Cerro Azul Giant-Tortoise

Reptiles of Ecuador | Testudines | Testudinidae | Chelonoidis vicina

English common names: Cerro Azul Giant-Tortoise, Iguana Cove Giant-Tortoise.

Spanish common names: Galápago de Cerro Azul, tortuga gigante de Cerro Azul.

Recognition: ♂♂ 117.1 cm ♀♀ 93 cm. Chelonoidis vicina is a giant tortoise having a domed carapace form. It is generally the only species of giant tortoise known to naturally occur around Cerro Azul Volcano. However, there are some places where it can be found living side by side with C. guntheri, a species in which some adult individuals have a distinctive dorsally-flattened carapace. With the exception of these individuals with a flattened carapace, tortoises of the two species may be indistinguishable without the use of genetic information.

Natural history: Common. Chelonoidis vicina is a diurnal and terrestrial tortoise that inhabits deciduous forests, evergreen forests, and dry grasslands. Cerro Azul Giant-Tortoises spend most of the daytime feeding or moving.1 During the hot afternoon hours, they rest in the shade or wallow in mud or in damp soil.1 Their diet includes grasses, leaves of trees, cacti, lichens, and berries, including those from the strongly irritant manzanillo.15 Males fight with each other using a combination of biting, gaping, neck extensions, and shell-bumping.6 When mating, the tortoises produce resounding guttural sounds. Females of C. vicina lay their eggs on soft soil.1 Juveniles of the Cerro Azul Giant-Tortoise stay in warmer lowland areas for their first 10–15 years of life.7 As adults, they migrate from inland to coastal areas along well-established trails to forage on new vegetation after the rains.1 Eggs and neonates of C. vicina are preyed upon by introduced pigs and fire ants, as well as trampled by feral cattle.7,8

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Conservation: Endangered.9 It is estimated that 97–98% of the population of Chelonoidis vicina disappeared in the last 180 years.9,10 The number of Cerro Azul Giant Tortoises declined catastrophically from about 18,000 individuals before human impact down to an estimated 400–600 in the 1970s.9,10 Causes of the population decline, some of which are ongoing, include extensive overexploitation for food by sailors (mostly whalers) and settlers1,7 and the introduction of exotic species (including goats, pigs, dogs, rodents, and fire ants), which either prey on tortoise eggs and hatchlings or destroy their habitat.7,8,11

To this day, the recovery of Chelonoidis vicina remains restrained.9 Pigs and ants continue to decimate nests, feral cattle trample nests and compete with the tortoises for resources, introduced vegetation degrades natural habitats and interferes with migratory routes, and illegal slaughter and poaching of tortoises still occurs.9 Another threat faced by C. vicina is volcanic eruptions, which cause direct mortality and destroy and fragment tortoise habitat.9 Today, only four populations of the Cerro Azul Giant-Tortoise remain in the wild.12 These account for a total of about 1,800–2,700 animals,9 but the actual number of purebred individuals may be much lower.12 Whether these numbers are increasing is unknown. Some of the positive conservation actions carried out by the Galápagos National Park include the eradication of goats and the establishment of a head-starting program at the Centro de Crianza Arnaldo Tupiza, in which young tortoises are raised in captivity and subsequently released into the wild.9

Distribution: Chelonoidis vicina is endemic to an estimated 254 km2 area on Cerro Azul Volcano. Galápagos, Ecuador.

Distribution of Chelonoidis vicina Distribution of Chelonoidis vicina in western Galápagos

Etymology: The generic name Chelonoidis comes from the Greek word chelone (meaning “tortoise”).13 The specific epithet vicina comes from the Latin word vicinus (meaning “neighboring”) and is probably14 a reference to the distribution of this species, which is adjacent to the distribution of C. guntheri.

See it in the wild: The few remaining populations of purebred Chelonoidis vicina occur on and around Cerro Azul Volcano, which is inaccessible to tourism. Researchers and members of the Galápagos National Park may visit the habitat of C. vicina, but only in the context of a scientific expedition or a conservation agenda. Head-started juveniles of C. vicina can be seen at the Centro de Crianza Arnaldo Tupiza in Isabela Island.

Special thanks to Kerri Murphy for symbolically adopting the Cerro Azul Giant-Tortoise and helping bring the Reptiles of Ecuador book project to life.

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Authors: Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador. and Juan M GuayasaminbAffiliation: Laboratorio de Biología Evolutiva, Universidad San Francisco de Quito (USFQ), Quito, Ecuador.,cAffiliation: Galapagos Science Center, Galápagos, Ecuador.,dAffiliation: Centro de Investigación de la Biodiversidad y Cambio Climático, Universidad Tecnológica Indoamérica, Quito, Ecuador.

Academic reviewers: Adalgisa Caccone.

Photographers: Jose VieiraaAffiliation: Tropical Herping (TH), Quito, Ecuador.,eAffiliation: ExSitu, Quito, Ecuador.

How to cite? Arteaga A, Guayasamin JM (2020) Chelonoidis vicina. In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: www.reptilesofecuador.com

Literature cited:

  1. Heller E (1903) Papers from the Hopkins-Stanford Galápagos Expedition, 1898-1899. XIV. Reptiles. Proceedings of the Washington Academy of Sciences 5:39–98.
  2. Darwin CR (1845) Journal of researches into the natural history and geology of the countries visited during the voyage of H.M.S. Beagle round the world, under the command of Capt. Fitz-Roy, R.N. John Murray, London, 519 pp.
  3. Daggett FS (1915) A Galápagos tortoise. Science 42: 933–934.
  4. Slevin JR (1935) An account of the reptiles inhabiting the Galápagos Islands. Bulletin of the New York Zoological Society 38: 3–24.
  5. Fritts TH, Fritts PR (1982) Race with extinction: herpetological notes of J. R. Slevin's journey to the Galápagos 1905–1906. Herpetological Monographs 1: 1–98.
  6. Schafer SF, Krekorian CO (1983) Agonistic behavior of the Galápagos tortoise, Geochelone elephantopus, with emphasis on its relationship to saddle-backed shell shape. Herpetologica 39: 448–456.
  7. Swingland IR (1989) Geochelone elephantopus. Galápagos giant tortoises. In: Swingland IR, Klemens MW (Eds) The conservation biology of tortoises. Occasional Papers of the IUCN Species Survival Commission (SSC), Gland, 24–28.
  8. Márquez C, Wiedenfeld D, Snell H, Fritts T, MacFarland C, Tapia W, Naranjo S (2004) Estado actual de las poblaciones de tortugas terrestres gigantes (Geochelone spp., Chelonia: Testudinidae) en las islas Galápagos. Ecología Aplicada 3: 98–111.
  9. Cayot LJ, Gibbs JP, Tapia W, Caccone A (2018) Chelonoidis vicina. The IUCN Red List of threatened species. Available from: www.iucnredlist.org
  10. MacFarland CG, Villa J, Toro B (1974) The Galápagos giant tortoises (Geochelone elephantopus). Part I: Status of the surviving populations. Biological Conservation 6: 118–133.
  11. Pritchard PCH (1996) The Galápagos tortoises. Nomenclatural and survival status. Chelonian Research Monographs 1: 1–85.
  12. Edwards DL, Garrick RC, Tapia W, Caccone A (2014) Cryptic structure and niche divergence within threatened Galápagos giant tortoises from southern Isabela Island. Conservation Genetics 15: 1357–1369.
  13. Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington, 882 pp.
  14. Van Denburgh J (1914) The gigantic land tortoises of the Galápagos Archipelago. Proceedings of the California Academy of Sciences 4: 203–374.