Venomous Golden Lancehead Of Brazil's Snake Island: Why It Must Be Left Alone?

Aerial view of Queimada Grande Island, Brazil, one of the most dangerous places in the world due to the presence of the golden lancehead vipers.
Aerial view of Queimada Grande Island, Brazil, one of the most dangerous places in the world due to the presence of the golden lancehead vipers.

The Golden lancehead snake, scientifically known as Bothrops insularis is one of the most venomous snakes in the world. The snake is endemic to the Ilha de Queimada Grande Island, popularly known as Snake Island. The island, situated about 90 miles off the coast of the Brazilian state of Sao Paulo, covers an area of 110 acres. Snake Island consists of tropical and subtropical moist forests, shrubs, and open spaces. At first glance, the island seems like one of those tropical destinations everyone dreams about. However, the island is home to thousands of venomous snakes that inhabiting the island, making it one of the most dangerous places on earth. Golden lancehead snakes present on the island are also not safe on the island because they face threats from poachers, habitat degradation, and diseases. In the last 15 years, their population has declined by nearly 50% by some estimates. The species is currently listed as critically endangered by the International Union for Conservation of Nature. If urgent action is not taken, conservationists are concerned that the species, which is only found on the island, might be driven to extinction.

Importance Of The Golden Lancehead Snake

People using high-blood pressure medication often take captopril or its derivatives, a lifesaving drug that is developed from toxins obtained from the lancehead viper. According to Zoltan Takacs, founder of the World Toxin Bank, the use of snake venom in medicine, opened up a new class of medication known as ACE (angiotensin-converting enzyme) inhibitors, currently used to treat over 40 million people around the world. The approval of captopril by the FDA in 1981, helped push the idea that venoms could be used in the creation of modern medicine. Since then, venom based medicine has flourished. The boom has also prompted scientists from different parts of the world to seek out rare and venomous species of snakes in search of more potent drugs.

Golden Lancehead Snake Bites

Experts believe that a bite from the lancehead snake on a human carries a 7% chance of death. Even with treatment, humans still face a 3% chance of dying. Venom from the snake is likely to cause brain hemorrhaging, kidney failure, intestinal bleeding, and necrosis of muscular tissue. Lancehead viper venom is hemotoxic, which means that it destroys red blood cells, disrupts blood clotting, causes organ degeneration, and tissue damage. The venom thus helps digest the prey before the snake swallows it. The venom is also known to have neurotoxic properties, meaning that it can cause muscle paralysis, respiratory difficulty, and death. Chemical analysis of the snake’s venom indicates that it is five times more potent than that of its mainland cousin, Bothrops jararaca. The venom also acts faster than that of its cousins. Despite being one of the most venomous snakes in the world, there has never been a recorded snake bite on humans. There are, however, several legends about fatalities on the island. One such tale tells of a fisherman who strayed and decided to search for bananas on the island, his body was discovered days later in his boat, with snake bite marks on it. From 1909 to the 1920s, there were a few people who lived on the island to run its lighthouse. According to other local tales, the islands last lighthouse keeper and his entire family died after numerous snakes slithered through the windows of his home and attacked them. Operations at the lighthouse have since been automated and only require annual maintenance services from the Brazilian Navy. The island is also currently uninhabited, and adventure travel to the island is not allowed by the authorities. However, a few scientists are allowed on the island to study the snakes. The scientists also occasionally milk golden lancehead snakes for their venom, which is used in developing medication.


Golden lancehead snakes feed on perching migratory birds that stopover at the island and lizards. There are also incidents of cannibalism among the snakes. Golden lancehead newborns and younger snakes feed on invertebrates. Scientists believe that about 11,000 years ago, a rise in sea levels gradually separated the Ilha da Queimada Grande Island from mainland Brazil, leading to the isolation of the species. The snakes, therefore, evolved over thousands of years on a different path compared to their mainland cousins. A lack of ground predators meant that they reproduced rapidly. However, the only challenge was that the island also lacked ground prey. The snakes, therefore, slithered up the trees to hunt migratory birds. Golden lancehead snakes also evolved one of the most potent venoms in the world that kill prey almost instantly.

