Rare butterflies have enjoyed a bumper summer basking at some of the Englefield Estate’s sunny enclaves following habitat improvement work.
Graylings have been designated the highest conservation status by government advisory body the Joint Nature Conservation Committee, with numbers declining by 58 per cent between 1976 and 2014.
But, according to West Berkshire conservationists, a colony has been thriving at conifer plantations and former gravel pits within the Estate near Mortimer.
The grayling is a master of disguise: when it settles, the butterfly tucks its large brown mottled forewings behind patterned grey hindwings, turns to face the sun before leaning to minimise its shadow, and vanishes.
So under threat is the species that a count of one to 10 on any given summer day would have been considered a positive result, however on one July day alone, an eagle-eyed enthusiast was pleasantly surprised to record 154 graylings at the Estate’s Hundred Acre Piece.
The area provides the ideal habitat for the butterflies which favour sheltered, sunny, dry sites such as heathlands, coastal sand dunes and disused quarries.
At the western end of Hundred Acre Piece is a restored gravel pit and bare ground with a sparse covering of heather and fine grasses, surrounding a small lake. To the east of the gravel pit, a stony track runs north to south, separated from the pit by a ditch and a heather-covered bank; arguably the best place to spot a grayling.
The Estate’s forestry team has been working hard to improve the habitat for the species over the last two years. Work has included widening woodland access routes which promote biodiversity, known as ‘rides’, within the Estate’s conifer woodlands.
As a result of increased sunlight on the forest floor, more diverse ground flora can establish, in turn providing a food and nectar source for a wide range of invertebrates, including graylings.
Doubling up as wildlife corridors, rides link previously isolated areas of open space within the woodlands, increasing the area of suitable habitats for many vulnerable species for which woodland edge habitat is so important.
For the last four years, the Upper Thames branch of Butterfly Conservation has hosted a walk at Hundred Acre Piece during the grayling flight season. This year’s walk in August fell four weeks after the lofty count mid-July, with jubilant walkers spotting around 100 graylings.
Jan Haseler, the branch member who conducted the survey, said: “By the end of the walk, almost everyone had been perched on by a grayling at some point.
“Hundred Acre Piece has a variety of good butterfly habitats, in particular the areas of bare ground and the sheltered rides with wide flowery margins.
“In total, 28 species have been recorded there, including less common species such as green hairstreak, white admiral, marbled white, silver-washed fritillary and small heath.”
Butterflies like warmth and feed on nectar so leaving areas where they can soak up the sun’s rays and planting nectar-rich flowers like bluebells, lavender and primroses, as well as herbs, nettles and trees and shrubs such as holly, will encourage them into your garden.