Official statistics for combined UK butterfly trends 1976-2021 were published by Defra on Thursday 13 October 2022, showing how specialist habitat species and wider countryside species are doing.
This publication of Defra statistics covers two measures of annual butterfly population abundance: the first for habitat-specialist butterflies (species strongly associated with semi-natural habitats such as chalky land), and the second for more widespread butterflies found in semi-natural habitats and wider countryside in the UK.
Statistics show that since 1976 the populations of habitat specialists have declined significantly, although the wider countryside species show no significant change. Habitat specialist species, which are vulnerable to the loss and fragmentation of semi-natural habitat, have not recovered from the declines recorded in the late 1970s. These declines have been mainly attributed to the effects of training from the drought conditions experienced in 1976.
Butterflies are considered to provide a good indication of the general state of the environment because they respond quickly to changes in environmental conditions and habitat management, occur in a wide range of habitats, and are representative many other insects, in that they use areas with abundant plant food resources.
Additional technical information on trends can be found in the technical file.
These statistics contribute to a series of indicators due to be updated in December this year (UK Biodiversity Indicators).
The statistics are produced from data collected by the UK Butterfly Monitoring Program (UKBMS), organized and funded by Butterfly Conservation, the UK Center for Ecology & Hydrology (UKCEH), the British Trust for Ornithology (BTO) and the JNCC. The UKBMS is indebted to the thousands of dedicated volunteers who provide data to the programme.