How to Identify the Mount Kenya Bush Viper (Identification Guide)

Key identifying features

The Mount Kenya Bush Viper (Atheris desaixi) is a rare, localized arboreal viper distinguished by strongly keeled scales, a stocky body, and a coloration adapted to the cool, mossy montane forests it inhabits. Its combination of rough scalation and restricted high-altitude range makes it identifiable once habitat and scale texture are considered together.

Coloration & pattern

Base color is typically dark olive, greenish-black, or blackish, often overlaid with yellow, orange, or greenish scale flecking that creates a somewhat mottled or speckled appearance rather than clean bands. Some individuals show more vivid yellow-green highlights concentrated along the flanks. The belly is generally a duller olive or grayish tone with faint mottling. Overall the pattern is cryptic, helping the snake blend against moss-covered branches and dark forest substrates.

Head, eyes & scales

The head is broad and triangular, clearly distinct from the neck, a hallmark of viper anatomy. Eyes are large with vertical pupils, aiding nocturnal hunting. Scales across the body are keeled, giving a rough, slightly bristly texture, though less extreme than the very spiny Atheris hispida. This roughness plus the flattened, wide head shape are key tactile and visual clues.

Size & body shape

This is a small-to-medium viper, usually reaching around 55-70 cm (22-28 inches) in total length. The body is moderately stocky for an arboreal viper, with a prehensile tail used for gripping branches and vines as it moves through vegetation.

Range & habitat where you'll see it

As its name suggests, this species is restricted to a very small range around Mount Kenya and the nearby Nyambene Hills in central Kenya, at relatively high elevations within montane and highland forest. It is arboreal, typically found coiled in shrubs, tangled vegetation, or low tree branches in cool, humid, high-altitude forest habitat — a much narrower range than most other bush vipers.

How to tell it apart from look-alikes

Other Atheris species overlap somewhat in general appearance, but the Mount Kenya Bush Viper's extremely restricted, high-elevation Kenyan range immediately narrows identification, since few other bush vipers occur there. Its scales are keeled but not as extravagantly spiny as the Spiny Bush Viper, and its coloration tends toward darker olive-black with scattered yellow-green flecks rather than the more uniform green of some lowland relatives.