April

Boomslang (Dispholidus typus)

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Family: Colubridae.

Size: 1.2-1.5m.

Distribution: Widespread African species that has been found in every province in South Africa. The snake is particularly abundant along the southern coast from the tip of the Western Cape through the Eastern Cape and Kwazulu Natal and  into Mpumalanga, where it spreads northwards and westwards into Limpopo, Gauteng and the North West. Although present in every province, the snake is absent from the drier , treeless regions and is thus much rarer in the Free State and the Northern Cape.

Description: Back-fanged snake with a short stubby head and large eyes. The under-belly is strongly keeled to aid the snake in climbing. In terms of colouration, the species is exceptionally variable. Irrespective of this, females tend to be olive/brown throughout their range and males tend to be grass green above Eastern Cape and fluorescent green/yellow with black bars below Kwazulu Natal. It must however be stressed that colouration is incredibly variable with brick red specimens and other variants sometimes being found. In addition, juveniles look different to adults, and carry large emerald eyes which only change colour when they transition into adulthood.

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Habits: Diurnal snakes which are found in a large variety of habitats, most commonly in trees and shrubs, but may descend to the floor to bask or find food.

Reproduction: Oviparous, lays 10-15 eggs in soft soil or in the hollow of a tree trunk.

Subspecies: Although not formally recognised, subspecies have been proposed which would split the species somewhere near the top of the Eastern Cape. The informal classification recognises the boomslangs north of this mark as Dispholidus typus viridis and boomslangs below this mark as Dispholidus typus typus. Males of Dispholidus typus viridis are thought to be solid green while males of  Dispholidus typus typus are believed to be more of a fluorescent green/yellow with black bars. Females tend to be olive/brown irrespective of the proposed subspecies.

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Conservation concern: Least concern, common.

Diet: Chameleons, frogs, tree-living lizards, birds and occasionally rodents.

Danger to man: The boomslang possesses a very dangerous haemotoxic venom capable of killing people. Monovalent antivenom is however available and has been found to be very effective in counteracting the venom. Although dangerous, the snake rarely bites, with most bites being received from snake handlers. There is a big misconception that boomslangs cannot inject venom on larger body parts because they are back-fanged. This is however untrue as boomslangs can open their mouth’s 170 degrees and can thus easily inject venom into a leg or an arm. Due to the placid and shy nature of this snake, there is virtually no chance of simply walking past a tree and being bitten.

Predators: Predatory birds and other snakes.

Similar species: Boomslangs are easily confused with green mambas and members of the genus Philothamnus (green snakes) north of the Transkei because of the uniform green colour.

Interesting Facts: The boomslang has the largest eyes of any African snake and it inflates its throat when threatened.

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Sources:

Branch, B. 20016. Snakes and other Reptiles of Southern Africa. Cape Town. STRUIK Nature.

Bates, M.F., Branch, W.R., Bauer, A.M., Burger, M., Marais, J., Alexander, G.J. & de Villiers, M.S. (eds). 2014. (CD set). Atlas and Red List of the Reptiles of South Africa, Lesotho and Swaziland. Suricata 1. South African National Biodiversity Institute, Pretoria.

Marais, J. 2004. A Complete Guide to the Snakes of Southern Africa. Cape Town. STRUIK.

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