Bothrops asper

The range of Bothrops colombiensis includes the northwestern coast of South America from Ecuador to Venezuela, Trinidad, and north as far as Mexico. More specifically, in Mexico and Central America Bothrops colombiensis is found north to the Southern Tamaulipas and south to the Southeastern Yucatan Peninsula. It dwells in the lowland Atlantic coastal areas of Nicaragua, Costa Rica, and Panama. Terciopelos (Bothrops colombiensis) are also found in the northern areas of both Guatamala and Honduras. (Campbell and Lamar, 2004; O'Shea, 2005; Sasa, et al., 2009)

In South America these vipers are typically found west and north of the Andes, though there are exceptions, most notably in Venezuela where it can be found in the San Cristobal and Barquiseto Depressions in the Southeast region of the country. Bothrops colombiensis is found on the Pacfic coastal plains and Andes Pacific versant from Columbia to as far south as the border of Peru and Ecuador. These snakes are also found in Northern Peru near the Pacific coast. In Columbia their range extends from the Pacific to the Carribean coastal plain as well as deeper within the country in the valleys of the Andes. Bothrops colombiensis lives in sympatry with Bothrops atrox in central northern Columbia and certain areas of Venezuela. Bothrops atrox typically ranges further south in the Amazonian countries, but due to its similar appearance and overlapping distribution of Bothrops colombiensis the snakes are often mistaken for one another. To further confusion, Bothrops colombiensis was once considered a subspecies of B. atrox. (Campbell and Lamar, 2004; Sasa, et al., 2009)

Bothrops colombiensis is primarily found in the tropical rainforest, the tropical evergreen forest, and the outer edge of savannas, but has also been found in a wide variety of other habitats including lowland and lower mountainous regions, dry regions of some tropical deciduous forests, and the cloud forests of Mexico. Bothrops colombiensis prefers higher levels of humidity but adults may be found in desert areas as they are at less risk for dehydration than their juvenile counterparts. In Ecuador, Terciopelos inhabit the low montane wet and dry forests as well as the coastal cloud forests. Bothrops colombiensis is known to move in to newly cleared agricultural land areas in many countries as well as the forested uplands in Trinidad. These vipers are mainly terrestrial, but some juveniles are known to climb trees. They have been documented at elevations from sea level to 2,640 m above sea level. (Campbell and Lamar, 2004; Cisneros-Heredia and Touzet, 2004; O'Shea, 2005)

Members of the genus Bothrops are distinguished by their broad, flattened heads which are set apart from the rest of the body. Their eye lids (canthus) are very distinct. In drier regions, terciopelos have more scales to prevent water loss. Bothrops colombiensis varies greatly phenotypically across its geographic range. This has led to the confusion between it and other species, most notably Bothrops atrox, which is similar in color but often contains yellow or rust like tones and rectangular or trapezoidal blotches. The head of Bothrops colombiensis is medium to dark brown or even black. It may have occipital botches or streaks that range from indistinct to distinct, but usually are absent. The underside is most often pale yellow. Individuals may weigh up to 6 kg and typically measure 1.2 to 1.8 m in length. (Campbell and Lamar, 2004; O'Shea, 2005; Saldarriaga-Córdoba, et al., 2009; United States Navy, 1962)

Like most other Bothrops, B. asper has different patterns and colors on its dorsal and ventral sides and also exhibits a postorbital stripe. The ventral side is yellow, cream, or a whitish gray, with dark blotches (mottling) that increases in frequency towards the posterior end. Ventrolaterally, the viper has alternating dark gray scales which are paler towards the medial line. Dorsally, the viper is olive, gray, brown, grayish brown, tan or at times nearly black. It has dark triangles with pale edges laterally, which range in number from 18 to 25. Apices either alternate or are reflective of each other over the middorsal line. In the interspaces, there are dark, paravertebral blotches. An individual may have a yellow zig-zag shaped line on each side of the body. (Campbell and Lamar, 2004)

Terciopelos exhibit great sexual dimorphism. From birth, males are notably smaller in size than females. Females have thick, heavy bodies and can reach up to 10 times the size of males. Males have 161 to 216 ventral scales and 57 to 81 subcaudals. Females have 187 to 240 ventrals and 46 to 70 subcaudals. Juvenile females have a brown tail tip while males have a yellow tail tip. Prior to sexual maturation, males completely lose their yellow tip. (Campbell and Lamar, 2004; Sasa, et al., 2009)

