The name Bothriopsis bilineata comes from the Greek words "bothros" meaning "pit" and "-opsis" meaning "face", in reference to their facial pit organs. The epithet "bilineata" is derived from Latin. "Bi-" is a prefix for "two" and "lineatus" for "lined or marked with lines". This pertains to their ventrolateral yellow stripes. Other common names noted for the pitviper are green Tommy goffi, Cobra papagaio, lora, orito, and loro machaco.
Bothriopsis bilineata, like other pitvipers, has heat-sensing pits located between the eyes and nostrils, on both sides of the head. Within these pits are numerous heat-sensitive nerves that are covered by thin membranous tissue. The pits are highly vascularized, which helps maintain a constant temperature, thereby increasing sensitivity to changes in ambient temperature. In addition to heat-sensing pits, B. bilineata also has well-developed binocular vision resulting from its vertical slits. This trait, common to all pitvipers, increases depth and visual perception. Like all snakes, Bothriopsis bilineata has an adept olfactory perception.
Other than those that occur during mating season, little is known about intraspecific interactions in Bothriopsis bilineata. During mating season, male-male competition takes place. During these competitive interactions, two males become intertwined in an attempt to force one another to the ground. The winner gains access to mates and territory. Although they lack ears, snakes are highly sensitive to vibrations.
Communication Channels: visual ; tactile
Other Communication Modes: vibrations
Perception Channels: visual ; infrared/heat ; vibrations ; chemical
Bothriopsis bilineata has not been evaluated by the IUCN and is not currently listed on any threatened species lists. The greatest threat to this species is humans. Deforestation has been linked to population declines, and from 1988 to 2010, about 385,000 km^2 of primary habitat in the Amazon has been destroyed. While it is know that this species is distributed throughout lowland rain forests in the Amazon, Bolivia, Peru, Ecuador, Brazil, Venezuela, and the Guianas (elevations below 1,000 m, usually near waterways), little information is available about current population sizes. Its nocturnal activity and coloration make its numbers difficult to estimate. Because it is highly venomous, this species is often killed when encountered by human.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Bothriopsis bilineata is ovoviviparous, meaning that the eggs develop internally, with the mother giving birth to live young. Neonates are venomous upon birth and are known to be more aggressive at times than the adults. After birth, young feed upon frogs, lizards, and other relatively small prey. Individual size depends greatly on food availability. Adult females are typically larger than adult males.
Bothriopsis bilineata is potentially dangerous, as a single strike from this snake releases extremely toxic venom. Their venom is contains pro-coagulant and anticoagulant agents and their bite can result in severe hemorrhaging. Bothriopsis bilineata has been reported to be the second most dangerous snake in the Amazon, behind only Bothrops atrox. Numerous accounts of bites have been documented, some resulting in death. In studies of snake bite cases near Columbia, about 15% of bites were from B. bilineata. Bleeding from the gums, site of bite, and orifices often occur after a bite. Other related symptoms include hematemesis, hematuria, loss of consciousness, erythema, headaches, pain at envenomation site, tissue necrosis, and edema. Bothriopsis bilineata is not considered an aggressive species, but has been known to strike when disturbed. Because this is an arboreal species, most bites reported are to the hands, arms, and face.
Negative Impacts: injures humans (bites or stings, venomous )
In the past, the venom of Bothriopsis bilineata has been the subject of research for its anticoagulation properties; however, locating this species is reportedly very challenging. Therefore, not a great deal of research has been conducted on this species.
Positive Impacts: research and education
Bothriopsis bilineata are predators of many species of small birds, frogs, and lizards in their ecosystem. They are highly venomous and are probably avoided by most species throughout their geographic range. Parasites of this species are unknown.
Two-striped forest pitvipers are nocturnal predators. They rest in trees and shrubs 3 to 4 feet above the ground and use their heat-sensing pits to generate a thermal picture of the surrounding environment and potential prey. Evidence suggests that they occasionally use their tails as a lure to attract prey. These vipers prey mainly on frogs, but also regularly eat small birds. Recently, stomach content analysis has revealed that two-striped forest pitvipers also feed on a variety of lizards and small mammals, including mice and rabbits.
