Twig Snake

The twig snake is a slender, highly arboreal colubrid found across savanna, woodland, and thicket habitats of sub-Saharan Africa. Its common name reflects its remarkable resemblance to a thin dead branch or vine, an appearance enhanced by its habit of remaining motionless with only its forked tongue flicking.

Despite belonging to the colubrid family, which contains mostly harmless species, the twig snake is a rear-fanged (opisthoglyphous) snake with a venom capable of causing serious, sometimes fatal, hemotoxic effects in humans. It is considered one of the more medically significant rear-fanged snakes in Africa, though bites to people are uncommon because the species is shy, slow-moving, and reluctant to bite unless provoked.

• Extremely thin, elongated body resembling a twig or vine
• Coloration is mottled gray, brown, and green with lichen-like blotching that provides camouflage against bark
• Head is narrow and elongated with a pointed snout
• Eyes have distinctive horizontal, keyhole-shaped pupils, unusual among snakes
• Scales are smooth to weakly keeled
• When threatened, it inflates its neck to reveal bright red or pink skin between the scales

This unusual pupil shape and neck-inflation display readily separate it from true vine snakes (Oxybelis) of the New World and from harmless twig-mimicking colubrids elsewhere.

Twig snakes inhabit savanna woodland, riverine forest edges, and thicket vegetation across much of sub-Saharan Africa, from East Africa southward through Zambia, Zimbabwe, Mozambique, and into South Africa. They are almost entirely arboreal, spending most of their time coiled motionless among branches, shrubs, and vine tangles, rarely descending to the ground except to move between trees.

Active by day, twig snakes are ambush predators that rely on camouflage to approach or wait for prey, which consists mainly of tree-dwelling lizards such as chameleons and agamas, as well as frogs and occasionally birds and their nestlings. When disturbed, an individual will inflate its throat, displaying bright interstitial skin, and may sway slowly to mimic a branch in the wind. The species is oviparous, with females laying small clutches of elongated eggs in tree hollows or leaf litter during the warmer months.