Britain's butterflies have been breaking records by emerging earlier this spring than in any previous year.
Some, like the Black Hairstreak, one of our rarest butterflies, were on the wing more than a week earlier than ever before.
The endangered Lulworth Skipper and the Small Copper also were flying earlier than ever before - in the case of the Lulworth Skipper seven weeks before it is normally seen. Several others emerged almost a month ahead of usual.
This year's figures indicate a long-term trend that is believed to be linked to climate change. The extremely warm April weather appears to have accelerated the trend.
Dr Martin Warren, Chief Executive of Butterfly Conservation, said: "2011 is breaking a lot of records for the earliest sightings of many butterflies. This is almost certainly to do with the very hot dry spring.
"Many of the butterflies we've already seen will be having second broods - which means there could be a profusion of butterflies in July and August.
"Next month Butterfly Conservation will be endeavouring to get as many people as possible to participate in the nationwide Big Butterfly Count. This will help scientists determine exactly what is happening to our butterfly populations."
The chocolate-coloured Black Hairstreak is one of our rarest and most threatened species and is usually seen in late June. It is threatened by the planned route through Buckinghamshire of the new London-Birmingham HS2 High Speed rail line.
But this year, the butterfly, which is restricted to a handful of sites in the East Midlands, was first recorded on 24 May.
The Small Copper, which typically emerges in the first week of May, was seen on 9 March this year - more than a month earlier than usual.
Butterfly Conservation says Britain's butterflies appear to have been emerging increasingly early in the year over recent decades - and as a result 10 years ago it started monitoring precise dates for emergence.