Reproduction

KUBISCH, ERIKA; IBARGÜENGOYTÍA, NORA

Galapagos Giant Tortoises

Elsevier

Año: 2020; p. 157 - 171

The reproductive cycle of Galapagos tortoises has primarily been studied in captive individuals via non-invasive methodologies, including hormonal studies, radiographs, and ultrasound. During the annual reproductive cycle, mating peaks during the hot season months (December-June), followed by nesting during the cool season (June-December). Females dig flask-shaped holes in the soil typically in flat areas at lower elevations where soil suitable for digging accumulates. Females deposit 1- 26 eggs and close nests with a mixture of urine, feces, and soil, which then dries into a hard cap that seals in moisture and provides a protective layer for developing embryos. Rate of development and the sex of the embryos depend on the temperature of the nest: when incubation temperatures are high (above 29.5°C) embryos become female and when temperatures are low (below 28°C), they are male. Eggs hatch after 90-270 days of incubation and the young remain in the nest for up to one month until all eggs have hatched and they have consumed their yolk reserves. Hatchlings then dig an exit hole and emerge from the nest.