Nesting & Reproduction
Sea turtles usually nest in intervals of two to three years although some nest yearly. Depending on the species, females may nest from one to ten times during a nesting season. Only the females come ashore to the beach to lay their eggs a few weeks after mating.
When the female Leatherback is ready to nest, she will choose a beach without a coral reef, one close to the deep water, such as ’s Beach. Crawling up from the ocean, she will locate a dry area and begin the arduous task of nest excavation. Using her flippers and the rotation of her body, she will dig an egg cavity that is approximately 70 centimeters deep. She will then lay 80 to 100 eggs, a process that can take over two hours. Eggs are often referred to as the size of billiard balls: she lays an average of 80 fertilized eggs and 30 smaller, unfertilized eggs in each nest. After she is finished, she will carefully cover and camouflage the clutch, and may even construct false nests to fool predators. Her role now complete, she will depart to the ocean, leaving her eggs to their fate.
Remarkably, most female turtles share a nesting instinct that drives them to return to the beach of their birth, or natal beach, in order to lay eggs. In fact, her ability to successfully reproduce depends on the ecological health of this original habitat. However, recent satellite tracking data indicates that the Leatherback, unique among turtles in many ways, may return to a range area or region, rather than a natal beach. The Caribbean coastline of Costa Rica is an example of one of the most important Leatherback nesting regions in the world.
When the female turtle comes ashore at night to lay her eggs, she will first dig a body cavity with her front flippers, and then use her back flippers to dig out the nest. Depending upon the species, 80-120 eggs will be deposited in the cavity. Afterwards the female will laboriously cover the nest with sand and often even create another false nest to confuse predators, before she finally crawls back to the sea. Incubation varies with species, clutch size (number of eggs) and temperature, but averages from 45-70 days.