Galapagos Giant Tortoises (Chelonoidis spp.) Fact Sheet: Distribution & Habitat

Galápagos Giant Tortoises

• 1600s-early 1800s
• Abundant on the Galápagos Islands (MacFarland et al. 1974)
• Estimates of up to 300,000 tortoises (Linda Cayot citing James Gibbs' unpublished data, personal communication, 2016)
• Once found on at least nine Galápagos Islands (Edwards et al. 2014)
• Human-caused extinctions on a few islands
• Some human-mediated reintroductions beginning in 2010s (Cayot 2015a)

Giant tortoises (all species)

• Once widespread on all continents, except Antarctica (Powell and Caccone 2006; Hansen et al. 2010; Blake et al. 2015a)
• Until the late Pleistocene, < 1.8 mya
• “…extant giant tortoises are not island oddities, but rather the last examples of a once widespread lineage” (Blake et al. 2015a)
• Once common on islands in the Indian and Pacific Oceans (McDougal 2000; Standford 2010; Blake et al. 2015a)
• Overhunting by humans was main driver of their extinction
• Only surviving giant tortoises
• Galápagos and Aldrabra Giant Tortoises (near Seychelles, Indian Ocean)
• Not particularly closely related (Powell and Caccone 2006)
• Independently evolved gigantism (Powell and Caccone 2006)

Galápagos Giant Tortoises (GGTs)

• Approximately 20-25,000 GGTs in the wild (Cayot 2015a; galapagos.org)
• Recent reintroductions to islands where GGTs were driven to extinction (Cayot 2015a)
• Now, about 9-10 islands with GGTs
• Most major islands with a single GGT species (Poulakakis et al. 2012)
• Isabela and Santa Cruz have more than one species
• Elevation range
• Adults: 0-429 m (0-1,407 ft) (Blake et al. 2015a)
• Juveniles remain in lowlands; not found at high elevations (Blake et al. 2013)

(Poulakakis et al. 2012; Blake et al. 2015a; UNESCO.org  c1992-2016, except as noted)

• Chain of volcanic, oceanic islands
  • Never been connected to mainland South America
• 960 km (597 mi) west of Ecuador
• 129 islands, islets, and rocks
  • Official names for 13 large (over 1 km²) islands, 6 smaller islands, and over 40 islets
• Approximately 8,000 km² (3,088 mi²) of land over 45,000 km² (17,375 mi²) of ocean
• Volcanic activity is ongoing (Caccone et al. 1999)
• Climate
  • Hot, wet season: January to May
  • Cool and dry the rest of the year
• Oldest islands
  • San Cristóbal: emerged ~4 mya
  • Española: emerged ~3.5 mya
• Younger islands to the west
  • Youngest island: Fernandina
    • Began forming less than 70,000 years ago
• Four islands inhabited by humans (National Census of Ecuador, 2010; Orenstein 2012)
  • Human population: 25,000-30,000
  • Santa Cruz
  • San Cristóbal
  • Isabela
  • Floreana
• 1535: First record of humans visiting the islands
  • Fray Tomás de Berlanga, Bishop of Panama, names the islands “Galápagos”
    • From galapagos (Bonin et al. 2006)
      • Old Spanish word for chelonians (turtles and tortoises)
• 1959: Terrestrial areas declared a National Park
• 1978: Named a UNESCO World Heritage Site
• 1986: Galápagos Marine Reserve created
• Also see History

• Varies with species
• Humid uplands (Bastille-Rousseau et al. 2016)
• Lots of grass and vegetation
• Moist, volcanic craters (Bonin et al. 2006)
• Arid lowlands (Bastille-Rousseau et al. 2016)
• Dry, grassy or dry, rocky areas (Bonin et al. 2006)
• GGTs prefer areas of high cactus density, where cactus is available (Gibbs et al. 2014)
• Avoid woody plants, which limit movements

Giant Galápagos tortoise distribution.

Adapted from www.d-maps.com.
Click here or on map for detailed distribution from Wikipedia.