How Tortoises Lay and Incubate Eggs, From Digging to Hatching

Have you ever wondered how tortoises lay eggs? For many temperate species, such as Mediterranean and North American tortoises, eggs typically hatch between late August and early October, though hatching times can vary by species and region. This video by TheTortoiseWhisperer shows a tortoise digging its burrow to lay the eggs in. If you’re curious to learn more, read below!

Tortoise Egg Preparation

After a female tortoise is fertilized, she undergoes several changes. After mating, the female tortoise will carry eggs for weeks to months, depending on the species. As the female tortoise gets closer to laying her eggs, her behavioral changes become more noticeable. These may include restlessness and digging test holes while searching for a suitable nesting spot. Female tortoises choose their nests for a few reasons. Sand or loose soil is ideal because it makes it easier for the mother to dig the nest and for the hatchlings to dig themselves out. Warm, dry sand or soil also helps with digging and incubation, creating the best conditions for the developing eggs.

When a suitable nesting spot is found, the tortoise will use its hind legs to dig the nest hole. The size and depth depend on the species and the individual tortoise, but are usually around four to ten inches deep. As seen in the video, the tortoise digs an extra chamber specifically for laying the eggs. The number of eggs laid in a clutch varies by species and age. Smaller tortoises will lay roughly five eggs, while bigger tortoises may lay up to 30 at a time. The eggs are laid one by one into the nest and are then covered by the mother to incubate and keep them safe. A tortoise may lay eggs one to three times a year if it is in good health, most often in spring to early summer when environmental conditions are ideal.

Gestation and Post-Laying

As the eggs are laid underground, the incubation period is in isolation without help from the mother. Incubation time depends on the species as well as the temperature. Warmer temperatures allow the eggs to incubate quickly, making the gestation period shorter. Generally, the incubation period lasts for 70–120 days, or roughly two and a half to four months. Temperature is important not only for determining incubation time, but also for determining the sex of the hatchlings. Warmer temperatures have higher chances of producing females, while lower temperatures more often produce males. This occurs because the temperature of the soil influences how the hatchlings’ gonads develop. In some species, temperatures below 82 degrees produce mostly males, while temperatures above 88 degrees produce females.

After laying a clutch, a tortoise mother’s job is mostly done. As the sand provides safety to the eggs, the mother leaves the nest and does not return. Tortoise mothers do not provide parental care after the eggs are laid. A female tortoise typically begins laying eggs between 10 and 20 years of age, with smaller species starting around 10 years and larger species up to 25 years. Other factors, such as diet and growth rate, also influence when a tortoise reaches sexual maturity. Tortoises can continue to lay eggs into old age. Generally, tortoises can lay eggs into their 50s or 60s, with rare cases of some individuals reproducing at older ages. Tortoises typically reproduce for a span of 30–50 years, depending on the species and individual health.