American Mud and Musk Turtles: Kinosternidae

Although most American mud and musk turtles stay in the water for most of their lives, these turtles are only fair swimmers and move rather slowly. In the rainy season, some turtles may crawl onto land and look for food there, but for the most part, most of the trips to land are for nesting. Some turtles are active only during the day, and some only at night. Others may be up and about at any time of day or night. Those that live in warm, wet climates are active all year. In areas with cold winters and in deserts with long stretches of dry weather, the turtles may be active only a few months a year and spend the rest of the year underground, where they wait for better conditions. This period of inactivity in the winter is called hibernation (high-bur-NAY-shun). A period of inactivity in dry summers is called estivation (es-tuh-VAY-shun). In both cases, the turtle enters a state of deep sleep.

During breeding season, males and females have no real courtship, or mating, rituals. They mate in the water. The females scramble onto land to make their nests. Some dig holes, lay their eggs at the bottom, and then bury them. Others bury themselves first and then dig a deeper hole for their eggs. Still other species skip the hole and simply lay their eggs among leaves on the surface of the ground. Females usually lay three to six eggs in each clutch, or group of eggs, although some clutches have as few as one egg or as many as twelve eggs. The female may lay up to six clutches a year. The oblong eggs range from 0.9 to 1.7 inches (2.3–4.3 centimeters) long and from 0.6 to 1.0 inches (1.5–2.5 centimeters) wide. The eggs hatch seventy-five days to a year after being laid. The nest temperature controls whether the eggs in most species hatch into males or females. Very warm or very cold temperatures produce females, and medium temperatures produce males. In a few species, such as the Mexican giant musk turtle and Pacific Coast giant musk turtle, the nest temperature has no effect on whether the eggs become males or females.