Many of them have come a long way. Immigrants of animals and plants that are spreading more and more in Berlin. Not all newcomers are as harmless as they first appear. By their extreme hunger, they destroy ecosystems. Its toxins can be dangerous to humans.
Berliners became really aware of the migratory animals when the American swamp crawfish was first seen in the meadows and trails of the Tiergarten in 2017. The American crab, as it has since become famous, caused a lot of excitement.
Presumably, the offspring of abandoned animals multiplied unnoticed before hunger or lack of space forced them out of the garden water. Every summer, crab invaders are caught, which are actually native to the southern United States and northern Mexico. Further spread must be prevented and the multiplication process must be slowed down. Because voracious and migratory animals pose a threat to local species and ecosystems.
Pests in Berlin: even giant pigweed is poisonous
According to the Federal Agency for the Protection of Nature, about 900 foreign species have settled and spread permanently in Germany. Also in Berlin, where some foreign species are prevalent, especially from the plant kingdom, which are dangerous to humans.
For example, giant hogweed: its juice contains the poisonous substance furocoumarin, which provokes allergic reactions even in small quantities. Depending on the severity of contact and personal composition, symptoms range from skin redness and itching to swelling, fever, and circulation problems. You should look carefully when walking in the gardens and look for a place to sunbathe.
The tree of paradise, which comes from Asia and is dotted with greenery, is not entirely without. It crowds out other plant species. It also sticks to concrete in every crack and can damage roads and walls. Touching it can cause allergic reactions in people. In contrast, narrow-leaved aquatic weeds are still harmless. The plant, which the owners of aquariums are famous for, spreads rapidly in the subsoil of the lakes, forming semi-underwater forests there.
Egyptian goose displacing native species
The list of invader animals also includes the Egyptian goose, which is already at home in Egypt. Naboo experts doubt: these geese come from breeds in Great Britain and Holland that escaped from captivity or were abandoned. Experts fear that the Egyptian geese could replace the native wild bird species.
The real animal tormentors of the metropolitan area are raccoons and coypus. They don’t dig around in our trash cans or nest on rooftops and make a mess there. Raccoons and Co. also spread diseases that are dangerous to pets (rabbit plague, tuberculosis).
The American raccoon feels truly at home in Berlin. More than 800 families live mainly in the suburbs of Spandau, Reinickendorf, Marzahn, Treptow and Köpenick.
66 species of animals and plants are included in the list drawn up by the European Union Commission, the so-called Union’s List of Invasive Species. Member states must prevent the introduction of this species and stop its unchecked spread once it has arrived. This also applies to Berlin.
“In the case of species that are not yet indigenous here, there is a very good chance that they will be turned away,” says Ingolf Kühn of the Helmholtz Center for Environmental Research (UFZ). “With species that already exist, such as swamp crab or giant hogweed, they can no longer be eradicated. Then it comes to the issue of containing stocks and keeping species away from particularly sensitive areas such as nature reserves.”
Pest control is a task of Sisyphus
In Berlin, the Senate administration tasked a fisherman with emptying traps set at least twice a week during high season and selling the animals to restaurants, among others.
However, the knife and fork can rarely be used against invasive species – and combating them is often a task for Sisyphus. “There is often not enough capacity for that,” says Sebastian Kohlberg, a species protection advisor at Naboo. “Low nature conservation authorities simply lack financial and human resources.”
Kohlberg says that relying relentlessly on expelling invasive species is often ineffective. Focusing all efforts on managing one type of conflict is not a sustainable strategy. It often makes sense to strengthen the health of the ecosystem as a whole.
“Especially with plants, many starters don’t cause any problems, quite the contrary,” says wildlife expert Dirk Elert of Environmental Management. “Our gardens would probably have a much smaller number of species if there were no new plants.” In general, nature is constantly changing – as is the assessment of animal and plant species.
“The tree of paradise, which originated in China, was planted here about 250 years ago and has been cherished and cared for as a beautiful city tree for a long time,” says Eilert. “About 80 years ago, the species was spreading widely because the winters are getting warmer and the young trees, sensitive to frost, are increasingly surviving.” Today, the plant, as described, is both problematic and officially undesirable.
Pests: Once Wanted, Now Unwanted
Several species considered problematic today were deliberately introduced: the raccoon, for example, as a source of fur, and the Asian lady beetle for biological pest control. Today they are a species that can no longer be expelled.
The situation is unlikely to improve with climate change. According to the researcher at UFZ Kühn, the frost-loving species can become less. However, the majority of introduced species come from warmer countries and will benefit from the expected changes.
“Back off the beginnings,” says wildlife expert Ellert. “Once a species has established itself, there is often little chance of getting rid of it.”