S8 Terrestrial Insect Abundance: Butterflies
Dingy Skipper butterfly
Erynnis tages
Population trends in Scottish butterflies (1979-2005)
Results from the UK Butterfly Monitoring Scheme for Scotland
TREND: DIVERGENT | DATA CONFIDENCE: SATISFACTORY |
Butterflies are well-documented, recognisable and popular with the public. The 34 species regularly recorded in Scotland can be divided into two categories: ' specialists' that are largely restricted to blocks of semi-natural habitat and ' generalists' that can utilise a broader range of habitats, including linear features across the countryside. Butterfly indicators can play a role in assessing habitat diversity, habitat fragmentation and impacts of climate change.
Assessment
- Butterflies fluctuated appreciably but increased in abundance by 35% between 1979 and 2005.
- An 51% increase in the abundance of 'wider countryside/generalist' species was statistically significant.
- Species that increased included red admiral Vanessa atalanta (a migrant) and ringlet Aphantopus hyperantus (a species expanding northwards in range).
- Specialist species fared worse than generalists, although the 27% decrease in abundance was not statistically significant.
- Declining species include grayling Hipparchia semele and dark green fritillary Argynnis aglaia.
- Trends could not be calculated for Scotland's rarest and most threatened specialist butterflies (e.g. mountain ringlet Erebia epiphron) owing to data limitations.
Evidence
The distribution and abundance of butterflies has been recorded since 1979, primarily from the UK Butterfly Monitoring Scheme ( UKBMS). The indicator here includes 21 of the 34 butterfly species that occur regularly in Scotland, the remainder being excluded due to insufficient data.