În 1905, un prinț boem a eliberat 5 șobolani în iazurile domeniului său. În mai puțin de un deceniu, în Boemia existau în jur de 2 milioane de bizami

A small group of muskrats was brought to Bohemia in 1905, leading to a significant population increase across Europe. Initially intended as curiosities, they escaped and thrived, spreading through waterways. By 1914, their numbers reached around two million, and they expanded into neighboring countries, even reaching Japan. Their presence has prompted ongoing control measures in various European nations to protect water infrastructure. In 2017, the EU classified muskrats as an invasive species, imposing restrictions on their management.