Bothrops colombiensis is viviparous, making development to the neonatal/juvenile state internal. (Campbell and Lamar, 2004; Sasa, et al., 2009; Solórzano and Cerdas, 1989)

Unlike many vipers, there are no documented cases of male-male combat in Bothrops colombiensis. Often females will mate with more than one male in a mating season. Mating includes a series of movements of the male who then slowly chases an accepting female. He often bobs his head at her side. The female then stops movement and extends her posture to mate. It is not known whether this species exhibits annual or biennial reproduction. (Sasa, et al., 2009; Solórzano and Cerdas, 1989)

Bothrops colombiensis is considered the most prolific snake in all of the Americas. It breeds seasonally, usually during the rainy season when food is readily available. Males are known to follow females during the mating season in some regions. Fertilization is internal. Because terciopelos have a large geographic range, the time and length of reproduction varies greatly. For instance, in the Atlantic population of Costa Rica, B. asper mates in March, but in the Pacific region, it mates from September to November. This variation continues throughout Central and South America. There is a positive correlation between the body size of the female parent and the number of offspring she produces. After a gestation period of 6 to 8 months, females give birth to 5 to 86 viviparous young. These young terciopelos weigh between 6.1 and 20.2 grams each. There is also some evidence of long term sperm storage by the females to delay fertilization. Females are 110 to 120 cm at sexual maturity, while males average at 99.5 cm. (Campbell and Lamar, 2004; Sasa, et al., 2009; Solórzano and Cerdas, 1989)

Females build up fat stores which lead to a release in hormones that stimulate ovulation. Females gestate for 6 to 8 months before giving birth to live young. There is no parental care.

Recapture of the species is uncommon, so longevity in the wild is unknown. However, it is estimated that lifespan in the wild is similar to that in captivity, which ranges from 15 to 21 years based on zoo-keeping records. (Bowler, 1977; Sasa, et al., 2009)

Like much of Bothrops, B. asper is a nocturnal, solitary species. Activity varies seasonally, with B. asper becoming less active in colder and dryer months. Terciopelos are most often found near river and stream banks, basking in the sun during the day and under forest cover ready to ambush during the night. The viper also exhibits an S-coiled defense display when threatened by another species. Juveniles are known to climb trees and also to exhibit caudal luring, a use of their different colored tail tips to lure prey. (Campbell and Lamar, 2004; Sasa, et al., 2009)

Because B. asper is highly sedentary, ambushing to capture prey, the viper usually does not stray more than 1200 m over a two-night period and maintains a much smaller activity center than its home range. Terciopelos only leave this activity center in the absence of food or sufficient humidity. They have an estimated territory range of 37,100 m. (Sasa, et al., 2009)

Communication and perception is not well studied in Bothrops colombiensis. However, the species is named for its loreal heat-sensing pit which it uses at night to detect prey. Males follow females to show they are interested in mating, and will exhibit head-bobbing motions if the female allows him to approach.

Like all snakes, Bothrops colombiensis perceives its environment through visual, infrared, tactile, and chemical stimuli. (Campbell and Lamar, 2004; Sasa, et al., 2009)

Bothrops colombiensis, due to its vast distribution, feeds on a wide variety of prey. The size, strength, and extremely toxic venom make terciopelos effective predators. In adult years, they have been known to feed on mammals, amphibians, and reptiles, but are not limited to these groups. Juveniles feed on small lizards and even large insects such as Scolopendra angulata.

