Sea turtles undertake remarkable journeys to their nesting grounds. Their nesting behavior involves returning to sandy beaches to deposit their eggs.
How Many Eggs in a Single Nest
A female sea turtle lays a group of eggs in a single nest, called a clutch. The number of eggs within a clutch varies significantly among different species. For instance, Loggerhead sea turtles lay between 80 to 120 eggs per nest. Green sea turtles also lay a comparable number, averaging around 110 eggs per clutch, though some can lay up to 238 eggs.
Hawksbill sea turtles lay some of the largest clutches, often containing 140 to 160 eggs, and sometimes exceeding 200. In contrast, Leatherback sea turtles, despite being the largest sea turtle species, lay 70 to 90 yolked eggs per nest, along with a variable number of smaller, infertile eggs. Kemp’s Ridley and Olive Ridley turtles generally lay around 100 to 130 eggs per clutch.
The female digs a body pit with her front flippers, then uses her rear flippers to excavate a deeper, flask-shaped egg chamber. Once ready, she lays her soft-shelled, ping-pong ball-sized eggs. After depositing eggs, she covers the chamber with sand using her hind flippers and camouflages the nest by scattering sand with her front flippers before returning to the sea.
Laying Multiple Nests
Female sea turtles do not lay just one nest per season; they deposit multiple clutches. Most species lay between two to seven clutches within a single nesting season. For example, Loggerhead turtles can lay 2 to 5 clutches, while Leatherbacks lay 4 to 7. Hawksbills also lay between 3 to 6 clutches per season.
The interval between these nesting events ranges from 10 to 15 days, allowing the female time to rest and for new eggs to develop. After a nesting season, female sea turtles do not nest in consecutive years, returning every two to four years. Olive Ridley and Kemp’s Ridley turtles participate in “arribadas,” synchronized mass nesting events where thousands of females come ashore simultaneously to lay eggs.
Why Egg Numbers Vary and Survival Challenges
The number of eggs a sea turtle lays can be influenced by several factors, including the female’s age, overall health, and the availability of food resources. Larger females, for instance, tend to lay larger clutches of eggs. Environmental conditions can also play a role, with variations observed in clutch size across different populations and years.
Despite the large number of eggs laid, the survival rate from egg to adulthood is low, with only about one in 1,000 hatchlings survive. Natural threats include predation from animals like raccoons, ghost crabs, and birds, which can dig up nests and consume eggs or hatchlings. Environmental factors such as extreme temperatures, coastal flooding from storms, and beach erosion can also destroy nests.
Human impacts contribute to these challenges. Coastal development reduces suitable nesting habitats, and artificial lighting from nearby structures can disorient hatchlings, causing them to crawl away from the ocean and increasing their vulnerability to predators. Poaching and habitat degradation further compound difficulties, highlighting the many obstacles sea turtle eggs and hatchlings face in reaching maturity.