Fer-de-lances are the most abundant venomous snake in Central America, and probably also part of South America they inhabit. They are certainly common in Trinidad, where they are called mapepire balsain. They are ambush hunters (see the section herein entitled “Feeding Ecology of Bothrops asper . . .”), and rely totally on their superb camouflage dorsal pattern accompanied by their stealth. Although we occasionally encounter them coiled on or near trails during the day, they tend to be more alert (and dangerous to humans) when hunting at night. Males are smaller and thinner than the 6-8 foot females, and their bites thus are armed with less venom.
In general, venomous snakes that are biting their prey or potential predators pull their necks back in a coil, then are capable of striking the length of the coils’ length of the body. We warn that this length may be a bit longer if the animal is touching a surface that it can use to enhance its lunge forward during the strike. We’ve seen an interesting variation on these facts in that smaller fer-de-lances, maybe up to 18 inches in length, have the ability during a strike to launch 6 inches or so off the ground. This jump can cause problems for an observer who doesn’t anticipate this launch of a venomous attack!
Stories abound about people stepping very near them with the snake remaining very still. In Trinidad we see juveniles off the ground on stems and leaves, and we assume they do the same farther north.
Current studies are trying to understand the relationships of the snakes we used to simply call fer-de-lance.
Generally the fer-de-lance that lives in Central America and some western coastal areas of South America are understood to be Bothrops asper, with B. atrox being more of a Trinidadian and mainland northern South America species. The valued Reptile Database suggests some differences. There will soon be a more thorough understanding of relationships and distribution of these marvelous snakes