Alcedo Giant-Tortoise

Reptiles of Ecuador | Testudines | Testudinidae | Chelonoidis vandenburghi

Spanish common names: Galápago de Alcedo, tortuga gigante de Alcedo.

Recognition: ♂♂ 129 cm ♀♀ 89.7 cm. Chelonoidis vandenburghi is the only species of giant tortoise known to naturally occur on and around Alcedo Volcano on central Isabela Island. The species is recognizable by its domed carapace.

Natural history: Extremely common. Chelonoidis vandenburghi is a diurnal and terrestrial tortoise inhabiting evergreen forests, deciduous forests, and humid grasslands. Alcedo Giant-Tortoises spend most of the time feeding, resting on soil, or congregated in muddy rain pools.1 At night, they sleep out in the open.2 Their diet includes grasses, shrubs, sedges, forbs, leaves of trees, lichens, and fruits, including those from the strongly irritant manzanillo.1,3,4 The tortoises obtain water from their diet or from rain pools.1

Special thanks to Ellen Smith, our official protector of the Alcedo Giant-Tortoise, for symbolically adopting this species and helping bring the Reptiles of Galápagos project to life.

Males of Chelonoidis vandenburghi fight each other using a combination of biting, gaping, pushing, and neck extensions.5 When mating, they produce resounding guttural sounds.6 Females begin nesting between May and June at the end of the rainy season,1 and they lay 6–26 eggs in areas of soft soil.1 Not all of these hatch; some nests are destroyed by fungal infections during periods of high rainfall.7 Previously, before 2004, nests were lost due to trampling by feral donkeys.8 The hatchlings stay in warmer, lower elevation areas for their first 10–15 years.2 As adults, they are seasonal migrants, traveling up to 13 km in a matter of days.9 They travel for >25 km in a semi-circular path along the rim of Alcedo Volcano's caldera, and descend to the floor of the caldera or to the volcano's slopes to exploit new vegetation after the rains.10,11 Some Alcedo Giant-Tortoises die by falling from cliffs or by drowning during floods.7

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Conservation: Vulnerable.12 Chelonoidis vandenburghi is listed in this category because ~83% of the population disappeared in the last 180 years.12 Before human impact, the population is estimated to have been 38,000 animals.12 Now, about 6,320 individuals remain.12 Fortunately, these numbers are increasing following the eradication of exotic species (goats, pigs, and donkeys), which formerly either preyed on the eggs and the hatchlings, trampled nests, or destroyed tortoise habitat.12–14 Unlike other Galápagos tortoises, C. vandenburghi was probably never heavily exploited by whalers due to the inaccessibility of Alcedo Volcano; however, volcanic activity has produced major reductions of the C. vandenburghi population in recent times.15 The last major eruption of Alcedo was about 100,000 years ago16 and it is the most likely explanation for the low genetic diversity of the species.15 Other remaining threats for the recovery of the Alcedo Giant-Tortoise include predation of eggs and hatchlings by rodents, and the risk of the reintroduction of exotic species.12

Distribution: Chelonoidis vandenburghi is endemic to an estimated 476 km2 area on Alcedo Volcano. Galápagos, Ecuador.

Distribution of Chelonoidis vandenburghi Distribution of Chelonoidis vandenburghi in western Galápagos

Etymology: The generic name Chelonoidis comes from the Greek word chelone (meaning “tortoise”).17 The specific epithet vandenburghi honors John Van Denburgh (1872–1924),6 curator of herpetology at the California Academy of Sciences, in recognition of his invaluable work on Galápagos tortoises.

See it in the wild: Individuals of Chelonoidis vandenburghi can be seen with ~60% certainty at Urbina Bay, a coastal tourism site near the base of Alcedo Volcano in Isabela Island. However, the best place to see and photograph members of this species is in and around the caldera of Alcedo Volcano, which seasonally holds hundreds or even thousands of tortoises.

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: Alejandro ArteagaaAffiliation: Tropical Herping (TH), Quito, Ecuador. and Jose VieiraaAffiliation: Tropical Herping (TH), Quito, Ecuador.,eAffiliation: ExSitu, Quito, Ecuador.

How to cite? Arteaga A, Guayasamin JM (2020) Chelonoidis vandenburghi. 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. Fowler LE (1983) The population and feeding ecology of tortoises and feral burros on Volcán Alcedo, Galápagos Islands. PhD Thesis, Gainesville, United States, University of Florida.
  2. 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.
  3. Slevin JR (1935) An account of the reptiles inhabiting the Galápagos Islands. Bulletin of the New York Zoological Society 38: 3–24.
  4. 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.
  5. 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.
  6. DeSola CR (1930) The Liebespiel of Testudo vandenburghi, a new name for the mid-Albemarle Island Galápagos tortoise. Copeia 1930: 79–80.
  7. Márquez C, Wiedenfeld DA, Naranjo S, and Llerena W (2008) The 1997-8 El Niño and the Galápagos tortoises Geochelone vandenburghi on Alcedo Volcano, Galápagos. Galápagos Research 65: 7–10.
  8. Fowler de Neira LE, Roe JH (1984) Emergence success of tortoise nests and the effect of feral burros on nest success on Volcán Alcedo, Galápagos. Copeia 1984: 702–707.
  9. Bastille‐Rousseau G, Yackulic CB, Frair JL, Cabrera F, Blake S (2016) Allometric and temporal scaling of movement characteristics in Galápagos tortoises. Journal of Animal Ecology 85: 1171–1181.
  10. Bastille-Rousseau G, Gibbs JP, Yackulic CB, Frair JL, Cabrera F, Rousseau LP, Wikelski M, Kümmeth F, Blake S (2017) Animal movement in the absence of predation: environmental drivers of movement strategies in a partial migration system. Oikos 126: 1004–1019.
  11. Pritchard PCH (1996) The Galápagos tortoises. Nomenclatural and survival status. Chelonian Research Monographs 1: 1–85.
  12. Cayot LJ, Gibbs JP, Tapia W, Caccone A (2018) Chelonoidis vandenburghi. The IUCN Red List of threatened species. Available from: www.iucnredlist.org
  13. 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.
  14. Márquez C, Gibbs JP, Carrión V, Naranjo S, Llerena A (2012) Population response of giant Galápagos tortoises to feral goat removal. Restoration Ecology 21: 181–185.
  15. Beheregaray LB, Ciofi C, Geist D, Gibbs JP, Caccone A, Powell JR (2003) Genes record a prehistoric volcano eruption in the Galápagos. Science 302: 75.
  16. Geist D, Howard KA, Jellinek AM, Rayder S (1994) The volcanic history of Volcán Alcedo, Galápagos Archipelago: a case study of rhyolitic oceanic vulcanism. Bulletin of Vulcanology 56: 243–260.
  17. Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington, 882 pp.