Butterfly Viper

## Description

The Butterfly viper is a venomous snake found in the forests of West and Central Africa. This large viper is known for its striking coloration and prominent nasal "horns." The color pattern consists of a series of 15-18 blue or blue-green, oblong markings, each with a lemon-yellow line down the center. These are enclosed within irregular, black, rhombic blotches. A series of dark crimson triangles run down the flanks, narrowly bordered with green or blue. Many of the lateral scales have white tips, giving the snake a velvety appearance. The top of the head is blue or green, overlaid with a distinct black arrow mark. The belly is dull green to dirty white, strongly marbled, and blotched in black and gray. Western specimens are more blue, while those from the east are more green. Female Butterfly vipers grow larger than males.

## Distribution

Butterfly vipers are found from Guinea to Ghana in West Africa, and in Central Africa in the Central African Republic, southern Sudan, Cameroon, Gabon, Congo, DR Congo, Angola, Rwanda, Uganda, and western Kenya. They live in forested areas, often near water, and rarely venture into woodlands.

## Behavior

Butterfly vipers are solitary and primarily nocturnal creatures. They hide during the day in leaf litter, in holes, around fallen trees or tangled roots of forest trees. Their vivid coloration actually gives them excellent camouflage in the dappled light conditions of the forest floor, making them almost invisible. Although mainly terrestrial, they are also known to climb into trees and thickets, where they have been found up to 3 m (9.8 ft) above the ground. This climbing behavior is aided by a partially prehensile tail. They are sometimes found in shallow pools and have been described as powerful swimmers. Butterfly vipers prefer to hunt by ambush, and probably spend much of their life motionless, waiting for prey to wander by. They are slow-moving but capable of striking quickly, forwards, or sideways, without coiling first or giving a warning. Holding them by the tail is not safe; as it is somewhat prehensile, they can use it to fling themselves upwards and strike. Butterfly vipers are generally placid creatures. When approached, they often reveal their presence by hissing that sounds almost like a shriek; it is said to be the loudest hiss of any African snake.

## Diet

Butterfly vipers are carnivores. They feed mainly on small mammals, but in wetland habitats, they are also known to take toads, frogs, and even fish.

## Reproduction

Butterfly vipers are viviparous meaning they give birth to live young. In West Africa, females produce between 6 and 38 young in March-April at the beginning of the rainy season. Each neonate measures 18-25 cm (7-10 in) in total length and is venomous at birth. In eastern Africa, the breeding season is indefinite.

## Population

### Threats

There are no major threats facing Butterfly vipers at present.

### Number

The Butterfly viper population number is unavailable at present from open sources and its conservation status has not been evaluated.

## Fun Facts

Historically the Butterfly viper was referred to as the Rhinoceros viper because it has a distinctive set of two or three horn-like scales on the end of the nose, the front pair of which may be quite long.

The Butterfly viper is often called the River Jack because it lives in tropical forests, often near wetlands.

Butterfly vipers make a sort of hissing noise through their nose which is a part of their respiratory function.

The Butterfly viper is considered to be one of the most dangerous snakes in Africa. Small doses of its venom can be deadly.

When not in use, the Butterfly viper's fangs are folded up into the roof of its mouth. The snake has the ability to control the movement of its fangs. Simply because the Butterfly viper may open its mouth does not mean that the fangs will flip down into place. These fangs penetrate deep into the victim and the small doses of venom flow through the hollow fangs into the wound.