With Easter still a few months off, the team from BBOWT embarked on its annual egg-hunt tradition, searching for prizes more valuable than chocolate.

The rare brown hairstreak butterfly is found in select areas across the south of Britain, with declining numbers from habitat loss resulting in its Vulnerable designation on the Butterfly Red List. Spending much of its adult life hidden high in hedgerows and in the treetops, this elusive butterfly is monitored by counting its eggs in the winter.

Last Tuesday, a group of fifteen BBOWT volunteers and staff braved the cold to scour through blackthorn hedgerows at Asham Meads nature reserve in Oxfordshire, hoping to spot these tiny white eggs which measure just 1mm in diameter.

BBOWT’s Senior Ecologist, Colin Williams, said:
“This count was only possible because we have a fantastic army of volunteers – searching hedgerows for an egg the size of a pinhead is not something you want to do on your own. The brown hairstreak specifically needs new areas of blackthorn growth to lays its eggs, as the caterpillars feed on its leaves once they’ve hatched. Each year we cut a section of blackthorn across our reserve to ensure that we have new growth in our hedgerows. Fortunately, this also helps us to narrow down the area for our search!”

The team recorded a total of 43 eggs, a 33% increase on the 29 found in 2022, although still below the site’s 2009 peak of 67. This follows last year’s count at Leaches Farm where an incredible 219 eggs were spotted, the highest number found on the reserve to date.

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

Colin Williams continued:
“With 2024 being an alarming year for our British butterflies, this positive result is a fantastic endorsement for the way we manage our nature reserves. We hope that other landowners and land managers will be encouraged to safeguard their hedgerows which are a vital refuge for brown hairstreaks and other butterflies against the increasingly severe and unpredictable weather events brought on by climate change. 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.”

In order to continue its work, the Trust launched its biggest-ever appeal, The Nature Recovery Fund, in September 2023, aiming to raise £3 million in three years to help it tackle the nature and climate crisis. Find out more at bbowt.org.uk/sos

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