Male mating behavior (Schafer 1982; Bonin et al. 2006, and as noted)
Female mating behavior
Egg description (de Vries 1984; Bonin et al. 2006, except as noted)
Causes of mortality (MacFarland et al. 1974; de Vries 1984; Elizabeth A. Hunter, personal communication, 2016)
Diseases and parasites (non-comprehensive list)
In 1958, the San Diego Zoo had its first success in hatching Giant Galápagos Tortoise eggs. Here, reptile keeper Jerry Staedeli examines a nest.
Reptile curator Charles Shaw had the insight to provide females with a nesting area made of river-bottom sand instead of dirt. Just two months later, six clutches of eggs were laid!
For years, the San Diego Zoo housed the only breeding colony among zoos, worldwide.
Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.