Adult Female Adder | Joel Walley Wildlife Photography
Gravid female Adder (Vipera berus) basking on the decomposing reeds of a fen, Anglesey. Female adders have a brown zigzag compared to the black zigzag of the males. Females give birth to live young, presumably an adaptation to living in a colder climate. Adders are the most Northerly occurring snake species in the world, and are the only species found within the arctic circle.