Rescue boost for Scotland's smallest butterfly

The tiny butterfly, which has a wingspan of only 16mm, once existed in colonies stretching along the Scottish coastline and inland locations, where its caterpillar’s sole food, the kidney vetch plant, thrived.

But experts have warned the species could become extinct in Scotland because of habitat loss and adverse weather.

Whole colonies can be wiped out by bad weather and because the species is reluctant to move to other sites.

The species, which suffered a massive drop in Scotland last year, was recently added to the UK’s Red List of species at risk.

Now a project led by the Caithness Biodiversity Group, called “Small is Bluetiful”, is aiming to protect the butterfly in the Dunnet Bay area, the species’ most northerly stronghold, by planting kidney vetch in the dunes.

Members of the Caithness Countryside Volunteers have also scraped back vegetation to open up new areas of bare ground and encourage the natural colonisation of the plant. It is hoped this will further boost the butterfly.

Highland Council ranger Marina Swanson said: “Due to the hard work of our volunteers, we planted out plenty of kidney vetch and opened up suitable new areas for colonisation.

“We are very grateful to our volunteers for all their efforts and are confident the enhanced habitat will make a real difference to the existing colonies of Small Blue Butterflies.”

The Small Blue is the smallest resident butterfly in the UK. According to the charity Butterfly Conservation, the species was down by 74 per cent in numbers north of the border last year.

Populations tend to be very small, meaning a combination of habitat disturbance and bad weather could threaten the survival of the whole species in Scotland.

Scotland is home to 32 resident butterfly species, of which 12 are recorded as priority species under the UK Biodiversity Action Plan and the Scottish Biodiversity List.

In the past 30 years, 22 of Scotland’s native butterflies have declined in range.