Otherwise known as Bothriechis schlegelii after the German ornithologist Hermann Sclegel, the eyelash viper is a relatively small venomous pit viper found in Central and South America. This snake is arboreal, using its strong tail to move about trees, typically at night. It likes a low altitude and tends to live near a permanent water source, like the sea. Females are larger than males, and they rarely exceed 2.5 feet. This one was spotted in June, 2011 at La Selva Biological Station, Costa Rica. I saw one in a tree at knee-level in broad daylight at the Cahuita National Park.
South American legend holds that eyelash vipers will wink at their victims after striking, though science says that snakes are physiologically incapable of such behavior. They consume rodents, frogs, lizards and little birds using hypodermic needle-like fangs to attack prey. Not typically aggressive, eyelash vipers will strike when bothered, so leave this one alone.