The Eyelash Viper, Bothriechis schlegelii, is a small, venomous pit viper known for the modified scales above its eyes that give it a distinctive, bristly appearance. This arboreal snake makes its home in the tropical rainforests and cloud forests of Central and South America, ranging from southern Mexico down to Ecuador and Venezuela. Its life in the trees significantly shapes its diet, relying on a strategy of camouflage and patience to capture prey in the forest canopy.
The Primary Diet of Adult Eyelash Vipers
The diet of a mature Eyelash Viper is highly varied, consisting mostly of small vertebrates found in the trees and shrubs. Birds, especially nesting birds and their young, are a main food source. Studies show that the vipers sometimes position themselves near migratory pathways, suggesting an awareness of seasonal bird movements. They have even been observed striking quickly enough to capture hovering hummingbirds.
Small mammals, such as mice, bats, and mouse opossums, also make up a large portion of their meals. Because the vipers are often active at night, they are well-positioned to ambush nocturnal prey like bats that visit fruit trees. The snake’s heat-sensing pit organs help it locate these warm-blooded animals even in complete darkness.
The adult viper’s diet is opportunistic, and it also consumes cold-blooded prey. Lizards (anoles and geckos) and various species of treefrogs are regular parts of their diet. Their preference for prey found in elevated vegetation distinguishes them from many ground-dwelling vipers.
Ontogenetic Diet Shift: Juvenile Versus Adult Prey
Eyelash Vipers exhibit a significant change in diet as they grow, a phenomenon known as ontogenetic diet shift. Newborn vipers are much smaller, which limits the size and type of prey they can successfully subdue. This size constraint means that young snakes rely heavily on smaller, cold-blooded animals.
The primary food for juvenile Eyelash Vipers is small frogs, followed by tiny lizards. Because these smaller prey items are often found closer to the forest floor, young vipers may spend slightly more time at lower elevations than their adult counterparts. As the snake matures, its gape and venom capacity develop, allowing it to transition to the larger, warm-blooded prey that dominates the adult diet.
Hunting Techniques and Ambush Strategy
The Eyelash Viper is a classic sit-and-wait predator, relying on exceptional camouflage. The snake will choose a promising perch, often near a known food source like a fruit or flower that attracts smaller animals, and remain motionless for extended periods. This ambush strategy conserves energy while maximizing the chance of a successful strike.
Their specialized anatomy helps them maintain this position; the prehensile tail is used to anchor securely to branches and vines. When a potential meal comes within range, the viper executes a swift and decisive strike, injecting hemotoxic venom that quickly incapacitates the prey. After the strike, the viper waits for the venom to take effect before consuming the animal whole.
Juvenile vipers often employ a specialized hunting behavior called caudal luring. The young snake wiggles its brightly colored tail tip (yellow or green) in a worm-like motion. This movement acts as a lure, attracting small frogs and lizards into striking distance. This technique helps the smaller snake secure the cold-blooded prey necessary for its early development.