Ilha da Queimada Grande

Ilha da Queimada Grande, also known as Snake Island, is an island off the coast of Brazil in the Atlantic Ocean. It is administered as part of the municipality of Itanhaém in the State of São Paulo. The island is small in size, only 43 hectares (106 acres), and has a temperate climate. The island's terrain varies considerably, ranging from bare rock to rainforest.

Ilha da Queimada Grande
Nickname: Snake Island
Aerial view of Ilha da Queimada Grande
Ilha da Queimada Grande
Location of Ilha da Queimada Grande in Brazil
Geography
LocationAtlantic Ocean
Coordinates24°29′10″S 46°40′30″W
Area430,000 m2 (4,600,000 sq ft)
Highest elevation206 m (676 ft)
Administration
StateState of São Paulo
MunicipalityItanhaém
Administered byChico Mendes Institute for Biodiversity Conservation (ICMBio)
Demographics
Population0

The island is the only 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 when rising sea levels covered up the land that connected it to the mainland. The ensuing selection pressure allowed the snakes to adapt to their new environment, increasing rapidly in population and rendering the island dangerous to public visitation.

Queimada Grande is closed to the public in order to protect both people and the snake population; access is only available to the Brazilian Navy and selected researchers vetted by the Chico Mendes Institute for Biodiversity Conservation, the Brazilian federal conservation unit.[1][2][3]

Geography

Located approximately 33 kilometres (21 mi) off the coast of the state of São Paulo, Brazil, the island is approximately 430,000 square metres (110 acres) in area. The island ranges in elevation from sea level to 206 metres (676 ft) above sea level. The island has a temperate climate that is similar to its neighbouring island Nimer. 0.25 square kilometres (62 acres) of the island is covered by rain forest; the remaining areas consist of barren rocks and open grassland. Queimada Grande ranges from an average of 18.38 °C (65.08 °F) in August to 27.28 °C (81.10 °F) in March, and rainfall ranges from 0.2 millimetres (0.0079 in) per month in July to 135.2 millimetres (5.32 in) in December.[1][4]

History

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", in Portuguese, means “burnt” because when locals attempted to clear land for a banana plantation on the island, they had to clear rain forest using this technique. 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.[5][6][7]

The island and the Ilha Queimada Pequena to the west are protected by the 33 hectares (82 acres) Ilhas Queimada Pequena e Queimada Grande Area of Relevant Ecological Interest, created in 1985.[8] The Brazilian Navy has closed the island to the public[9] and the only people who are allowed on the island are research teams who receive waivers to collect data.

Endangerment

Because there are so many snakes on one island, by some estimates one snake to every square meter (10.8 square feet) of the island, there is competition for resources. Despite a population of 41 recorded bird species on Queimada Grande, the golden lancehead relies on only two: the Troglodytes musculus (the southern house wren), which is usually able to avoid the golden lancehead as a predator, and the Chilean elaenia (a species of flycatcher), which feeds on vegetation in the same area as the snake.

The island was 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 population to be 2,000 to 4,000, concentrated almost entirely in the rainforest area of the island.[10][11] 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.[5] The Bothrops insularis also may be at risk from inbreeding, effects of which are evident in the population.

Because of 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.[1][11]

See also

References
  1. Marques, Otavio A. V.; Kasperoviczus, Karina; Almeida-Santos, Selma M. (2013). "Reproductive Ecology of the Threatened Pitviper Bothrops insularis from Queimada Grande Island, Southeast Brazil". Journal of Herpetology. 47 (3): 393–399. doi:10.1670/11-267. ISSN 0022-1511.
  2. Thomas, Emily (July 4, 2014). "Brazil's 'Snake Island' Is The Place Of Nightmares, We're Pretty Sure". Huff Post Science. TheHuffingtonPost. Retrieved October 24, 2015.
  3. "Exposição traz história da ilha que abriga única espécie de cobra no mundo" (DOC) (in Portuguese). Secretaria De Comunicação Social, Prefeitura Municipal De Itanhaém. 2007. Retrieved 2016-09-20.
  4. Cox, Savannah (December 17, 2012). "Four Tiny Islands That You'll Never Visit". all-that-is-interesting. PBH network. Retrieved November 4, 2015.
  5. Channel, Discovery. "Treasure Quest: Snake Island Facts".
  6. A. V. Marques, Otavio; Martins, Marcio; Sazima, Ivan (2002). "A jararaca da ilha da Queimada Grande" (PDF). Ciência Hoje (in Portuguese). Sociedade Brasileira para o Progresso da Ciência. 31 (2): 56–59. Retrieved 8 August 2015.
  7. Snake Island Part 1, Vice
  8. ARIE das Ilhas Queimada Pequena e Queimada Grande (in Portuguese), ISA: Instituto Socioambiental, retrieved 2016-11-20
  9. "Snake Island - Ilha da Queimada Grande". AtlasObsura. Atlas Obscura. November 11, 2015. Retrieved October 28, 2015.
  10. Martins, Marcio; Sawaya, Ricardo J.; Marques, Otavio A. V. (2008). "A First Estimate of the Population Size of the Critically Endangered Lancehead, Bothrops insularis". South American Journal of Herpetology. 3 (2): 168–174. doi:10.2994/1808-9798(2008)3[168:AFEOTP]2.0.CO;2. ISSN 1808-9798.
  11. Marques, Otavio A. V.; Martins, Marcio; Develey, Pedro F.; Macarrão, Arthur; Sazima, Ivan (2012). "The golden lanceheadBothrops insularis(Serpentes: Viperidae) relies on two seasonally plentiful bird species visiting its island habitat". Journal of Natural History. 46 (13–14): 885–895. doi:10.1080/00222933.2011.654278. ISSN 0022-2933.
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