Fer-de-lances (Bothrops atrox) are one of the largest and most deadly snakes of Central and South America. They are Costa Rica's most feared snake and with good reason: 50% of all snakebites are from this venomous viper. Described as the ultimate pit-viper, fer-de-lances are excitable, unpredictable and can deliver swift and aggressive strikes. With up to 90 live young born in a single brood, they are a common cause of snakebites in their range. During the day, fer-de-lance lie coiled amongst the leaf-litter, where their long, thick bodies can be hard to spot. Come sundown, the search begins for something to eat.