Invasive Species - Oxford frogs in Hessen not an issue
During invasive Bullfrogs causing problems in Baden-Württemberg, there is currently no warning for Hessen. A scientific employee of the Hessian State Office for Nature, Environment and Geology (HLNUG) in Wiesbaden stated that there is no known occurrence of the North American Bullfrog. Approximately 150 kilometers to the south, in the Landkreis Karlsruhe, the Bullfrog has established itself, and there was a first detection in the neighboring Landkreis Rastatt in 2023.
"For Hessen, there is therefore the general risk that animals from private or commercial holding are released or escape," explained the HLNUG expert. "At the same time, the species could spread from BaWu (Baden-Württemberg) towards Hessen, for example along the Rhine." The North American Bullfrog is listed on an EU list of invasive alien species of union-wide significance. EU member states must monitor the spread of the species and take action to control the population if necessary. The Frogs are hunted in Baden-Württemberg using boats and small caliber weapons. Divers also collect tadpoles.
HLNUG asks for help from the population
The HLNUG has set up a portal where citizens can report sightings of invasive species. "In the case of the Bullfrog, which has not yet been found in Hessen but is present in neighboring federal states, there is an additional early warning system," added the expert. "In the best-case scenario, measures can be initiated immediately upon first detections, preventing establishment."
Like most invasive species, the Bullfrog is highly adaptable and has advantages over native species. Natural predators like crocodiles are missing in Germany, and females can lay thousands of eggs. After metamorphosis, Bullfrogs are carnivorous and eat all vertebrates and invertebrates they can catch, such as insects, worms, and snails. Bullfrogs can grow up to 20 centimeters long, making them physically superior to native frogs and able to displace other species.
Amphibians are primarily threatened by the loss of their habitats and breeding waters, as well as the fragmentation of their migration routes through road and settlement construction, emphasized the researcher. "Effects from invasive species or, for example, climate change represent additional threats, but only because of the poor starting situation can they be so significant."
- Despite the Bullfrog's presence in the neighboring District Karlsruhe and Rastatt District in Baden-Württemberg, there has been no confirmed sighting in the Level of Hesse yet.
- The European Union, recognizing the North American Bullfrog as an invasive alien species of union-wide significance, requires member states like Hesse to monitor its spread and take necessary control measures.
- The Upper Rhine serves as a potential route for the Bullfrog to migrate from Baden-Württemberg District towards the District Karlsruhe and potentially into Hesse.
- To aid in the monitoring of invasive species, including the Bullfrog, Wiesbaden's HLNUG has established an online portal for citizens to report sightings and serve as an early warning system.
- The impact of invasive species on the Umwelt (German for environment or ecosystem) is often significant, particularly in cases where native species are already under threat from habitat loss and fragmentation.
