The berg adder, also known as the Cape mountain adder, is a very ill tempered little snake, quick to hiss and strike at anything larger than its usual prey of small rodents, amphibians and ground-nesting birds.
The bite of the berg adder contains neurotoxic venom, which often affects the ocular nerves, which could cause temporary blindness, lasting from 4 to 5 days, or even up to 3 weeks in severe cases. The different stages of the blindness include double vision, dilation of the pupils and an inability to focus, followed by complete paralysis of the eyelids.
The adders poison has no direct effect on the repertory system, unlike the venom of the cobras. Eyesight will return to normal with no permanent after-effects.
There are areas in the Transvaal where these snakes occur in large numbers, but they are rarely seen elsewhere because of the difficulty of seeing the snake in the low, thick vegetation of mountain slopes and plateaus