9 Apr 2014

Warm summer gives butterflies boost

Weather Presenter

Butterflies saw their fortunes improve in summer 2013, following their worst year on record in 2012. However, numbers were still below normal, according to the UK butterfly monitoring scheme.

Butterfly on a flower

46 of the 56 species studied saw numbers increase, compared with the washout summer of 2013, which was the wettest in 100 years.

According to experts, last year’s warm summer allowed butterflies to make the most of conservation measures put in place over the last decade to help them thrive.

Rare species, such as the Lulworth Skipper and critically endangered High Brown Fritillary, saw numbers up by 162 and 133 per cent respectively.

More common species also saw improvements, with the small, large and green-veined whites all bouncing back from their worst year on record in 2012, to above average numbers last year.

The summer warmth also helped garden favourite, the small tortoise shell, record its best year in a decade.

Even though these increases in numbers have been recorded, they were still below normal – partially caused by last year’s record cold spring.

Experts say that butterflies need a warm spring and summer this year, to help them sustain their recovery from the lows of 2012.

Dr Tom Brereton, head of monitoring at Butterfly Conservation, said: “After the worst year ever, there was bound to be a bounce-back, and quite a few species made a better recovery than expected, so it’s encouraging.”

CEH butterfly ecologist Dr Marc Botham said: “Annual changes are largely associated with the weather. However, the data show that a number of species have been significantly declining over the last 38 years.”

The UK Butterfly Monitoring Scheme involves thousands of volunteers collecting data every week throughout the summer from more than 1,000 sites across the UK.