European pond turtle

These turtles live in small groups and display pair bonds. There appears to be a hierarchy among the males. Some individuals show territorial behaviors, especially when food resources become scarce. Many behaviors, such as head stretching or biting, help establish the hierarchy between the dominant and subordinate animals. The European pond turtle hibernates in the silt or mud from October to March. Mainly active during the day, it basks in the warmth of the sun and dives into the water at the slightest alarm. This turtle can stay underwater for several hours without breathing. If food resources become scarce or the water source dries up, it can migrate to another body of water several hundred meters away.

The European pond turtle is carnivorous during the first years of its life and becomes omnivorous as it gets older. It eats most small aquatic animals such as insects, larvae, tadpoles, frogs, crustaceans, and even fish. It catches prey with its jaw using a sideways neck movement. Once the prey is captured, it is torn apart using the beak and the claws of the front legs.

During the breeding season, the hierarchy among the males seems to be even more present than during the rest of the year. Breeding occurs mainly from April to May and egg-laying from May to July. During this period, the European pond turtles emit sounds such as whistles or moans.

The female chooses ground that is not susceptible to flooding, digs a hole 12 cm deep using her tail and hind legs, and lays between 8 and 10 white eggs measuring 15 to 25 mm in length, then covers the hole back up. The incubation period is about 100 days. Some hatchlings leave the nest while others do not hatch until the following spring, after overwintering in the egg. European pond turtles can have several clutches per year.

Sex determination is temperature-dependent. This means that the sex of the future individual is determined by the temperature at which the egg is incubated. Changing the temperature causes changes in the hormonal factors that are at the root of gonadal differentiation. A temperature below 25°C leads to the formation of male gonads. On the other hand, a temperature of more than 30°C leads to the formation of female gonads. Growth is determined by ecological factors (such as food availability or habitat quality) and genetic factors.

European pond turtles reach sexual maturity at around 5 or 6 years old and can live for more than 50 years.

The European pond turtle has a special defense technique. Indeed, unlike most turtles, it has a hinged plastron. This unique feature allows it to withdraw into its shell and “close” the openings. In this way, it is protected from predators. However, juveniles and eggs are targeted by herons, bears, foxes, rats, cats…

Numerous threats have impacted and still impact today the populations of the European pond turtle. In addition to pollution, the main threat remains the destruction of wetlands. The drying up of wetland areas for urbanization and agriculture leads to a reduction in vital space and the fragmentation of territory, causing a decline in the numbers of European pond turtles. Fish traps placed in rivers in the 19th century trapped turtles and caused their death by drowning, greatly contributing to the population decline in France, Spain, and Portugal. Furthermore, many takings still occur despite the protection of this species.

The European pond turtle has also suffered from competition with the Florida turtle, introduced by humans into its natural habitat. Indeed, this American turtle, sold in large numbers in pet stores in the 1980s, turned out to be very cumbersome and was released in great numbers into the wild where it acclimated perfectly. However, the European pond turtle and the Florida turtle have the same ecological niche, which means they live in the same environments, have a similar life cycle, and consume the same food resources. However, the Florida turtle, which is larger, heavier, and more aggressive than the European pond turtle, has taken over. Moreover, the Florida turtle lays its eggs in a hole deeper than the European pond turtle, which means it unearths the European pond turtle eggs when it lays its own.

The European pond turtle benefits from a national action plan and is protected in France and in Europe. There are reintroduction programs for the pond turtle.