Leatherbacks mate in the waters adjacent to nesting beaches and along migratory corridors. After nesting, female leatherbacks migrate from tropical waters to more temperate latitudes, which support high densities of jellyfish prey in the summer. Female leatherbacks remigrate to their respective nesting sites at 2-3 year intervals. Females nest several times during a nesting season, typically at 8-12 day intervals and lay clutches of approximately 100 eggs. Female leatherbacks usually lay their eggs at night. Nesting turtles may decide not to nest if there are too many lights onshore. Those that come ashore seek nesting sites free of debris (tree limbs). If the turtle does not find a suitable site for her nest, she may return to the ocean without laying. Leatherbacks carve out an egg chamber about 75 centimeters (inches) deep in the sand, where they deposit 65-115 eggs. A leatherback can lay 7 to 11 individual nests per season, laying a new nest every 10 days. Between nesting seasons, females will spend 3-4 years feeding to build up enough energy to nest again. Older females typically lay more nests with more eggs
than turtles that have recently reached maturity. The sex of turtle eggs is determined by the temperature of the nest. During the middle third of incubation (days 20-40) the temperature within the nest determines the ratio of males to females; warmer temperatures mean more females while cooler temperatures yield more males. After an incubation period of 60 days the eggs will begin to hatch. The hatchling turtles must emerge from the nest and make their way to the ocean. Ten percent of hatchlings will be eaten by seabirds, crabs, reptiles and mammals on the beach. Only 25 percent of hatchlings will make it through their first few days in the ocean. Just 6 percent of hatchlings will survive their first year. Unlike other species of sea turtles, leatherback females may change nesting beaches, though they tend to stay in the same region. Population estimate ranges between 34,000 and 36,000 nesting females.