| 1 | Reaches 20 metres above ground |
The Bothrops pitviper genus is Brazil and South America’s signature venomous snake group, including such nightmares as the common lancehead and jararaca. Some roam dark riverside forests, while others inhabit lush grassy fields, but out of the 40-45 members, the one most restricted to rainforests is Bothrops bilineatus, AKA the green jararaca.
This species is widespread in South America, inhabiting a vast swathe of Brazil, as well as Colombia, Venezuela, eastern Ecuador and eastern Peru. The green jararaca almost completely sticks to primary and secondary rainforests, making occasional appearances in cocoa plantations directly adjacent to forests as well. It’s an almost fully nocturnal species, and is most commonly spotted resting on tree branches, while barely moving.
The green jararaca is not just the greenest, but the strongest climber of the Bothrops pitviper group. The likes of B. insularis and B. taeniatus also climb trees, but the green jararaca reaches the most towering, death-defying heights. In a 2021 study from the Lower Moa river forest of Acre state, Brazil, several green jararacas climbed to 10 metres above ground, and one to 20 metres. These weren’t mere exploratory missions, as they waited in the canopies for several days in order to ambush frogs.
The same study found an average resting branch height of 6.4 metres, while a 2019 study observed a green jararaca perch itself at 9.4 metres above ground for 3 days straight. At the time, this was considered to be a record, but it only took 2 years to be defeated by the 2021 study.
| 2 | Rarely found outside forests |
Despite being an ambush predator, Bothrops bilineatus isn’t as lazy as the emerald tree boa. The more active individuals will change position every 24 hours, sometimes moving to a new branch, sometimes to a new tree.
Adult green jararacas rest on branches, while juveniles are light enough to rest on thick leaves. They’re helped by a flexible, prehensile tail with strong gripping abilities. Within rainforests, they tend to appear in areas with streams nearby, as these form breeding grounds for their frog prey.
In Brazil, the feared common lancehead (Bothrops atrox) is most commonly encountered during wet and warm months. The green jararaca is the opposite, meeting humans most frequently during the dry season. When skies are overcast, forest trails are flooded, and leaves are dripping with water, they completely disappear. One study conducted from December to March failed to locate a single snake. Dry season is when they descend from their 10 metre high perches, which is conversely because humidity levels fall more rapidly higher up, and the ground retains more moisture.
| 3 | Hotspot: acai berry trees |
One of Brazil’s top health food exports is the small, black acai berry, which is hailed for its supposedly miraculous antioxidant properties. Acai berries are said to far outstrip red grapes for restoring health, but little do their fans realise that farmers are constantly having to dodge green jararacas in order to get them.
As well as high tree canopies, the green jararaca rests on branches closer to the ground as well, and the acai palm (Euterpe precatoria) is one of its favourites. Another favourite plant is the para passiava (Leopoldinia piassaba).
In some locations in South America, Bothrops bilineatus causes the 2nd highest snakebite total. These dangerous hotspots include Cruzeiro do Sul, Brazil, and Leticia, Columba. Most bites happen while slashing new forest trails, or harvesting rainforest resources. The disguise is so total than when resting 1 metre above ground, most villagers completely miss them, until they’re within breathing distance and it’s already too late.
In two recorded bites from Acre State, Brazil, berry harvesters were bitten 4 and 8 metres in the air, as they climbed high up acai palms and unwittingly disturbed lurking snakes. You only have to brush against one with your shoulder to activate its defensive response. In some regions, green jararacas cause as little as 3% of snakebites, but in others, they cause up to 36%.
| 4 | Scorching bite wounds |
The green jararaca’s venom has a relatively weak LD50 rating of 6.24mg, versus 0.46mg for a jararacussu. Deaths are relatively rare, but the bite cause unending local chaos: redness, swelling and intense pain. The one symptom that constantly appears in medical logs is heat, that the puncture marks become fiery hot. There’s severe swelling, accompanied by burning sensations, although there’s relatively little necrosis.
The main internal symptom is spontaneous bleeding, including from the gums, eyes, nose and of course bite mark. At least 1 death is on the records, and patients have produced brown-black urine before due to an attack on the kidneys.
American explorer William Beebe had a nasty encounter with this snake, reported in 1946. He walked within 1 foot of a green jararaca, resting 5 feet high on a bush. It struck towards his face, but as he crouched below a bush, it harmlessly struck the rim of his hat instead. Beebe then broke its back with the barrel of his gun. Because of their cosy branch perches, the majority of green jararaca victims are bitten on the chest, shoulders or hands.
| 5 | Green with subtle black edges |
Some of the Bothrops family snakes blend together, but Bothrops bilineatus is easy to recognise. It’s much thinner and greener than the others, particularly the whip-like tail. This snake isn’t particularly long, averaging at 73cm. The all time records were 123cm and 120cm, found in Venezuela. In a study from Acre State Brazil, the longest female observed was 75.8cm while the longest male reached 66.8cm. Females are longer than males in almost all Bothrops snakes.
This is clearly a green snake, but up close, it’s more subtle, as each green scale is bordered by black. The green jararaca has yellow irises with a green tinge, with vertical pupils. Its tongue is pinkish grey, with a dark grey tip, which is visible as it flecks around searching keenly for frog scents. Some green jararacas have red coloured spots on their sides, which the western subspecies B. bilineatus smaragdinus lacks. Others have black spots on their head, but the vivid forest green is always in place. Their belly is a yellow colour, with green tinges around the edges.
| 6 | Tempts prey with a pink tail |
The most obvious exception to the greenness is this snake’s white or even bright pink tail. This probably mystified early machete-wielding explorers, but the tail is actually a cunning hunting strategy: caudal luring. From its branch perch, the green jararaca will move its bright tail up and down its coiled body, wriggling the thin end in a sinuous fashion. The goal is to lure in frogs by imitating a worm or insect. Frogs are highly reliant on visuals, and the pinkness will stand out in a jungle environment.
