Adders were surely once common throughout the Chilterns. Its patchwork of heaths, commons and ancient woodlands would have been ideal habitat. Creeping urbanisation and mechanised farming has led to increased fragmentation of habitats and the decline of adder populations.
A dwindling population of adders has been recorded in woodland in South Oxfordshire at the southern boundary of the Chilterns AONB – there may be others.
To have a realistic chance of seeing adders you need to journey south of the M4 corridor where significant areas of heath do support adders in reasonable numbers. The best time to see them is March or April when the male adders are out basking. In May the smaller black and grey males compete for the much larger, brown females. You’ll need to tread softly – although adders have no hearing, they can sense vibration, lying in wait to ambush prey.