Following the confirmed extinction of the species in neighbouring Warwickshire, concerns have been raised about the future of Britain’s only venomous snake in Oxfordshire.
Experts say the adder is now “all but extinct” in Oxfordshire, with records showing a sharp decline since 2000.
The county’s Local Nature Recovery Strategy indicates just one remaining population in the Chilterns, which was previously reintroduced.
The last confirmed sighting in Oxfordshire was in 2015.
The adder, known scientifically as Vipera berus, is considered very rare in the county.
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The Local Nature Recovery Strategy highlights several pressures on the species, including habitat loss, human disturbance, and predation by gamebirds.
It has proposed measures to protect the remaining population, including creating and improving habitat mosaics and exploring reintroductions in the Chilterns or Cotswolds.
Adders require a diverse mix of heathland, scrub, and woodland edges to thrive, with warm areas for basking and sheltered spots for hibernation.
Warwickshire Wildlife Trust confirmed the extinction of the adder in Warwickshire, where the last confirmed record was in 2004.
The trust’s announcement has brought renewed attention to the adder’s precarious position in the Midlands and central southern England.
The Local Nature Recovery Strategy, published in November 2025, is intended to guide efforts to restore and reconnect habitats across Oxfordshire.
It was prepared following input from more than 3,000 people and organisations.
The situation in Warwickshire serves as a warning for Oxfordshire, illustrating how quickly isolated reptile populations can vanish when habitat networks break down.
Without successful habitat restoration and long-term monitoring, Oxfordshire could face the same outcome.
Adders are most likely to persist in large, connected areas of low-disturbance heathland, moorland, coastal dune and open woodland habitat