Sir David Attenborough has warned that UK butterflies face a critical summer after a string of poor years has seen the numbers of many common species decline.

Last year was the fourth worst on record for butterflies and Sir David is urging people across Wiltshire to take part in the Big Butterfly Count survey to help reveal how widespread species are faring this summer.

Common species such as the small tortoiseshell, peacock, meadow brown and gatekeeper suffered declines in 2016, but the warm, dry spring and early summer this year could offer butterflies some respite.

The Big Butterfly Count is the world’s largest butterfly survey, which encourages people to spot and record 18 species of common butterflies and two day-flying moths during three weeks of high summer.

Families are being invited to take part in their own garden or by attending a free guided butterfly walk from 10am on Saturday July 15 at Black Dog Woods, between Frome and Westbury.

Information can be found at www.butterfly-conservation.org/WiltsBBC

Butterfly Conservation president, Sir David said: “The next few weeks are a vital period for our butterflies. They need to make the most of this chance to feed and breed.

“In the last decade our butterflies have experienced several poor years and although resilient, they simply cannot sustain repeated losses.”

More than three-quarters of the UK’s butterflies have declined in the last 40 years with some common species, such as the small tortoiseshell, suffering significant slumps.

This year’s count follows new findings that butterflies are declining more rapidly in urban areas than in the countryside.

As many Big Butterfly Counts take place in gardens, parks and urban green spaces, this year’s results from these habitats will help inform conservationists on how to make our urban landscapes more butterfly-friendly.

The Big Butterfly Count runs from July 14 to August 6. Taking part is easy. Find a sunny spot and spend 15 minutes counting the butterflies you see and then submit sightings online at www.bigbutterflycount.org or via the free Big Butterfly Count app.