This spreadsheet is the underlying data for the biodiversity indicator C6, Insects of the wider countryside (butterflies).
Butterflies respond rapidly to changes in environmental conditions and habitat management, occur in a wide range of habitats, and are representative of many other insects, in that they utilise areas with abundant plant food resources. Butterflies are complementary to birds and bats as an indicator, especially the habitat specialists, because they use resources in the landscape at a much finer spatial scale than either of these groups.
The indicator consists of two measures of annual butterfly population abundance: the first for specialist butterflies (species strongly associated with semi-natural habitats such as unimproved grassland) and the second for butterflies found in both semi-natural habitats and the wider countryside. Both measures show marked fluctuations from year to year, principally in response to weather conditions.
This is one of a suite of 24 UK biodiversity indicators published by JNCC on behalf of Defra; the latest publication date was 19 January 2016 - for indicator C6 the latest data are for 2014. The supporting technical document details the methodology used to create the indicator.