Just before the nesting season, male loggerhead sea turtles migrate to mating grounds, which are usually located offshore from nesting beaches. They wait for females to begin courtship and mating. A male will circle a female, then approach her and bite her neck or shoulder. He will then attempt to mount her and, if she accepts him, they will mate. If a female does not accept the male she covers her cloaca and swims to the bottom, but a persistent male may wait until she needs air and make another attempt. Males use the long, curved claws on their forelimbs to hold on because mating may last for hours and other males often ram and bite the mating male, attempting to dislodge him. If a male is dislodged, another may quickly replace him.
During the nesting season a female may lay several clutches, and will re-mate each time. In some cases, she may mate several times between clutches and so a single clutch may have sperm contributed by several males.
Mating System: polygynandrous (promiscuous)
Peak mating season for Caretta caretta occurs in the early summer months. During this time, males remain in the waters offshore of the nesting beach, while females alternate between mating in the water, nesting on land, and feeding in estuaries and reefs. A female will nest every 12 to 17 days, or 2 to 5 times, during the breeding season. For each nest she must drag herself onto land, where she is in much greater danger of predation, and excavate a nest. Into this nest she lays 110 to 130 round eggs. The eggs incubate for 45 to 80 days, depending on temperature. Loggerhead sea turtles reach sexual maturity at carapace lengths longer than 90 cm, which can occur between 10 and 30 years of age.
Breeding interval: Loggerhead sea turtles breed, on average, every 12 to 17 days during the breeding season. Females will not breed again for another 2 to 4, but possibly up to 9 years.
Breeding season: Breeding may occur year-round, but it peaks between May and July.
Range number of offspring: 23 to 198.
Average number of offspring: 110-130.
Range gestation period: 46 to 80 days.
Range age at sexual or reproductive maturity (female): 12 to 35 years.
Range age at sexual or reproductive maturity (male): 12 to 35 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous
Average number of offspring: 115.
Parental energy investment in loggerhead sea turtles is largely pre-ovipositional, there is no parental care of young. Females provide nutrition in the form of yolk which is used by embryos for growth and development; residual yolk can probably support a hatchling for several days or weeks. Females also expend considerable energy when migrating to nesting beaches and in the ovipositional (nesting/ egg laying) process. Male investment is largely during courtship and mating, and in sperm production.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female)
- Spotila, J. 2004. Sea Turtles: A complete guide to their biology, behavior, and conservation. Baltimore, Maryland: The Johns Hopkins University Press and Oakwood Arts.
- Ernst, C., R. Barbour, J. Lovich. 1994. Turtles of the United States and Canada. Washington and London: Smithsonian Institution Press.
- 2006. "MarineBio" (On-line). Carretta caretta, Loggerhead Sea Turtle. Accessed October 07, 2006 at http://marinebio.org/species.asp?id=163.
- 2006. "NOAA Fisheries" (On-line). Loggerhead Turtle (Caretta caretta). Accessed October 07, 2006 at http://www.nmfs.noaa.gov/pr/species/turtles/loggerhead.htm.
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