Galapagos Giant Tortoises (Chelonoidis spp.) Fact Sheet: 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

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.