Mixed outlook for Scottish butterflies

The latest Scottish Biodiversity Indicator has reported that Scotland's butterfly populations continue to show winners and losers in the face of climate change and habitat loss.

Butterflies are a familiar sight across Scotland in the summer months. Some, such as Meadow Brown and Small Tortoiseshell, inhabit a range of habitats and are commonly found throughout Scotland, and are known as 'generalists'. Others, known as 'specialists', are much more restricted by environment preferences and are sometimes only found in a certain semi-natural habitats.

Scotland's specialist butterflies have declined by 67 per cent since 1979. Three species have declined particularly significantly — Small Pearl-bordered Fritillary (over the past 10 years), Large Heath and Grayling.

Small Pearl-bordered Fritillary has declined significantly across Scotland over the past decade (Photo: Dave Hutton)

Generalists such as Small Skipper and Essex Skipper are benefiting from climate change and have expanded their range into southern Scotland. Three generalist butterflies show climate-driven, significant long-term population increases — Peacock, Speckled Wood and Orange-tip. Regular migrant butterflies, including Red Admiral, are also growing in number.

Habitat loss and change through intensification of agricultural and forestry practices, climate change and increased nitrogen deposition are important factors linked to the declines.

In Scotland butterflies are monitored through the UK Butterfly Monitoring Scheme (UKBMS). Volunteers walk fixed route transects weekly from April to September each year. The indicator describes trends for 20 of the 34 regularly occurring butterfly species in Scotland at 436 sample locations. The UKBMS is operated by Butterfly Conservation, the Centre for Ecology & Hydrology and the British Trust for Ornithology.

The Scottish Biodiversity Indicator report can be found online here.