Reptiles
Eyelash Viper
Bothriechis schlegelii · also called eyelash palm pit viper, eyelash pit viper
The eyelash viper is a small, jewel-coloured pit viper of Central and South American rainforest, instantly recognisable by the fringe of spiny scales over each eye. It lives its life among the branches, waiting in a tight coil for a frog, a lizard, or a hummingbird to come close enough to strike.
Overview
Eyelash vipers are arboreal snakes of lowland and cloud forest, from southern Mexico to the northern Andes. They spend the day coiled on vegetation a metre or two above the ground — on branches, vine tangles, and inside the leaf bases of palms, bromeliads, and heliconias, frequently near flowering plants and along streams where prey is abundant. They are nocturnal hunters and largely sedentary, sometimes staying on the same perch for days.
The eyelashes and the colours
Two features make this snake unmistakable:
- The “eyelashes” — a small crest of raised, pointed scales above each eye. Whether they mainly serve as camouflage, as eye protection while moving through wet leaves, or as rain guttering is still debated.
- Extreme colour variation. The same species appears in bright golden yellow, green, pink, brown, and grey, and different colour forms occur together. The golden “oropel” morph may act as a lure, resembling a flower or fruit.
Hunting
The eyelash viper is a classic ambush predator. It anchors itself with its prehensile tail, forms an S-shaped striking coil, and waits, reading the darkness with the heat-sensing pits on its face. When a warm-bodied animal — frog, anole, rodent, bat, or bird — comes within range, the snake strikes, injects venom, and often holds the prey until it stops moving. Eyelash vipers are notable for regularly catching hummingbirds at feeders and flowering shrubs.
Reproduction
Eyelash vipers are viviparous, giving birth to litters of roughly 6 to 20 fully formed, venomous young after a gestation of about six months. The neonates are independent immediately and, like the adults, can be any of the species’ colour forms.
Status and human contact
The eyelash viper is Least Concern and common. Because it perches at head and hand height on plantation crops, it is one of the snakes most often responsible for bites to farm workers — especially banana, plantain, and coffee harvesters — and to people who brush against or try to photograph it without noticing it. Bites are painful and can cause serious local damage, but antivenom is available and fatalities are uncommon. As a small forest species it also faces the general pressure of rainforest clearance, and it is collected for the exotic-pet trade for its striking colours.
Eyelash Viper: common questions
Why does the eyelash viper have "eyelashes"?
The bristly scales above each eye are the snake's most distinctive feature, but their purpose is not settled. The leading ideas are that they break up the outline of the head so the coiled snake looks more like a clump of moss or a bromeliad, that they shield the eyes as the snake pushes through wet foliage, or that they help channel water away from the eyes in the rainforest. They are not sensory, and not all individuals have them equally developed.
Why do eyelash vipers come in so many colours?
Bothriechis schlegelii is one of the most colour-variable snakes in the world. A single population — even a single litter — can include gold, lime green, olive, grey-brown, and pink individuals. The bright "oropel" (golden) form is thought to mimic a fallen flower or ripe fruit, luring in frogs and lizards, while the green and mottled forms are cryptic among leaves. Which colour an individual is appears to be genetically fixed for life.
How does an eyelash viper hunt?
By sit-and-wait ambush, usually a metre or two off the ground on a branch, vine, or the leaves of a palm or heliconia, often near a flower or a stream where prey concentrates. It anchors itself with its prehensile tail and hangs in an S-shaped coil, using its heat-sensing facial pits to detect warm animals in the dark, then strikes outward, holds the prey while the venom works, and swallows it. Eyelash vipers are among the few snakes regularly recorded catching hummingbirds.
How dangerous is an eyelash viper bite?
Serious but seldom lethal. The venom is mainly haemotoxic, causing intense local pain, swelling, blistering, tissue damage, and disturbed blood clotting; systemic bleeding can occur in bad cases. Because the snake is small and often sits at face and hand height on vegetation, bites to agricultural workers, especially banana and coffee pickers, and to careless hikers and photographers are relatively common in its range. Antivenom is effective, and deaths are rare with treatment.