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Butterfly egg chasers defy freezing cold to count a winning streak

Berkshire, Buckinghamshire & Oxfordshire Wildlife Trust's hairstreak butterfly egg count at Leaches Farm Nature Reserve near Bicester. Picture: Hayley Beck

There’s looking for a needle in a haystack, then there’s looking for a butterfly egg in a hedgerow – in the freezing cold.

That is how 15 nature lovers started their year in an important annual tradition.

The staff and volunteers from Berkshire, Buckinghamshire & Oxfordshire Wildlife Trust (BBOWT) spent four hours in icy weather on Tuesday hunting for the tiny, ball bearing-sized eggs of the rare and beautiful brown hairstreak butterfly.

The speckled species is under threat in England from habitat destruction, but the Wildlife Trust creates and maintains tangled blackthorn hedgerows where it likes to lay its eggs at nature reserves near Bicester.

The Tuesday team, armed with powerful magnifying glasses, combed the thickets at Leaches Farm and nearby Ludgershall Meadows and counted an incredible 219 tiny white eggs.

The last time they searched these sites in 2016, the team found just 39 eggs – making this year’s total a 200 per cent increase.

The number of eggs the brown hairstreak lays from year to year can vary greatly because of factors such as weather, but the Trust is still counting the 2024 total as a win for wildlife.

Colin Williams, Senior Ecology Officer at BBOWT, said:
“This is a really brilliant result, especially for the members of our team who spent four hours hunting for eggs in the freezing cold this week.

“We are currently living through a nature and climate crisis, and the numbers of so many of our beloved species are declining across the UK, especially butterflies. The hedgerow habitat at these sites, like the habitats at all our nature reserves, is painstakingly maintained by our staff and our amazing, dedicated volunteers, and the fact that we counted more than 200 hairstreak eggs this week is absolutely a testament to their brilliant work.

“We’d like to thank all our staff and volunteers for the invaluable work they do which makes a real difference to our local wildlife.”

The good result for brown hairstreaks comes after the Trust made several wildlife records at its nature reserves last year.

In the summer, volunteers counted a record 303 glow worms at the charity’s Whitecross Green Wood reserve, also near Bicester. At the same site they also recorded a rare southern migrant hawker dragonfly breeding in a brand new pond – the first time the species has ever been recorded breeding in Oxfordshire.

At a time when climate change, habitat loss and pollution are threatening many species, the Trust put these record results down to the excellent work of its staff and volunteers creating and maintaining important wildlife habitat at its nature reserves.

In order to continue its work, in September the Trust launched its biggest-ever appeal, The Nature Recovery Fund, aiming to raise £3 million in three years to help it tackle the nature and climate crisis. Find out more at

Main image: Berkshire, Buckinghamshire & Oxfordshire Wildlife Trust’s hairstreak butterfly egg count at Leaches Farm Nature Reserve near Bicester. Picture: Hayley Beck