacted by climate change as well as whether our conservation measures are working."