Animal Foods: birds; mammals; amphibians; reptiles
Primary Diet: carnivore (Eats terrestrial vertebrates)
Bothriopsis bilineata is found in the South American neotropics. The largest populations are found in the Amazonian regions of Bolivia, Columbia, Equador, Peru, and Brazil. Other highly populated regions include equatorial forests of Venezuela, Guyana, French Guiana, and Suriname. It is most abundant in southwest South America, in Parque Nacional. Bothriopsis bilineata has been documented as far south as Jacarepagua, which is located within the city limits of Rio de Janeiro. However, the species was removed from Jacarepagua in 1963 and is now considered rare in that region.
Biogeographic Regions: neotropical (Native )
Two-striped forest-pitvipers are present only in forested habitats. Its distribution ranges from sea level to approximately 1000 m in elevation. They very seldom are found at elevations above 1000 m. Their most common habitat is wet lowland rainforests, where they live primarily near waterways, especially along streams. Two-striped forest-pitvipers spend much of their time on branches and shrubs more than 1 m off the ground. While they are particularly abundant in very wet primary forests, these snakes also occur in secondary forests near or adjacent to primary forests. Wet lowland rainforests occupied by two-striped forest-pitvipers usually have a canopy height of 40 m, but individual trees can reach up to 65 m. However, trees in wet lowland rainforests typically have a greater height, height to first branch, trunk volume, buttress height and buttress area than in other rainforest ecosystems. Sub-canopy vegetation in lowland rainforests primarily consists of successional trees rather than shrubs or herbs.
Range elevation: 0 to 1000 m.
Habitat Regions: tropical
Terrestrial Biomes: forest ; rainforest
Other Habitat Features: riparian
There is no information on the average lifespan of Bothriopsis bilineata. In general, estimated lifespan for pitvipers ranges from 10 to 25 years, with variations most likely due to captivity. One account describes a B. bilineata that lived in the Dallas Zoo for 13 years, after being received by the zoo as an adult.
Bothriopsis bilineata is a sleek, green pitviper with a prehensile tail. Typical length is about 70 cm, although individuals up to 123 cm have been reported. Females are usually 10 to 20 cm longer than males. In both sexes, the head is typically green with black spots, but sometimes may be green with tan or red spots with black margins. The iris of the eye is light green to yellow and the pupil is vertically elliptical. The tongue is pinkish-grey with dark grey tips. Snout length in B. bilineata is similar to that of other pit vipers, with a well defined canthus rostralis. Body coloration of in B. bilineata is pale green with black, red, or tan spots, on the dorsum. The enlarged scales on venter, commonly referred to as ventrals, are yellow with a green tinged bordering. A creamy yellow line borders the lateral margins of the ventrals and runs the entire length of the snake. The distal portion of the tail is pink outlined by yellow. Individuals with a whitish-yellow tail tip have been reported.
The two-striped forest pitviper are primarily arboreal. They weigh less and are a notably shorter in length than other species of pitviper. This difference in length has been attributed both to their arboreal habitat and feeding behavior. Smaller body size allows them to articulate through the dense shrubbery of the Amazon region.
Other characteristic features of Bothriopsis bilineata include 5 to 9 keeled intersupraoculars, 7 to 9 supralabials, 8 to 12 infralabials, and 23 to 25 midbody scale rows. Males have 190 to 218 ventrals and 65 to 76 mostly divided subcaudals, whereas females have 192 to 220 ventrals and 55 to 73 mostly divided subcaudals. Usually B. bilineata has a lacunolabial that is formed by the second supralabial and prelacunal fused together. However, sometimes present are partial or full sutures that separate these scales forming the lacunolabial. Members of the genus Bothriopsis have unique skull morphology in that the frontal bones are concave and are longer than than they are wide. The postfrontals do not contact the frontal bones and are long and narrow. All pitvipers have 5 palatine teeth, 14 to 18 pterygoid teeth, and 15 to 17 dentary teeth. Their maxillary fangs are around 1.5 to 2 times longer than the height of the maxillary bone.
