Gaboon viper

Gaboon vipers live in African forests.

They hide among the fallen leaves on the ground.

Gaboon vipers live in forests: rainforest, drier forest, forest that is growing back, and patchworks of forest, savanna and farmland. They are found from Nigeria across central Africa to Uganda, with smaller groups in Kenya and Tanzania, and south to Angola, Zambia, Mozambique, Zimbabwe and a strip of coastal forest in South Africa.

They live from sea level up to about 2,100 meters. They need some forest or bush cover nearby: where it is all cleared, they soon disappear.

The IUCN gives a range from Nigeria to the Democratic Republic of the Congo and Uganda, with sporadic records in South Sudan and disjunct populations further east in Uganda, Kenya and eastern Tanzania (where it is restricted to coastal and montane forest fragments), south to Angola and Mbala in Zambia, and apparently isolated populations in southeastern Africa as far as coastal northern Zululand, South Africa. West of the coastal savanna zone of Benin it is replaced by Bitis rhinoceros. Habitat: moist and dry forest, mature and secondary, and forest-plantation mosaics with Guinean savanna; even gardens in towns surrounded by forest; more closely tied to rainforest than most Bitis species and lost rapidly where no forest or bush cover is left; in South Africa mainly coastal dune forest. Elevation 0 to 2,100 m (IUCN).

The Gaboon viper lies very still.

When a mouse or a rat comes close, it catches it.

A Gaboon viper is an ambush hunter. It lies perfectly still among the fallen leaves, sometimes for a long time, until an animal walks close enough to catch.

It eats mostly small mammals such as rats, and also birds that feed on the ground, frogs and lizards. It can even eat a small forest antelope.

The IUCN gives a diet mainly of small mammals, with lizards, birds and frogs also taken, and even small forest antelopes (Luiselli and Akani). ADW lists rodents, ground-feeding birds such as francolins and doves, frogs and toads, and records of giant rats (Cricetomys gambianus), brush-tailed porcupines (Atherurus africanus) and royal antelopes (Neotragus pygmeus) eaten. It is mostly an ambush predator, camouflaged in leaf litter and motionless for long periods until prey comes within reach (Toronto Zoo).

The Gaboon viper has big eyes.

It can look forward and backward.

A Gaboon viper's eyes are large and set well forward on its head. It can move them so that it looks forward and backward, a wider range of eye movement than other snakes have.

When it is asleep, its eyes stay still and its pupils become very small; when it wakes, they suddenly open wide and start moving again. Like other vipers, it also notices vibrations and smells.

Toronto Zoo: the eyes are large, movable and set well forward, so the snake can look forward and backward, a wider range of eye movement than other snakes; they often flick back and forth, and in sleep the eyes stay still with strongly contracted pupils, which dilate suddenly on waking; the iris may be cream, yellow-white, orange or silvery. ADW notes that, like other vipers, it detects vibrations, chemical signals and visual cues.

There are fewer Gaboon vipers than before.

They need their forests to stay.

The Gaboon viper is listed as vulnerable: its numbers are thought to be going down. In many places it is caught for food and sold in markets, and its skin is made into leather goods. It is also lost when forest is cleared for big plantations, because it cannot live where no wild plants are left. Some are caught for the pet trade, but that is not a major threat.

In South Africa, where most of its forest is protected, there were thought to be 2,000 to 3,500 adults (a 2009 estimate), and that population is presumed to be stable.

Vulnerable A2abd (Luiselli, Beraduccii, Howell, Msuya, Ngalason, Chirio, Kusamba, Gonwouo, LeBreton, Zassi-Boulou and Chippaux; Global; assessed 24 October 2019, published 2021; trend decreasing): a decline provisionally estimated at up to 30% over three generations, particularly in Nigeria and the Democratic Republic of the Congo, from heavy harvesting for food and sale in bushmeat markets and continuing habitat loss. At four well-protected Nigerian sites, numbers fell by about 79 to 82% between 1999 and 2003 (Reading et al. 2010), for reasons not established. Skins are used for leather goods; the pet trade involves moderate numbers and is not a major threat; monoculture plantations remove the native vegetation it needs; disease has caused local losses in the DRC. South Africa: 2,000 to 3,500 mature individuals, presumed stable. Not listed by CITES; IUCN recommends monitoring trade and harvest, limiting habitat loss and further genetic research.