Efficacy of anticoagulant rodenticides applied to Norway rats (Rattus norvegicus) in the sewer system of Berlin, Germany

When second generation anticoagulant rodenticides used to control rats in sewers come in contact with water, the active substances accumulate along the aquatic food chain.Residues of these substances have already been detected in fish and their predators, such as Eurasian otters (Lutra lutra), cormorants (Phalacrocorax carbo), and common merganser (Mergus merganser).Despite their potentially detrimental effects to the wider ecosystem, rodenticides are still used to control urban rats in sewage systems.However, some cities like Zurich (Switzerland) and Erfurt (Germany) are managing urban rats without using rodenticides in the sewers.