During spring and early summer, sexually mature turtles in the wild will seek mates. Pet turtles, those in outdoor ponds or indoor habitats, feel the same urges. If you have mature specimens of both sexes, expect them to respond to those urges -- but be aware that living in a controlled environment may affect the timing of mating behavior. Turtles have courtship rituals, and the female will want to dig a nest to lay eggs.
Every turtle has a body cavity called a cloaca located near the base of the tail, on the underside. It contains the urinary and anal openings. In a male, the cloaca contains the penis, which can extend from the body. In a female, it contains a tract that leads to the ovaries and an area where sperm can be stored.
Male turtles normally reach sexually maturity before females. Red-eared slider females are sexually mature at 3 to 5 years of age, when they are about 5 inches long. Red-ear slider males reach sexual maturity between age 2 and age 4 years, at about 4 inches long. Box turtles are at least 5 years old before they breed. Males' bottom shells have concave undersides to assist breeding activity; the underside of the female is flat or convex to provide more room for her eggs.
Courtship and Mating
Males will often follow a female around and sniff near the cloacal opening before starting the courtship ritual. Water turtles will come face to face with their prospective mates; the male will flutter his clawed front legs around the face of the female and stroke the sides of her head. In some species, the female responds to indicate she is ready to mate. The male then mounts the female from behind and they twist their tails together as he passes semen from his penis into her cloaca. Box turtles perform a similar ritual on land.
Optimal Breeding Conditions
In the wild, the increases in temperature and day length during the spring trigger turtles to mate. Pet turtles in a climate-controlled environment do not receive the strong natural trigger; they could try to breed at any time of year. The female can store viable sperm for several years before laying eggs. Water turtles and terrestrial ones dig nests on land to deposit eggs. Temperature affects the sex of hatchlings -- high incubation temperatures produce females.