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Galapagos Giant Tortoises (Chelonoidis spp.) Fact Sheet: Diet & Feeding

Diet & Feeding

  • Little known (Blake et al. 2015a)
    • Only a few in-depth studies
  • Broad diet of leaves, stems, and fruits (Schafer 1982; Gibbs et al. 2010; Gibbs et al. 2014; Blake et al. 2015a)
    • Grasses
    • Woody shrubs
    • Stone fruits (drupes)
    • Prickly pear cactus (Opuntia)
      • Source of food, water, and shade
      • Pads grow high (arboreal form) to reduce tortoise and land iguana grazing
  • May seek out plants with high water content, especially when water is scarce (Cayot 1987)
  • Drink large amounts of water, if available (Swingland 1989)
  • Will drink from water collecting in rock depressions
  • Long periods of inactivity during harsh conditions (Bonin et al. 2006; Orenstein 2012)
    • Make sojourns to water sources
  • Can go weeks or months without food or water (de Vries 1984; Bonin et al. 2006)
    • Water generated from metabolism of stored fat
      • Build up fat reserves when vegetation is plentiful
      • Able to survive droughts
    • Enables dispersal from island to island
  • Diet study of two Santa Cruz species (Blake et al. 2015a)
    • Giant Galápagos Tortoises consumed more than 60 plant species in 20 families
      • Seeds of many species eaten
    • Ate many introduced, non-native plants and seeds (Blake et al. 2015a)
      • May represent changes in diet since the 1930s-1950s
        • Human removal of native plants for agriculture began at this time
      • Exhibited healthier body condition
  • Advantage provided by elevated carapaces of saddle-backed tortoises (Blake et al. 2015a)
    • Thought to have evolved in order to reach Opuntia (prickly pear cactus) and other high-growing plants
  • Some observations of eating meat, though rare (Bonin et al. 2006)
    • Birds
    • Dead goats

The Best Eating Is Up High

Galapagos tortoise reaches high for cactus

Cacti on some Galápagos Islands grow like small trees to stay out of reach of hungry tortoises.

The raised opening of the saddle-backed tortoises' shell likely evolved to counter this cactus defense.

The raised opening also helps saddle-backed tortoises compete while stretching their necks during dominance interactions.

Image credit: © Frank J. Sulloway. All rights reserved. Used with permission from the artist; image found here.

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