This might feel wierd, but it is true. We all know about many islands where civilisation existed or even today people living with no outer world connection, but this particular island is habitat to thousands of snakes.
Ilha da Queimada Grande, also known as Snake Island, is a small island that lies off the coast of the southeastern portion of Brazil. The land is part of the State of Sao Paulo, and it’s noteworthy for having several different terrains, including a small portion of the rainforest. Snake Island is simply littered with snakes, and they’re not just small constrictors.
Snake Island in Brazil is about 20 miles from the mainland coast, far enough away that the snakes can’t reach continental South America. The island is small, with an area of only 43 hectares, and has a temperate climate. Its terrain varies from bare rock to rainforest.
The island is the only natural home of the critically endangered, venomous Bothrops insularis (golden lancehead pit viper), which has a diet of birds.
The snakes became trapped on the island thousands of years ago following the end of the last ice age when rising ocean levels disconnected the island from the mainland. The ensuing evolutionary pressure allowed the snakes to adapt to their new environment, increasing rapidly in population and rendering the island dangerous to public visitation.
Ilha da Queimada Grande has a variety of vegetation. The island is partly covered in rainforest and partly bare rock and grassy cleared areas, a result of deforestation. The deforestation is the origin of the island’s name: the term queimada is Portuguese for forest fire: locals attempted to clear land for a banana plantation on the island by burning. A lighthouse was constructed in 1909 to steer ships away from the island. The last human inhabitants left the island when the lighthouse was automated.
As there are so many snakes on one island — by some estimates one snake to every square metre.
The island was previously thought to have a population of about 430,000 snakes, but recent estimates are much lower. The first systematic study of the population of the golden lancehead found the number to be 2,000 to 4,000, concentrated almost entirely in the rainforest area of the island. This might have happened because there was a limited amount of resources and the population became level, but in 2015 an estimate by a herpetologist on a Discovery Channel documentary stated that the population remains at 2,000 to 4,000 golden lanceheads. The golden lancehead also may be at risk from inbreeding, effects of which are evident in the population.
As the overall low population of the golden lancehead, the snake was labelled critically endangered on the IUCN Red List of Threatened Species. It also was placed on the list of Brazil’s endangered animals. The island is also home to a smaller population of Dipsas albifrons, a non-venomous snake species.
The Brazilian Navy has closed the island to the public to protect human and snake life. The only people who are allowed on the island are research teams who receive waivers to collect data.