Many snakes worldwide use caudal luring, but the green jararaca ranks first within the Bothrops pitviper genus. Other Amazon pitvipers like B. jararaca and B. moojeni use the technique as juveniles, but lose the tail colouring in adulthood. Bothrops bilineatus keeps the pinkness its entire life. They even use caudal luring when there’s no prey nearby, probably because the jungle is so thick, and it’s trying to flush out hiding prey it hasn’t noticed.
Height isn’t a question here, as one study observed green jararacas perched from 0.3 metres to 17.97 metres. This tricksy caudal luring was observed at all heights. The snakes clearly felt secure on even the most towering branches; they didn’t get unnerved and shift their focus more towards balancing.
| 7 | Grabs frogs from branches |
After lunging from their branches in ambush, the green jararaca always holds onto its prey tightly while the venom takes effect, rather than releasing and watching. 50% of its diet consists of amphibians, particularly frogs:
Marmorea frog (Dendropsophus marmoratus) – widespread across the Amazon. Feeds on beetles and ants. Likes to sit in pools on the forest floor and sing in choirs, but also found 20 metres high on branches.
Red snouted treefrog (Scinax ruber) – an extremely common South American frog, which has also invaded Puerto Rico. This light brown frog has beige eyes and can lay up to 590 eggs at once. It also lives beyond the Amazon in forest clearings and public parks.
Osteocephalus taurinus – a poisonous frog which produces the heart-stopping bufotenin. Lays up to 2000 black eggs, in a film that lies on ponds. Often seen on tree trunks and branches. Widespread, found in Peru, Ecuador, Brazil and more.
These three frogs live mainly on branches themselves, in a micro branch universe where the green jararaca is the ultimate antagonist. This is also a bat-eating snake, confirmed to munch on silky fruit-eating bats (Carollia brevicauda). A confirmed lizard prey is Gonatodes humeralis.
| 8 | Difficult to predict |
The strange thing about the green jararaca is how unpredictable it is. Sometimes you can walk into a forested grove, with all the box-ticking shallow streams and high towering canopies in place, yet not find one snake. It doesn’t obey the rules assigned to it by the neat categorisation of science.
There’s a large swathe of the Amazon where green jararacas are relatively rare. In a collection of 4 studies from different regions of Brazil, they only made up 0.16 to 1.34% of snake sightings. Yet a study from the lower Moa river, Acre State, found that it was the single most common snake, making up 28.46% of sightings. The green jararaca is also completely missing from Manaus region (north of the Amazon river) for no apparent reason, despite being in the centre of its range.
Anyone hunting for this snake could be severely disappointed, or hit the jackpot – there’s no way to tell. Being nocturnal and extremely green, it’s difficult to find them deliberately anyway.
| 9 | No specific antivenom |
Brazil has several antivenoms for dealing snakebites, but not one made using green jararaca venom. Bothrops AV is one three staples stocked by hospitals, alongside Bothrops-Lachesis AV and Lachesis AV (made from South American bushmasters). Bothrops AV is made from 5 species: 50% Bothrops jararaca (a monstrous snake), with the remaining 50% divided between b. neuwiedi . b. moojeni. b. jararacussu, and b. alternatus. As usual, the venoms are injected into hyperimmune horses, which produce extractable antibodies in response.
So are green jararaca victims alone, with no-one coming to help? Fortunately not, because all Bothrops species have a large crossover in toxins.
A study on 68 b. bilineatus victims found that standard Bothrops antivenom had a high success rate anyway. A bite victim from 2007 was stabilised with the antivenin, restricted to swelling, with no haemorrhaging. This victim had the usual fiery red wound, as according to the doctor: “the burning sensation was for real, the entire left arm was much hotter than the rest of the body“.
| 10 | Two subspecies (but possible four) |
The Bothrops name is the snake’s wider family, but bilineatus refers to the patterns on its flanks. Lineatus means “striped with lines”, while bi means two.
Officially, this tree snake is divided into two subspecies: Bothrops bilineatus bilineatus, and Bothrops bilineatus smaragdinus. The first occupies eastern Brazil, plus an isolated enclave in Brazil’s Atlantic forest, a forest fuelled by the Atlantic ocean which is totally separate from the Amazon. B .b. smaragdinus is the western subspecies, occupying western Brazil, Peru, Venezuela, and Columbia. Both favour dense, branchy forests. The main difference is physical; B. b bilineatus has red or yellowish spots over the green, while B. b. smaragdinus has small black spots.
Recently though, DNA analysis has questioned the old 2 subspecies belief. It concluded that the green jararaca is divided into 4 genetic clades with chasms between them: 1) Atlantic Forest 2) Guiana Shield 3) Western Amazon; and 4) Central Amazon. The first had a closer relationship, but the western and central clades were distant. It’s possible that Bothrops bilineatus is really three, possibly four subspecies. The limit of the western Amazon clade was the Orinoco river, while the central clade was found south of the Amazon river in Brazilian states such as Amazonas, Rondônia, Mato Grosso.