Understanding the life cycle of any given animal is important to its well-being as a pet. For turtles, you should know that they are oviparous, or egg-bearing. Gestation is a word that is commonly confused with incubation, which most mammals don't experience. There is a difference between gestation and incubation, and it's important to know the time periods for both.
Gestation and Incubation
It is very important to understand the difference between gestation and incubation, especially if complications arise in either period. Gestation is generally accepted as being the period during which the eggs develop inside the mother animal, before they are laid. Incubation is the period after the eggs are laid, during which they need to be kept warm, or incubated, until they hatch. You should know the difference between the two, especially if you are in contact with a veterinarian during breeding.
Turtles have evolved with certain survival mechanisms, the most obvious of which is the hard shell that encompasses the turtle and protects it in times of danger. A lesser known defense is what is called sperm retention. Once bred, a female turtle can retain the sperm for up to two years without starting to develop eggs, until she finds a safe place during optimal climate conditions. For this reason, it is difficult to assess exact gestation periods, which also differ widely from species to species. What is known, however, is that turtle breeders with happy turtles report that most pet turtle species lay eggs within two weeks of breeding. From this, we can assume that the normal gestation period is between one and two weeks.
If you were impressed by the fact that female turtles can retain sperm until it is safe to begin gestation, then you will be equally surprised to learn that the development of turtle eggs can be slowed or halted due to climate conditions. This is called diapause, which can last from several days to several weeks. If there are no climate conditions to halt incubation, turtle eggs can begin to hatch at about 45 days at the earliest. Other species can take considerably longer to hatch -- even up to a year.
Although few scientists or veterinarians have taken the time to truly study complications that arise during the gestation of turtles, there is one common condition that can befall nearly any egg-laying creature. It is called egg-binding, or dystocia, and it occurs when a mother creature is unduly stressed or subject to malnutrition during or before gestation. When this happens, eggs inside the mother bind together, and the mother cannot lay them. This condition is often fatal for both mother and offspring, but you can help prevent it by providing a calm habitat and calcium-rich foods for your turtles.