Poaching And Hunting

Golden lancehead snakes are in very high demand in the black market. Wealthy animal collectors from around the world are particularly interested in the species due to their uniqueness. Overzealous scientists, eager to make medical breakthroughs, also drive the high demand on the black market. The island is therefore frequented by wildlife smugglers keen to cash in on the lethal vipers. Experts estimate that a single golden lancehead snake can go for between $10,000 and $30,000, which is an attractive sum of money for the poachers. Research suggests that the illegal removal of individuals from the island could be a reason behind the decline of the golden lancehead population. Poaching is particularly harmful to the species since it targets the largest and thus the oldest individuals, which are also the most reproductively mature. Targeting such older snakes means that fewer snakes in the population reach old age classes leaving higher proportions of younger snakes. Studies also reveal that body size is usually positively related to fecundity, especially in female reptiles. A decline of older and larger individuals could, therefore, lead to a drop in average population fecundity, which negatively affects population growth. Similar trends are observed in the green python (Morelia viridis) populations in Oceania. Targeting adult females can, however, be advantageous when establishing colonies of captive-bred snakes.

Habitat Degradation Through Fires

In the past, fires have been deliberately started on the island in an attempt to eliminate the golden lancehead snakes so that acreage on the island can be utilized for plantation agriculture. The island’s name, Ilha da Queimada Grande, is a Portuguese title that loosely translates to Slash and Burn Fire or Big Burnt Island. The name refers to an attempt made by early developers to establish a banana plantation on the island through the slash and burn method, which is an environmentally destructive technique. Such activities likely led to the death of a significant population of snakes on the island. Numerous snakes on the island have eventually forced the developers to abandon their plans.

Habitat Destruction On Mainland Brazil

Conservationists are also concerned about habitat destruction on mainland Brazil. Although the snake island is miles away, many of the birds that arrive on the island (a primary source of food for the snakes) originate from mainland Brazil. The golden lancehead snake preys on two out of 41 migratory birds that seasonally arrive on the island. The tyrant flycatcher is the most common prey among adult pitvipers. The bird is found on the coast of southeastern Brazil towards the end of the wet season (austral summer). Low numbers of tyrant flycatcher birds making stops on the island in the corresponding season results in low survival rates of the snake population due to a scarcity of food. Prey availability also affects reproduction. Golden lancehead snakes have lower breeding frequency than the B. jararaca species found on the mainland, which enjoys relatively higher prey availability rates. The observation indicates that there is a close relationship between prey availability and population trends. Migratory birds, therefore, help maintain a delicate balance on the island’s ecosystem. Land clearing and the destruction of forests on mainland Brazil essentially robs migratory birds of their natural habitat leading to a decline in the bird population, which consequently affects the delicate balance on the island. Such human-made destructions have led to a steep decline in the number of migratory birds making stopovers on the island, which means less food for the snakes.

Habitat Destruction Through Vegetation Clearing

The Brazilian Navy has also been accused of destructive vegetation clearing around the lighthouse. Such activity negatively affects the habitat on the island, which consequently affects the snake population. Since the species is only found on the island, any alteration of its environment can have potentially devastating effects on the snake population.

Conservation Of The Species

Experts suggest that conservation of the golden lancehead’s habitat and the eradication of poaching are the most sustainable methods of saving the species. New innovative ideas are also being developed to help save the species. Artificial insemination is currently being researched by Rogerio Zacariotti, a conservation biologist, as a means of preserving the species. The technique has been successfully used to aid in the reproduction of other endangered species, but it has yet to be perfected in snake reproduction. The procedure, as done by Zacariotti, involves catching a live venomous snake, restraining it, and then massaging the sperm toward the exit where it is collected. The collected specimen is then used for future implantation.


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