ONE of the UK’s most widespread butterflies has suffered its worst year on record, Oxfordshire scientists have discovered.

Researchers at Wallingford's Centre for Ecology and Hydrology have revealed that the UK populations of the Small Copper butterfly fell by almost a quarter in 2015 compared to 2014.

Working with national charity Butterfly Conservation on their UK Butterfly Monitoring Scheme, the scientists concluded the Small Copper is now "in a state of significant decline".

Previous research suggested the butterfly has suffered substantial declines over the past century due to habitat loss, but unusual weather in recent years may be aggravating this decline.

In 2015, a dry spring was followed by the coldest and wettest summer for three years, and 34 of the 57 butterfly species monitored by the scheme experienced declines, with the lack of summer warmth a factor in this.

Dr Marc Botham, butterfly ecologist at the Centre for Ecology and Hydrology, stressed that butterflies' relationship with the changing climate was far from simple.

He said: "2015 was a mixed year.

"Much of the summer was cooler than average resulting in annual declines in many species.

"Some species had a good year emphasising the complex relationship between weather and annual fluctuations in butterfly populations."

Heath Fritillary, one of the UK's scarcest species, suffered its worst year on record with numbers down 16 per cent compared to 2014.

The rare British race of the Swallowtail suffered the largest decline of any species with numbers down 65 per cent compared to 2014.

Widespread butterflies also experienced a poor year with garden visitors the Peacock and Small Tortoiseshell down 21 per cent and 44 per cent respectively.

Other species, however, seemed to thrive, with The Marbled White and Brimstone experiencing their best years on record.

The Painted Lady saw its numbers rise by 200 per cent.

The Centre for Ecology and Hydrology co-ordinates the UK Butterfly Monitoring Scheme with Butterfly Conservation and the British Trust for Ornithology, but much of the actually counting out in the field is done by volunteers.

The hope is that by monitoring population numbers, scientists can pin point the best ways to help species survive.

Sarah Harris of the British Trust for Ornithology said: "It is thanks to the dedicated and enthusiastic volunteers across the UK who take part in the UKBMS scheme that we have such a clear picture of what is happening to our butterflies, both long-term and between years; without these brilliant citizen scientists we would know a great deal less.

"Many thanks to all those who took part and made this report possible."