European pond turtle

Observing the European pond turtle can be a challenge. Not only because it has become rarer in Portugal – it is an endangered species – but also because it is a shy animal and can spend part of the year in hibernation.

The European pond turtle (Emys orbicularis) owes its Portuguese name (“striped shell turtle”) to the yellow stripes and spots on its shell, head, legs, and tail. A species of diurnal habits, it can hibernate at the coldest time of the year or enter a type of dormancy (known as aestivation) if the area where it lives is dry.

Normally, it remains active from March to September, months in which, with any luck, it is possible to see it near areas of calm or still water, permanent or temporary, such as streams with little current, ponds, marshes, and lagoons surrounded by vegetation. More common in fresh water, it can also live in brackish water areas.

This turtle is classified as an “endangered” species on the mainland, mainly due to the low population density and the fact that its distribution is dispersed across the country, with small and isolated populations. There are several factors that help to explain their decline in the various areas of its distribution, such as pressure from agriculture and urbanisation, the alteration and pollution of aquifers or situations of prolonged drought, which alter their habitats and breeding sites.

The fact that female European pond turtle reach sexual maturity relatively late (between 10 and 12 years old) and fertility rates are low does not help populations to recover from external threats. On the other hand, the species has a high infant mortality rate, and it is estimated that only one in every 100 young turtles reaches adulthood. Still, their average lifespan is long: between four and six decades in the wild.

In addition to these elements, it is also necessary to account for the capture of animals for commercial purposes and the introduction of exotic species, which compete in particular for both space and food. As for its diet, that of the European pond turtle is varied, and is based on small fish, aquatic invertebrates, and also some vegetation.

Did you know that…

• The European pond turtle is in fact a terrapin with certain turtle-like features. There are several distinguishing elements between terrapins and turtles, with the length of their necks and the shapes of their shells being two of the easiest to identify: terrapins have longer necks and a flatter carapace. Food and habitat also differ, as terrapins are mostly carnivores (while turtles eat everything, including vegetables) and live only in freshwater habitats.
• Females are often larger in size and weight than males. The latter are distinguished by the ventral part of their carapace (called a plastron) being more concave. The plastron was, at an early stage of evolution, a predecessor to the carapace.
• These reptiles are derived from terrestrial ancestors and, despite being in the water for long periods and having interdigital membranes that allow them to be able swimmers, they breathe through lungs and they complete their reproductive cycle on land. They mate in the water, but the eggs – between three and 18 per lay – are “hidden” in holes dug by the females.