In the 18th century, whole truckloads full of living pond turtles were brought from Brandenburg to Silesia as a popular fasting dish. “In the Uckermark in northeastern Brandenburg, pond turtles were offered in restaurants even before the Second World War,” explains Norbert Schneeweiß from the nature conservation association NABU in Brandenburg.
“Today, however, these are only anecdotes from the past. In the meantime, the European pond turtle is considered to be threatened with extinction in Germany, Austria and Switzerland,” continues the biologist. Norbert Schneeweiß had the last natural population in the Uckermark in the 1990s found in Germany. “All of these animals were very old,” the biologist recalls. Apparently, the population had not increased for a long time, the turtles were on the verge of extinction in Germany.
Individual terrapins had also been found in other regions of the country. “But according to our genetic analysis, not a single one of these animals belongs to the German population,” he explains
Head of the Museum for Animal Science of the Senckenberg Natural History Collections Dresden Uwe Fritz. “These specimens came from the Spanish population, for example, and were probably released here,” he concludes.
So the only hope of saving the native pond turtles rested on the ancient shells of the last survivors in the Uckermark. Fortunately, even such very old animals can often still reproduce. And indeed, Norbert Schneeweiß and his student team discovered small caves that a turtle had dug 10 to 13 centimeters deep in the ground in order to lay around a dozen eggs there.
“However, we found these clutches in unsuitable places,” remembers Norbert Schneeweiß. So the eggs lay on field edges, which were plowed up with the clutch long before the little turtles could hatch. Or the expectant offspring was crushed under the tires of vehicles on forest paths.
“Normally, the females in north-eastern Germany dig the burrows for their eggs in places where the sun shines all day,” explains Norbert Schneeweiß. Actually, turtles are animals from warmer climes that allow the temperature to choose the sex of their offspring.
If the daily temperatures in the clutch are above 28.5 degrees in the two or three weeks in the middle of the development of the eggs, only females hatch. If the clutch stays cooler, males develop. More than 28.5 degrees in the clutch cavity are only reached this far north with all-day sunshine. If the females can no longer find such places, only males will hatch. Since pond turtles can live up to a hundred years, it can take several decades before the last female dies and the population disappears. In the past, the females often found such places in the hilly landscape of the Uckermark, which dates from the last Ice Age and has many terminal moraines. On the southern side there were several good spots for successful egg development. Between these hills there were many wetlands with bogs and shallow lakes, where abundant snails, crustaceans and larvae of insects developed, which in turn are the food of the terrapins.
At the beginning of June, the females then set out on an often arduous journey: for females, with their armor usually less than twenty centimeters long, often weighing just one kilogram and webbed feet, it is up to six hundred meters as the crow flies in north-eastern Brandenburg up to such a southern slope today, then a quite demanding day or even multi-day hike.
Depending on the weather, the first tiny creatures hatched from the eggs in mid-August, and even the little turtles that were born in mid-September or a few days later had a good chance of surviving the winter in the nesting hole.
“Even if the mini turtles freeze to death there in sub-zero temperatures, they can survive,” explains Norbert Schneeweiß. In any case, this species is tough: a tortoise survived in an alder swamp forest in the water under a layer of ice for several weeks without the vital oxygen. Animals imported from the south are probably not familiar with such survival skills. That is why the survival of the last population in the extreme north-west of the range is so important: presumably only they can carry on the old traditions of the northern pond turtles.
After the Second World War, however, these survival tricks no longer worked. “Back then, the GDR had to provide itself with food, which is why even the southern slopes of the old end moraines, which were previously only used as meadows, were plowed over,” says Norbert Schneeweiß, describing the beginning of the decline of the last native population.
After reunification, Norbert Schneeweiß found the last survivors, who would hardly have pulled themselves together on their own. So the conservationists took some eggs from the clutches and hatched them artificially. The animals from this conservation breeding now provide young turtles that are released to support the aging populations. In some places, the conservationists paid the farmers, who in return converted their fields on the southern slopes back into meadows that are no longer fertilized and are therefore only mowed once or twice a year or used as pasture for cattle. The conservationists soon found young turtles there.
But then there was a serious setback: since the late 1990s, raccoons, which had once escaped from fur farms, have been multiplying explosively. Native to North America, these invaders love to hunt in the shallow waters on spring nights.
If they find a turtle, the raccoons grab into the openings in the shell with their long claws and simply pull out their limbs or head. “We therefore find injuries up to and including bitten off limbs in up to 80 percent of the pond turtles caught today for research and nature conservation purposes,” explains Norbert Schneeweiß. “On the other hand, we never saw such injuries in the animals caught before the year 2000.”
The conservationists around Norbert Schneeweiß are now defending themselves against the raccoons, for example with electric fences around good breeding areas for turtles, which no raccoon has yet conquered. In another area, hunters are decimating the raccoons, significantly improving the chances of the terrapins. In another area, the wolves that returned to Germany on their own take over the job of the hunters: in wolf territories, raccoons hold back and the turtles take advantage of their opportunities. At least if climate change doesn’t thwart them: “In recent years, increasing numbers Dry and drought periods are increasing, which means that East Brandenburg is now missing the average amount of rain for a whole year,” explains Norbert Schneeweiß.
When bodies of water dry up, conservationists try to gain new habitats for the species, for example by rewetting previously drained wetlands. And then there are also projects to resettle the European pond turtle in suitable waters in the Rhine area and other regions in southern Germany, as well as in Switzerland. The species still has a chance in Central Europe.
