The adder, the only poisonous snake in the UK, could become extinct in 15-20 years, according to a leading expert.
Nick Milton, who has written a book on adders, said there are only 260 sites with the snakes left in the UK.
He told Radio 4’s Today Programme that because many habitats have fewer than ten adders, the risk that the snake could be wiped out in the next two decades is high.
Mr Milton said one of the greatest threats to adders is pheasants, which are able to kill the reptiles.
The game birds are released in their millions at shooting estates across the UK.
Read more: Could King Charles save the UK’s only poisonous snake? Royal residences could provide a refuge for adders, as an expert warns they could be wiped out in Britain within 15 years