In Costa Rica, adults have been known to feed on rats (Rattus rattus), opossums (Caluromys derbianus and Didelphis marsupialis), and other rodents, as well as rabbits (Sylvilagus brasiliensis), frogs (Lithobates forreri) and geckos (Gonatodes albogularis). In Ecuador they primarily feed on rodents. On the island of Trinidad, Bothrops colombiensis has been known to feed on everything from rodents and other small mammals, lizards, frogs and birds, or even crayfish. These species include Didelphis marsupialis and Ninia atrata. (Campbell and Lamar, 2004)

Though well camouflaged, large, and venomous Bothrops colombiensis has many predators, notably mussuranas (Clelia clelia). Mussuranas are snakes known to use their own venom and constrictive abilities to prey on other snakes. The blood of Clelia clelia contains an inhibitor of some the powerful toxins of the venom of terciopelos. Raptors, such as laughing falcons (Herpetotheres cacchinans), swallow-tailed kites (Elanoides forficatus), and crane hawks (Geranospiza caerulescens) are also important predators of terciopelos. The most effective are laughing falcons which can successfully defeat incredibly large female terciopelos. (Campbell and Lamar, 2004)

Those less effective predators which can only feed on small to medium-sized terciopelos include mammalian predators such as hog-nosed skunks (Conepatus leuconotus), raccoons (Procyon lotor), and coatis Nasua nasua and Nasua narica. The more susceptible juveniles are preyed upon by many smaller raptors including roadside hawks (Buteo magnirostris). Some crabs, the spider Phoneutria, and tarantulas are suspected to prey on neonates. (Sasa, et al., 2009)

Bothrops colombiensis has many parasites. Internal parasites include the nematodes Filaria, Rhabdias vellardi, Kalicephalus inermes, trematodes (Ochetosoma genus), and flatworms (Acanthocephala). Parasitic protozoans include hemogregarianes as well as amoeba and amoeba-like organisms. These have been known to cause gastroenteritis and hepatitis, among other illnesses. External parasites include several ticks, including Amblyoma savanae and Amblyoma dissimile, a known vector of hemogregarianes. (Sasa, et al., 2009)

Terciopelos serve as prey to many species, and likely play a role in supporting local populations. Mussuranas, as well as many raptors including laughing falcons (Herpetotheres cacchinans), swallow-tailed kites (Elanoides forficatus), and crane hawks (Geranospiza caerulescens) prey upon terciopelos. Predators that prey on small terciopelos include mammalian predators such as hog-nosed skunks (Conepatus leuconotus), the coatis Nasua nasua and Nasua narica and racoons (Procyon lotor). Juveniles are preyed upon by many smaller raptors including roadside hawks (Buteo magnirostris). Some crabs and tarantulas prey on neonates. (Campbell and Lamar, 2004)

Bothrops colombiensis are also important predators in their ecosystems and thus impact local populations of prey species as well. Juveniles feed on small lizards and even large insects such as Scolopendra angulata. Adults feed on rats (Rattus rattus), opossums (Caluromys derbianus and Didelphis marsupialis), and other rodents, as well as rabbits (Sylviagus brasiliensis), frogs (Lithobates forreri) and geckos (Gonatodes albogularis). (Sasa, et al., 2009)

Terciopelos feed on small rats and other seed eaters which are detrimental to farmers. The venom has potential pharmacological implications and continues to be of promise. (Sasa, et al., 2009)

Bothrops colombiensis is responsible for the most deaths by venomous snakes in most of its geographic range. Often living close to humans in lowland areas and having highly-toxic venom results in a significant impact in the areas it inhabits. Its well studied venom is hemorrhagic, myonecrotic and proteolytic. It can cause incredible pain, necrosis of the region, and progressive edema. (Campbell and Lamar, 2004)

Urbanization, deforestation, contamination, and agriculture have resulted in the declining number of Bothrops colombiensis in Ecuador. In spite of this, some are able to live and even thrive in open and suburban zones. It has been suggested that the Ecuadorian B. asper be placed as a species of "Least Concern" on the IUCN Redlist, though the species is currently not evaluated. (Cisneros-Heredia and Touzet, 2004)

In Costa Rica, human impact has seemed to favor Bothrops colombiensis. Terciopelos have been able to prosper in certain agricultural fields such as banana, cacao and coffee. Even though they are adaptable, some areas have seen a decline which is thought to stem from more drastic environmental changes and decline of prey. (Sasa, et al., 2009)

Common Names: Terciopelos, barbas amarillas, fer de lance, cola de hueso, rabo de hueso, cola blanca, yellow-jaw tommygoff, cuatronarices, equis, cachete de punica, cascabelle, among many others. (Campbell and Lamar, 2004; Sasa, et al., 2009)