THE Borders is gaining new types of butterfly because of climate change.
While the picture in England is bleak – the number of common butterflies fell by a quarter in the last 10 years – the creatures have fared better in Scotland, while in the Borders new species such as the speckled wood have moved in.
Butterfly Conservation East Scotland branch chairman Dr Barry Prater said: “While the overall UK picture for butterflies is not looking good, here there are still some reasons to be cheerful, although not optimistic. Changes in land use across the Borders have resulted in the loss of valuable wildlife habitats but some important sites for butterflies remain and the district appears to be benefiting from a gradual move north of some species in response to the warming climate.”
The State of the UK’s Butterflies 2011 report by Butterfly Conservation and the Centre for Ecology and Hydrology (CEH) shows populations of specialist species have stabilised in Scotland while their UK counterparts have continued to decline.
It says that while England lost common butterflies, Scotland’s widespread butterflies increased slightly (by 11 per cent).
The report, the first to give a 10-year assessment of species distribution and population changes, puts the differences down to Scotland’s relatively unspoilt landscapes providing habitats and the warming climate.
Several species have expanded their range in Scotland in recent years, including the speckled wood, comma, peacock, and orange-tip. And that would accord with Dr Prater’s findings in the Borders.
The comma arrived within the last five to seven years. The speckled wood has more recently moved in from Northumberland along with the small skipper: “Neither is particularly fussy about where it lives as long as there are plenty of the right sort of common wild grasses on which their eggs can be laid. This is another reason why a spread to new parts of the country is happening quite quickly and easily.
“Both these butterflies are widespread and common across southern Britain, as was another species, the wall, which has undergone dramatic losses through much of central England over the past decade for unknown reasons, and this problem appears to be spreading from the latest survey results. The wall has now colonised much of the Berwickshire coast and has been recorded far inland at Stichill and near Cardrona, which all bodes well for its future here.”
But in Scotland some specialist species are still declining, among them the pearl-bordered fritillary. Here, the small pearl-bordered fritillary, a similar species, is doing well.
But others have been hit including the small blue which has a wingspan of about an inch and the large heath.
Dr Prater said: “The small blue needs the sort of grasslands that grow on thin, often limestone-rich soils and these are limited in the Borders. There is one strong colony left at the coast and there used to be good numbers on the old railway line south from Hawick, but as the disused line became overgrown, its caterpillar food, kidney vetch, diminished and the butterfly disappeared.
“The planting of trees and general land improvements through drainage have reduced suitable habitats for the large heath but the areas where it is found are little visited so it may be that colonies survive but are unrecorded.”
Dr Prater said the charity has strong links with Scottish Natural Heritage, Scottish Borders Council and Forestry Commission Scotland as well as farmers and landowners in the Borders: “The emphasis is to make sure people know where important butterflies and moths are and to advise on how land can be managed to help them.”
He suggests those who want to help butterflies grow plants they feed on, such as buddleias, and leave a few nettles for tortoiseshells and peacocks’ caterpillars. To assist rarer ones, he advises checking places in the countryside which already have good numbers and are not under threat and to let the charity know if things change.
For further information see www.eastscotland-butterflies.org.uk