Problematic desire for frog legs, “toad caviar” and snake eggs: A study documents how the raccoons imported from North America are threatening amphibians and reptiles in Germany. Even in nature reserves, the sophisticated “gourmets” endanger the survival of endangered species. As a result of the advance of the invasive small predator, this damage is now to be expected, say the researchers.
In their North American homeland, the “cute bandits” have always been part of the environment and other species have been able to adapt to them. But in Europe, the raccoons became a problem after they were released in the 20th century. The adaptable small predators find optimal living conditions, hardly any enemies and “unprepared” prey animals. That is why the raccoon is currently spreading almost uncontrollably – with consequences for humans, animals and ecosystems that cannot yet be assessed.
A team of scientists from various German institutions is researching this threat in the “ZOWIAC” project (Zoonotic and Wildlife Ecological Effects of Invasive Carnivores). They have already documented that the raccoon still has enormous potential to spread in Europe and could spread dangerous pathogens as it advances. Basically, it was already clear that he was targeting many native animal species or plundering their clutches. But there are still unanswered questions about the extent of this ecological threat. In the current investigation, the focus was now specifically on the victims among the amphibians and reptiles.
Invaders looked at the paws
“There has long been a suspicion that raccoons are partly responsible for the decline of numerous native reptile and amphibian species in certain areas,” says project manager Sven Klimpel from the Senckenberg Biodiversity and Climate Research Center Frankfurt. In order to shed more light on the hunting behavior of raccoons, he and his team, in cooperation with local conservationists, have now compiled targeted observation and study data in nature reserves in Hesse as well as in Brandenburg and Saxony-Anhalt. The information is partly based on state-of-the-art investigation procedures, such as those used in forensics, to track down perpetrators.
As the team reports, the results reinforce the impression of the invasive predators as eco-vandals: “Using state-of-the-art genetic analysis methods, we have now been able to clearly demonstrate that grass frogs, common toads and yellow-bellied toads are among the prey of raccoons,” says Klimpel. Observations also indicate that alpine newts, green toads and fire salamanders are on the raccoons’ diet. Apparently some of the small predators have also developed special preferences for endangered amphibians, according to research results. In the case of the common toad, its skin venom also fails to protect against predators. Many victim finds show that the raccoons simply skin them with their skilled paws before eating them.
Possibly critical feeding pressure
“In a nature reserve in East Hesse, over 400 skinned toads were counted in one hour – a really depressing record,” reports Timo Spaniol, area manager from the NABU Main-Kinzig district. Apparently there can be real feeding sprees during the spawning season, in which the…
In the end, predators are only after special delicacies: They then prefer to feast on the spawn that is still in the animals and leave the rest of the victim lying around. The same applies when hunting frogs: the raccoons show a preference for their thighs.
In addition, the researchers were now able to clearly identify the raccoons as a threat to the native snakes. The remains of grass snakes were often found in the stomach contents. The highly endangered Aesculapian snake is apparently also on the menu: using genetic evidence, the team in the Rheingau-Taunuskreis study area was able to identify a specimen eaten while laying eggs as a victim of a raccoon. “Raccoon DNA was detected both on the snake and on the opened eggs,” says Annette Zitzmann from the Arbeitsgemeinschaft Amphibian- und Reptilenschutz in Hessen e. V..
The researchers conclude that the study makes it clear how much damage raccoons can do to native amphibians and reptiles. “We see feeding pressure on protected amphibians and reptiles in certain areas, which is sometimes threatening the existence of these species,” says Norbert Peter from Goethe University. The results show a new challenge in species protection and can now also be incorporated into the discussion about how to deal with the invaders. “Protection mechanisms and protection tools for managing invasive species should not be static, but should be regularly reviewed and adjusted in order to meet the overarching goal of protecting biodiversity,” said the team.