Sea turtle nesting and hatching varies by species. The incubation time of eggs also varies by species, clutch size, and temperature. Scientists have observed baby sea turtles hatching throughout the year, but the mostly during the summer and almost always at night.
Turtle Nesting Habits
When do sea turtles lay eggs? That depends on the species again, but nesting is typically in warmer months.
All female marine turtles nest on beaches - typically in tropical, subtropical, and temperate regions. Specific species also tend to nest in the same areas, migrating hundreds of miles from their feeding area to their preferred beaches during nesting season.
Green sea turtles mate every two to four years and lay eggs on the same beach used by their mothers. A typical clutch has 100 to 200 eggs, and a female can lay several clutches before returning to sea. Nesting beaches are usually in Florida, Puerto Rico, the Virgin Islands, and Hawaii.
Loggerheads mate every two to three years and also nest on their "natal" beach. Nesting occurs between April and September, and females lay about 100-120 eggs in about four clutches. Loggerhead turtles primarily nest in two locations - Oman and Florida.
Leatherbacks also mate every two to three years and may lay as many as nine clutches with an average of 80-100 eggs each. Unlike other species, female leatherbacks may change nesting beaches.
Hawksbill turtles have a similar nesting behavior. They mate every two to three years, nest between April and November, and lay about 3 to 6 clutches of 140 eggs each. They also nest in Florida and the Gulf of Mexico, typically at night. However, unlike other species, they nest in low densities instead of large groups.
Kemp's ridley and olive ridley turtles both nest in massive aggregations called arribadas. Thousands of females arrive in waves to lay eggs. 95% of the Kemp’s ridley population nests in Tamaulipas, Mexico. Their nesting season is between May and July when they lay 2 to 3 clutches in daylight hours of about 100 eggs each. Olive ridleys also lay about 100 eggs per clutch, but the timing of their arribadas is unpredictable.
Flatbacks are only found nesting in Australia, with the largest site located on Crab Island in Queensland. Unlike other species, flatback turtle females only lay about 50 eggs per nest.
How Long Does It Take For Sea Turtles To Hatch?
When hatchlings emerge depends on the temperature and humidity of the nest. Hatchlings use a temporary tooth called a carbuncle to break open the shell. They typically emerge at night which reduces their exposure to predators. They leave the nest and crawl toward the water in groups.
Most species hatch after about two months of incubation. At this point, they are incredibly vulnerable to predators like birds, crabs, and some mammals who love to feast on hatchlings. They are also sometimes confused by the light coming from buildings and homes near the beach and crawl toward these places instead of the ocean.
Once they reach the water, a "swim frenzy" begins. Hatchlings drive into waves and ride the undertow out to sea and continue swimming for 24 to 48 hours. This behavior allows the young turtle to reach deeper water where it is less vulnerable to predators.