By Stacey Venzel
As with most traits among turtles, the amount of time females can hold eggs inside their bodies differs. Turtles are capable of keeping eggs anywhere from weeks to months depending on the species, individual animal and circumstances. As evidenced by false crawls and sperm storage, female turtles are also experts at saving up for later.
On average, the shortest amount of time females hold eggs has been documented at two weeks in loggerhead and green sea turtles, both known for producing more than one clutch of eggs in a nesting season. Biologists Whit Gibbons and Judy Greene relayed a record in which a loggerhead had only eight days between clutches.
Other female turtles wait a little bit longer before depositing eggs. Spanning two weeks to two months, sliders and eastern mud turtles fluctuate in the amount of time they hold eggs inside of them.
Cases of the female chicken turtle keeping fertilized eggs inside her have surprised biologists. In a study reported by Gibbons and Greene, many chicken turtles held the eggs for around four months, but one individual kept them for six months. All of the hatchlings were in good health, demonstrating that long periods of egg holding are not necessarily detrimental to hatchling survival.
Sea turtle nest-laying tracks are easily recognizable on beaches by flipper patterns resembling tire marks that stretch from the ocean to the tide line. Females drag themselves up the sand in search of the perfect nesting location. However, if they are frightened, disoriented, interrupted or find the habitat unsuitable to their nest-building specifications, they will hold any remaining eggs inside, depositing them at a later date.
Female reptiles are known to safeguard sperm for long periods of time with turtle sperm storage documented up to four years. By keeping sperm from a previous mate—sometimes two mates—females do not have to expend energy copulating again before laying subsequent clutches. It is also hypothesized that they can selectively fertilize eggs choosing one father over another.
J C Avise, D E Pearse, “Turtle mating systems: Behavior, storage, and genetic paternity,” Journal of Heredity, 2001, https://jhered.oxfordjournals.org/content/92/2/206.full.
Karen Eckert, David Gulko, Sea Turtles: An Ecological Guide (Honolulu, Mutual Publishing, 2004), 59, 62-63.
Whit Gibbons, Judy Greene, Turtle: The Animal Answer Guide (Baltimore, The John Hopkins University Press, 2009), 59-61.
“Information about sea turtles: Genera behavior.” Sea Turtle Conservancy. http://www.conserveturtles.org/seaturtleinformation.php?page=behavior. author & date not listed