Project allows endangered adders to cross road to breed
How did the adder cross the road? It didn’t – it was too scared. Road-shy populations of the endangered snake are now being given a helping hand thanks to the construction of Britain’s first adder tunnels.
The two tunnels running beneath a road bisecting Greenham and Crookham commons in Berkshire have been designed to appeal to reptiles. Britain’s only venomous snake has vanished from central England because of persecution, habitat fragmentation and the growth of pheasant shoots, with non-native pheasants predating the small vipers.
“We’ve got a biodiversity crisis. We need to be doing new and innovative things,” said Tom Hayward the senior land manager at the Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust (BBOWT) charity. “We need to be thinking outside the box as to how we benefit these species.”
In the past decade, the snakes have disappeared from Buckinghamshire and are all but extinct in Oxfordshire. Greenham Common, which became a nature reserve 24 years ago after the closure of the RAF base, is one of its last strongholds in the region.
The tunnels opened this spring after radio-tagging studies showed two adder populations on the commons were not mixing because of the road. The populations need to meet each other to breed and boost their genetic diversity.
Debbie Lewis, the head of ecology for the BBOWT, said: “The aim is to enable them to mix and become more resilient in the future. At the moment they are isolated populations and genetics is very important in their survival.”
Adders avoid open ground as they risk attack by birds. If one does cross a road it risks being hit by a car. They can live up to 30 years but females do not breed every year, rarely move, and are particularly vulnerable to disturbance.
The tunnels project, funded with £113,000 from Natural England’s Species Recovery Programme, has created snaking corridors of cut branches through the commons, with 100 metres of low sheet metal fencing to funnel the snakes to each tunnel entrance.
Once inside, the snakes are encouraged to slither through by a thick floor of large pebbles that they can grip on and a metal grill roof that allows the sunshine in. The sun warms the pebbles and creates an appealing temperature for the heat-seeking snakes. “We could’ve put heating in, but then the danger is the snakes would’ve never left the tunnels,” said Hayward.
Roger Stace, a land manager for the BBOWT, said: “It would be nice if this could be a showcase and we get other land managers interested in what we’ve done, replicating it and improving it.”