The Gaboon viper (Bitis gabonica) is a viper species found in the sub-Saharan Africa. Like all other vipers, it is a highly venomous snake. It is the largest member of the genus Bitis, and it has the longest fangs of any venomous snake - up to 2 inches (5 cm) in length – and the highest venom yield of any snake.
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Highly venomous animals are able to produce the most toxic venom which is considered to be one of the most debilitating and potentially deadly.
NoNot a migrant
Animals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
The Gaboon viper has the longest fangs (up to 5 cm) and the highest venom yield of any snake. The head is large and triangular, while the neck is greatly narrowed. A pair of "horns" is present between the raised nostrils. The eyes are large and moveable. The color pattern consists of a series of pale, subrectangular blotches running down the center of the back, interspaced with dark, yellow-edged, hourglass markings. The flanks have a series of fawn or brown rhomboidal shapes, with light vertical central bars. The belly is pale with irregular brown or black blotches. The head is white or cream with a fine, dark central line, black spots on the rear corners, and a dark blue-black triangle behind and below each eye. The iris color is cream, yellow-white, orange, or silvery.
Gaboon vipers are found in Guinea, Ghana, Togo, Nigeria, Cameroon, Equatorial Guinea, Gabon, Republic of the Congo, DR Congo, northern Angola, Central African Republic, South Sudan, Uganda, Kenya, eastern Tanzania, Zambia, Malawi, eastern Zimbabwe, Mozambique, northeast KwaZulu-Natal Province in South Africa and also in Sierra Leone and Liberia in West Africa. Gaboon vipers are usually found in rainforests and nearby woodlands. In Tanzania, they are found in secondary thickets, cashew plantations, and in agricultural land under bushes and in thickets. In Uganda, they live in forests and nearby grasslands. They also do well in reclaimed forest areas: cacao plantations in West Africa and coffee plantations in East Africa. They have been found in evergreen forests in Zambia. In Zimbabwe, they only occur in areas of high rainfall along the forested escarpment in the east of the country. In general, they may also be found in swamps, as well as in still and moving waters. They are commonly found in agricultural areas near forests and on roads at night.
Gaboon vipers are solitary and primarily nocturnal creatures. They have a reputation for being slow-moving and placid. They usually hunt by ambush, often spending long periods motionless, waiting for suitable prey to pass by. However, they may also hunt actively, mostly during the first six hours of the night. They are usually very tolerant snakes, even when handled, and rarely bite or hiss, unlike most vipers. However, bites by bad-tempered individuals do occur. Locomotion is mostly rectilinear, in a sluggish "walking" motion of the ventral scales. They may writhe from side to side when alarmed, but only for short distances. If threatened, Gaboon vipers may hiss loudly as a warning, doing so in a deep and steady rhythm, slightly flattening the head at the expiration of each breath. Despite this, they are unlikely to strike unless severely provoked; however, they are one of the fastest-striking snakes in the world.
Bites from this species are extremely rare because their nature is unaggressive and their range is limited to rainforest areas. Since they are sluggish and unwilling to move even when approached, the humans they bite are usually those accidentally stepping on them, and even then they may not be bitten. When a bite does occur, it should always be considered a serious medical emergency. Even an average bite from an average-sized specimen is potentially fatal. Antivenom should be administered as soon as possible to save the affected limb, or indeed the victim's life. Since their venom glands are enormous, each bite produces the second-largest quantity of venom of any venomous snake; this is partially because, unlike many African vipers, such as the puff adder, the Gaboon viper does not release after a bite, which enables it to inject larger amounts of venom. Yield is probably related to body weight, as opposed to the milking interval. In humans, a bite from a Gaboon viper causes rapid and conspicuous swelling, intense pain, severe shock, and local blistering. Other symptoms may include uncoordinated movements, defecation, urination, swelling of the tongue and eyelids, convulsions, and unconsciousness. Blistering, bruising, and necrosis may be extensive. Sudden hypotension, heart damage, and dyspnoea may occur. The blood may become incoagulable, with internal bleeding that may lead to haematuria and haematemesis. Local tissue damage may require surgical excision and possibly amputation of any affected limb. Healing may be slow, and fatalities during the recovery period are not uncommon.
Gaboon vipers are carnivores that feed on a variety of birds and mammals, many different species of rodents, including field mice and rats, as well as hares and rabbits.
Gaboon vipers breed between September and December. During this time males engage in combat. This starts with one male rubbing its chin along the back of the other. The second male will then raise its head as high as possible. As they both do the same, the necks intertwine. When the heads are level, they turn towards each other and push. Their bodies intertwine as they switch positions. They become oblivious to everything else, continuing even after they fall off a surface or into water. Sometimes they intertwine and squeeze so tightly that their scales stand out from the pressure. They have also been observed to strike at each other with their mouths closed. Occasionally, the combatants will tire and break off the fight by "mutual consent", resting for a while before resuming once more. The event is settled when one of the two succeeds in pushing the other's head to the ground and raising its own by 20-30 cm. Females usually give birth to 8-43 live young in late summer. Gestation takes about 7 months. Snakelets are 30 cm long at birth and don't need parental care.
There are no major threats to Gaboon vipers at present.
The IUCN Red List and other sources don’t provide the number of the Gaboon viper total population size. However, the South African subpopulation is estimated to number 2,000-3,500 mature individuals. Currently, this species is classified as Vulnerable (VU) on the IUCN Red List, and its numbers today are decreasing.
Due to their diet habits, Gaboon vipers play an important role in their ecosystem; they help to control populations of rodents.