They are found in the Atlantic lowlands of eastern Mexico and Central American countries including Guatemala, Honduras, Belize, Nicaragua, Panama and Costa Rica. It's also found in the northern regions of South America, including Ecuador, Colombia and Venezuela. The fer-de-lance is the the only snake in the genus Bothrops found on the island of Trinidad.
Their prefered habitats include all moist environments located at low to middle elevations up to 2,000 ft (600 m) like tropical rainforests. But it can also be found in other habitats including lowlands to lower mountainous regions, thorn forest or pine savannah near to rivers, streams or lakes or in drier parts of tropical deciduous forests and Mexico's cloud forests.
The fer-de-lance or terciopelo can also be found at much higher elevations, for instance in Mexico and Central America its found anywhere from sea level up to to 3,900 to 4,300 ft (1,200 to 1,300 m). Although they tend to avoid drier areas with strong seasonal dry periods, adult specimens may be found in desert areas.
And in South America, it is found even at higher elevations up to 8,200 ft (2,500 m) in Venezuela and 8,660 ft (2,640 m) in Colombia. They will also readily occupy newly cleared land for agricultural areas or plantations.
It's a very adaptable species, capable of thriving in nearly all habitats, and for that it is one of the most abundant pit viper species in the world. The fer-de-lance is also very often found near human habitations, for this reason these snakes are considered even more dangerous to humans than other venomous snake species.
The common name fer-de-lance from the French, was originally used to refer to the Martinique lancehead (Bothrops lanceolatus) found on the island of Martinique in the West Indies.
But in North America the name fer-de-lance is often used to refer to snakes of the genus Bothrops, like the common lancehead (Bothrops atrox).
Strangely within the countries it inhabits the name fer-de-lance isn't used, these snakes are known by many other common names.
Among those common names are terciopelo (velvet in spanish), barba amarilla ("yellow beard") in Guatemala and Honduras, taya equis in Colombia, cuaima in Venezuela, equis in Ecuador and Panama and nauyaca in México. Probably the strangest name is "yellow-jawed tommygoff" or sometimes simply "Yellowjaw" or "Tommy Goff" used in Belize.
Like other snakes in the genus Bothrops the fer-de-lance as a broad, flattened head which very distinct from the body. The head is usually a medium to dark brown color but it can even be black, and sometimes have occipital blotches or streaks more or less distinct.
The fer-de-lance typically measures from 4 to 6 ft (1.2 to 1.8 m) in length and may weigh up to 13 pounds (6 kg). Females are much larger than males and have thicker and heavy bodies sometimes reaching up to 10 times the size of males.
Although no subspecies are currently recognized, they were formerly regarded as a subspecies of common lancehead (Bothrops atrox) and is many times still confused with it.
Venom / Bite
The fer-de-lance is the main cause of snakebite incidents within its range and bite symptoms include local pain, severe swelling, numbness, nausea, vomiting, blistering, bruising, and necrosis. They have a very potent and fast acting hemotoxic venom.
They are considered the most dangerous snake species in Costa Rica, responsible for almost half of all snakebites and 1/3 of all hospitalization cases. Many people are killed each year within its range by the fer-de-lance.
Douglas March a well-known herpetologist died after being bitten by a fer-de-lance. However even with its high venom yield and huge fangs (around 1 inch in large females) the species has a low mortality rate around 1 to 2%.
The specific antivenom is quite effective, but in many cases the tissue necrosis is quite severe and amputations are very common, those bitten end up losing limbs or parts of the extremities. Sometimes in parts of the body away from the bite site, for instance individuals bitten in the upper body sometimes may require a toe or even an entire foot amputation.
The fer-de-lance venom yield by dry weight averages around 458 mg, and as an intraperitoneal LD50 value in mice of 2.844 mg/kg. Recently researchers used a hydrogel infused with its venom, which injected into an open wound is able to shut down bleeding in mere seconds. There are also studies to use the venom to slow the onset of Alzheimer's disease.
Diet / Feeding
Their size and strength, combined with it's extremely toxic venom makes them highly effective predators. Due to the terciopelo vast distribution, its feeding habits include a wide range of prey.
The juvenile snakes feed mainly on small lizards or large insects like centipedes, while adults feed on mammals, amphibians, reptiles and even other snakes.
In Ecuador the fer-de-lance or terciopelo feeds primarily on rodents, while in the island of Trinidad they feed on almost everything from rodents, small mammals, lizards, frogs, birds and even crayfish.
In Costa Rica, adults have been known to feed on rats, opossums and other rodents, as well as rabbits, frogs and geckos.
These snakes are considered the most prolific in all of the Americas. The species reaches sexual maturity at 110 to 120 cm for females while males average at 100 cm.
The terciopelo or fer-de-lance breeding season takes place usually during the rainy season when food is also available. Since the terciopelo is found in a very large geographic range, the species reproduction habits and timing varies greatly. Sometimes females will store sperm enabling them to to delay fertilization.
For example in the Pacific region, they mate from September to November, and females give birth between April and June. While the Atlantic populations found in Costa Rica have the mating season in March and births between September and November.
The female's size determines the number of offspring produced. Females give birth to anywhere from 5 to 86 viviparous young after a gestation period of 6 to 8 months.
Conservation / Threats
The species is in decline in Ecuador due to deforestation, urbanization, agriculture and contamination. But they are a very adaptable species and are still found in open and suburban zones, although they aren't yet evaluated, it's regarded as a "Least Concern" species on the IUCN Red List.
In other parts of it's range like Costa Rica the human impact has been mostly positive, because the fer-de-lance is capable to thrive in agricultural environments like banana, cacao and coffee fields. Only when the changes to their environment are more drastic including diminishing prey there's a negative impact on population numbers.
Did You Know?
Capable of moving up to up to 20 km/h the black mamba snake is the world’s fastest snake.