DEFRA publishes new butterfly statistics

DEFRA has published its latest UK and England butterfly indicators, showing that numbers have dropped dramatically nationwide since 1976.

The data form part of a suite of governmental biodiversity indicators and describe grouped measures for habitat specialist and wider countryside butterfly species across the UK from 1976-2017 and wider countryside species in woodland and farmland habitats in England from 1990-2017.

Though better than the previous year, 2017 was relatively poor for butterflies, attributable to periods of poor weather during the spring and summer and preceding winter months.

In the UK, since 1976, the habitat specialists butterflies index has fallen by 77 per cent, while wider countryside abundance is down by 46 per cent.

Wood White is among the habitat specialists to have declined the most across Britain since 1976 (Bob Eade).

Within the overall downward trend, different species showed contrasting fortunes. Habitat specialists suffering the greatest declines since 1976 include Heath Fritillary, Wood White, Lulworth Skipper and Pearl-bordered Fritillary. However, Silver-spotted Skipper, Dark Green Fritillary, Large Heath, Adonis Blue and Silver-washed Fritillary all showed significant increases over the long term. Wider countryside species experiencing the worst downturns since 1976 include White-letter Hairstreak, Wall and Small Tortoiseshell. In contrast, species such as Comma, Marbled White, Speckled Wood and Ringlet increased in number over the time period.

In England, since 1990, the farmland butterfly index has dropped by more than a quarter, while the woodland index is down by 58 per cent. Both measures have shown some recovery since a low point in 2012. The most severely declining woodland species are Small Copper, Wall and White-letter Hairstreak, while farmland species in most rapid decline are Small Tortoiseshell, Wall and White-letter Hairstreak. Ringlet has increased in both habitats since 1990.

Silver-spotted Skipper is one of the few butterflies to show a significant increase over the long term (Bob Eade).

The indicators are compiled by Butterfly Conservation and the Centre for Ecology and Hydrology from butterfly count data collected by volunteer recorders contributing to the UK Butterfly Monitoring Scheme.

Butterflies are regarded as valuable environmental indicators due to their rapid and sensitive responses to subtle habitat or climatic changes and as representatives for the diversity and responses of other wildlife. As such, these results indicate that the UK's countryside is in a poor state for wildlife and that urgent action is required. Butterfly Conservation is working with partners to address butterfly declines through a wide-ranging programme of conservation action.