Rare butterflies bounce back after landowners in Wales cut back on flailing hedges

"Conservationists have now persuaded landowners to cut hedges in a more gentle rotation, with sections left uncut for up to three years, to enable more eggs to survive over winter. The caterpillars emerge with the foliage in spring and hatch into adult butterflies in July. The brown hairstreak is difficult to spot as a butterfly but every winter volunteers assess its populations by counting its minuscule cream-coloured eggs, which with careful searching are visible on the bare branches of blackthorn."

"Volunteers for Butterfly Conservation this winter counted 276 brown hairstreak eggs on blackthorn hedges on the north verge of the busy A40 west of Llandeilo and 117 eggs on the south verge both record counts and a 50% increase on the previous year. Three nearby sections of hedgerow also recorded increases after sympathetic management, including the planting of new blackthorn bushes."

"The upturn comes after more than a decade of decline for the butterfly in the Tywi valley, which almost disappeared in the region due to increased mechanical flailing of hedgerows and patches of scrub. When Butterfly Conservation found a small remnant population in 2021 west of Llandeilo, they began annual egg counts and worked with the National Trust and the South Wales Trunk Road Agent, to get more blackthorn planted, as well as protecting hedgerows from annual flailing."

Record counts of brown hairstreak eggs were recorded on blackthorn hedges west of Llandeilo after landowners changed hedge cutting practices. Volunteers counted 276 eggs on the north verge of the A40 and 117 eggs on the south verge, a 50% increase on the previous year. Three nearby hedgerow sections also showed increases after sympathetic management and new blackthorn planting. Areas that continued annual mechanical flailing saw steep declines, dropping from an average of 60 eggs to four. Conservation groups worked with the National Trust and road agents to plant blackthorn and protect hedgerows by leaving sections uncut for up to three years.

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