Related or similar species to Bothriopsis bilineata includes subspecies B. b. smaragdinus, which differs in that it does not possess tan or red spots on its body. Rather, it is peppered only with black spots. One other prehensile-tailed pitviper in South America that might be confused with B. bilineata is Bothriechis schlegelii, which has white or yellow lines. However, sympatry between Bothriopsis bilineata and Bothriechis schlegelii has not been confirmed. In Ecuador, Peru, and Bolivia, there are four other green pitvipers. These include Bothriopsis pulchra, B. pulchra, B. peruviana, and B. oligolepsis. All of these species lack the paraventral stripes found in B. bilineata.
Range length: 57.3 to 123 cm.
Average length: <70cm cm.
Other Physical Features: heterothermic ; venomous
Sexual Dimorphism: female larger
Neotropical birds of prey tend to feed on venomous snakes, but because two-striped forest pitvipers are nocturnal and well-camouflaged, little is known about their predators. Birds of prey known to feed on venomous snakes in the Amazon include laughing falcons, crane hawks, roadside hawks, and swallow-tailed kites.
Anti-predator Adaptations: cryptic
There is no information available regarding the mating system of Bothriopsis bilineata. However, a study of Bothriopsis bilineata at the Dallas Zoo found that, during mating, males position themselves on one side of the female, while moving across her dorsum. While moving, the male makes very jerky motions and a hemipenis into the female’s cloaca. The male flicks his tongue extremely fast, approximately 43 to 71 times a minute. During this study, females gave birth in June, July, and October, with clutches ranging in size from 7 to 12 offspring. In many pitvipers, male-male competition, known as "the dance of the adders", takes places during the mating season and is mainly preformed to guard access to mates. Some reports suggest that this behavior may also be used to compete for territories. Fighting between males is done by holding the face and forebody erect and wrapping their bodies around one another as they attempt to force one another to the ground. Competitive bouts between males can take hours and usually ends with the winner gaining access a nearby female for mating.
Bothriopsis bilineata is ovoviviparous, meaning that the eggs develop internally, with the mother giving birth to live young. Clutch size ranges from 6 to 16 young. Neonates range in length from 20 to 26 cm and range in mass from 7 to 11 g, with an average of 10 g. Although little information is known concerning the reproductive behavior of Bothriopsis bilineata, reproductive behavior of northern temperate pitvipers is thought to be very similar. Reproductive cycle begins with spermatogenesis and vitellogenesis. Vitellogenesis in females usually occurs during late summer or fall with the development of follicles pausing during winter and resuming during spring. Courtship and mating generally occurs during late summer to winter, from April to October. Long-term sperm storage may be used during the winter, from July to September, and is essential in many pitvipers. Delaying fertilization makes it possible for birthing to occur during a favorable time of year and likely increases offspring survival. During spring, ovulation, fertilization and embryogenesis take place. Birth most likely occurs during the rainy season of summer, which is usually in March. However, this cycle likely varies in relation to weather, food availability and by species.
Range number of offspring: 4 to 16.
Average number of offspring: 9.
Key Reproductive Features: seasonal breeding ; sexual ; fertilization ; ovoviviparous ; sperm-storing ; delayed fertilization
Bothriopsis bilineata females store sperm until the optimal time to fertilize the eggs. Once the eggs are fertilized, the mother carries the embryos until the eggs are ready to hatch, which occurs internally. For all pitvipers, young venomous upon birth and are able to hunt. Some mothers stay with the young for 7 to 10 days. However, young are typically independent upon birth.
Parental Investment: pre-hatching/birth (Provisioning: Female)
