This video says about itself:
14 August 2013
The enigmatic European Adder (Vipera berus) is one of the hardiest and widespread snakes on earth, and is Britain’s only venomous snake. Unfortunately, it is suffering declines due to a variety of ecological factors. Here we have a fantastic encounter with a creature that’s becoming increasingly difficult to see.
Translated from the Dutch RAVON herpetologists:
12 December 2015 – The Year of the Adder is almost over; a good time to see how things are with the adder populations in the Netherlands. Over the last 20 years, the adder is stable, as evidenced by data from the Monitoring Network for Reptiles. However, the decline had already happened in the decades before that; this is also the reason why the adder on the Red List.
Year of the Adder report: here.