Spot the butterfly – it may help to save a vanishing breed

According to a report out today, there are fears many of the UK's common and garden butterflies are at risk, with seven out of 10 native species in decline and half of those threatened with extinction.

Numbers have hit an all-time low in the past three years as bad summer weather has compounded long-term problems caused by loss and degradation of habitat.

Over the last 50 years, changes to land management, from more intensive farming to the rise in conifer plantations, have hit the butterfly hard.

"Species like the meadow brown and small blue are much less widespread than they would have been a few decades ago," says Richard Fox, surveys manager at Butterfly Conservation.

"Fragmentation of habitat has made it difficult, particularly for rarer species, to move around, isolating and damaging populations. Many butterflies use gardens like 'motorway service stations' to feed in while breeding elsewhere, but the fashion for putting down decking or paving over front lawns for driveways has had a real impact."

Accurately monitoring populations of butterflies is notoriously difficult, which is why Butterfly Conservation is now appealing for the public's help. For seven days from tomorrow, the group is asking people to spend quarter-of-an-hour in a garden, park or field and make a note of the species of any butterfly they see there.

The hope is that the information will help build up a much clearer picture of the fortunes of the country's butterflies, and give an indication of the wider health of the country's natural world as a whole.

"Reports suggest numbers of many garden, common or widespread species are down so far this year, but the warm weather will have benefited them," adds Richard. "What we don't know is exactly how much. The information we gather

will also show whether species are moving north as the climate changes and even colonising cities where they were previously not found."

Some common species have seen dramatic declines in recent years, including the small tortoiseshell butterfly, and the wall butterfly, which used to be found all over the countryside, but which has now disappeared from large parts of central and southern England.

However, it's not all bad news. Colonies of the blue butterfly, normally a native of southern England, have been found as far north as Edinburgh in the past few years, and with warm weather boosting numbers of woodland butterfly species, experts have spotted some unusual colour variations.

Matthew Oates, conservation adviser at the National Trust, recently managed to photograph a purple emperor butterfly with particularly rare markings.

"It's difficult to spot as it mostly lives high in the treetops," he says. "Usually, it has white markings on its large purple iridescent wings, but this particular butterfly was missing them. In the heyday of old-fashioned butterfly collections, this particular occurrence was the dream of every collector, purely because there were so few of them.

"Colour variations tend to occur in high populations during good weather, and this July has been very good for woodland butterflies such as the silver-washed fritillary and the white admiral."

However, for every snippet of good news, there are a dozen stories of worrying decline. Since Butterfly Conservation was launched in 1968, it has worked hard to raise awareness of the species' plight.

It is currently running 33 nature reserves, alongside 67 conservation projects and its president, Sir David Attenborough, is keen to get more people on board.

"Butterflies are extraordinary, heart-lifting creatures – visions of beauty and visions of summer," he says. "Butterflies in profusion tell us that all is well with nature. When they decline, it's a warning that other wildlife will be soon heading the same way.

"So with the big butterfly count, we will be doing more than just counting butterflies – we'll be taking the pulse of nature."

n For more information about the count, log on to www.bigbutterflycount.org