Turtles

Most species of turtles mate in the spring or early summer, when the males actively search for receptive females. Courtship may include interesting behavior, such as that of the male red-eared turtle (Trachemys scripta), which swims backward in front of the female, while stroking her head and neck with his greatly elongated front claws. The males of some tortoises make noises during courtship or mating. Smaller species, such as the Mediterranean tortoise (Testudo), cluck like chickens, whereas the giant Galápagos tortoise (Geochelone) bellows.

All turtles lay eggs, which vary in shape from cylindrical to spherical. Smaller species may lay only two or three eggs in a clutch, while sea turtles may lay three or more clutches of 100-150 eggs in a year. Most turtles dig a nesting cavity with their hind feet, lay their eggs inside, and cover the entrance, leaving the eggs to be incubated by the heat of the sun. Typically, the eggs hatch in 60-90 days.

Most turtles are long-lived. The eastern box turtle (Terrapene carolina) may live 100 years, and giant tortoises have been reported to live for more than 150 years. Studies of the vigor of populations of turtles must take the age structure into account. For example, although populations of giant tortoises on certain Galápagos Islands have numerous large individuals, they may nevertheless be endangered if no young are being produced because of excessive predation by introduced mammals.