ure is directly controlled by its environment. The eggs are laid in July or August, it takes them about ten to eleven weeks to hatch. Eggs are soft and leathery and are generally about 1.25 inches long. An average clutch of eggs is about ten. However, the number is in direct proportion to the size of the female. A large female may lay up to as many as twenty eggs. The nest is relatively close to the surface, only two to three inches below topsoil. This allows for maximum heating, but also for a layer of insulation against the winter cold. Reproduction is the most important thing in the life most animals, assuring the survival of your own species. Painted turtles, like many reptiles, are creatures with temperature dependent sex determination (TSD) (Bull, 1980). In other words, while in the nest, the ambient temperature determines the sex of the eggs. A large part of this equation is vegetation cover. A heavily covered region will not receive as much solar exposure. Less exposure to the sun equals a cooler nest. Also with the nests close to the surface of the soil, they are more influenced by the weather. Clouds or rain or a sunny day would all have drastic effects on the temperature of the eggs. It is assumed that a female painted turtle can sense the coming weather somewhat (Janzen, 1994). In a recent study it was shown that Painted turtles were a temperature dependent species. "The majority of nests each year (66% overall) produced hatchlings of only one sex. Most unisexual nests in 1989 and 1991 were female oriented.; all unisexual nests in 1990 and 1992 were male oriented" (Janzen, 1994). Also it was determined that warmer temperature, or areas with less vegetation produce primarily female clutches. Whereas places that were cooler or had more vegetation produced primarily male hatchlings. This may be one way nature prevent inbreeding in the species. With such a large percentage of animals in a clutch being the same sex it be...
