West African green mamba, Hallowell's green mamba
The western green mamba (Dendroaspis viridis ) is a long, thin, and highly venomous snake species of the mamba genus, Dendroaspis. This species was first described in 1844 by American herpetologist Edward Hallowell. The western green mamba is a fairly large and predominantly arboreal species, capable of navigating through trees swiftly and gracefully. It will also descend to ground level to pursue prey such as rodents and other small mammals.
The western green mamba is a shy and agile snake that lives mainly in the coastal tropical rainforest, thicket, and woodland regions of western Africa. Its venom is a highly potent mixture of rapid-acting presynaptic and postsynaptic neurotoxins (dendrotoxins), cardiotoxins and fasciculins. Some consider this species not to be a particularly aggressive snake, but others have suggested that they are extremely nervous and are prone to attack aggressively when cornered. Conflict with humans is low compared to some other species found in the region. Bites to people by this species are quite uncommon. Their mortality rate, however, is high; many of the recorded bites have been fatal. Rapid progression of severe, life-threatening symptoms are hallmarks of mamba bites. Bites with envenomation can be rapidly fatal.
The Western green mamba is a long, thin, and highly venomous snake. It is a fairly large and predominantly arboreal species, capable of navigating through trees swiftly and gracefully. It will also descend to ground level to pursue prey such as rodents and other small mammals. Some consider Western green mambas not to be particularly aggressive snakes, but others have suggested that they are extremely nervous and are prone to attack aggressively when cornered. Conflict with humans is low compared to some other species found in the region. Bites to people by this species are quite uncommon. Their mortality rate, however, is high and many of the recorded bites have been fatal.
Western green mambas are native to West Africa. They occur from the Gambia and southern Senegal to Benin, including the intervening countries (from west to east) Guinea-Bissau, Guinea, Sierra Leone, Liberia, Cote d'Ivoire (Ivory Coast), Ghana, and Togo. These snakes live mainly in the coastal tropical rainforest, thicket, and woodlands. They inhabit areas where the tree cover has been removed, providing that sufficient hedges and thickets remain. They can also be found in some suitably vegetated suburbs, towns, and parklands.
Western green mambas are solitary and communicate with each other only during the mating season. They are mostly diurnal but may be active at night as well. Although they are arboreal, they do commonly go to the ground. In fact, they are equally at home hunting and feeding on prey on the ground or in trees. These snakes pursue their prey, striking rapidly and often until the prey succumbs to the venom. When they want to sleep they seek out tree branches that offer dense cover. Western green mambas are very quick, extremely agile, alert, and nervous snakes. When confronted they will quickly attempt to escape (usually up a tree if possible) and avoid any sort of confrontation. If cornered, they are highly dangerous and will show a fearsome display of aggression, loudly hissing and striking repeatedly.
The western green mamba is classified as a snake of medical importance in western SubSaharan Africa by the World Health Organization, although bites from this species are rare as it is rarely encountered. When bitten, symptoms rapidly begin to manifest, usually within the first 15 minutes or less. The extraordinary speed with which the venom spreads through tissue and produces rapid manifestations of life-threatening symptoms is unique to mambas. Common symptoms of a bite from a western green mamba include local pain and swelling, although uncommon, local necrosis can be moderate, ataxia, headache, drowsiness, difficulty breathing, vertigo, hypotension (low blood pressure), diarrhea, dizziness, and paralysis. Left untreated, new and more severe symptoms rapidly progress. All symptoms worsen and the victim eventually dies due to suffocation resulting from paralysis of the respiratory muscles. Bites with envenomation can be rapidly fatal, which can be possible in 30 minutes.
Similar to the venom of most other mambas, the western green mamba's contains predominantly three-finger toxin agents. The exception is the black mamba, whose venom lacks the potent alpha-neurotoxin as well. It is thought this may reflect the species' preferred prey—small mammals for the mainly land-dwelling black mamba, versus birds for the other predominantly arboreal mambas. Unlike that of many snake species, the venom of mambas has little phospholipase A2. Overall, the venom of the western green mamba is more potent than that of the eastern green mamba, similar or slightly less potent than that of Jameson's mamba, and much less potent than that of the black mamba.
The venom consists mainly of both pre-synaptic and post-synaptic neurotoxins, cardiotoxins, and fasciculins. The toxicity of the venom can vary tremendously depending on various factors including diet, geographical location, age-dependent change, and other factors. The SC and IV LD50 for this species is 0.79 mg/kg and 0.71 mg/kg, respectively (Christensen and Anderson (1967)). One study determined the LD50 of the venom administered to mice via the intraperitoneal (IP) route was 0.33 mg/kg. In another test using mice that were administered the western green mamba's venom via the intraperitoneal (IP) route the LD50 was 0.045 mg/kg. Another experimental IV LD50 toxicity of 0.5 mg/kg has been reported, with an average wet venom yield of 100 mg. Like other mamba species, western green mamba venom is among the most rapid-acting venom of snakes.
Western green mambas are carnivores. They feed mainly on birds and small mammals, including rodents such as mice, rats, and squirrels. Other mammals include bats, tree pangolins, and shrews. They also eat lizards, frogs, and bird eggs.
Female Western green mambas lay up to 14 eggs placing them in rotting trunks or bury in the ground. The incubation period usually lasts 66-88 days. The young hatch green in color and measure 350-440 mm (13.7-17 in) a length. Their first molt occurs in 12-17 days.
There are no major threats to Western green mambas at present.
According to IUCN, the Western green mamba is locally common throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.
