A small group of muskrats arrived in Bohemia in 1905, carried across the Atlantic as curiosities from a hunting trip in North America. Five animals were released into ponds at Prince Colloredo-Mannsfeld’s estate near Dobříš, where they were expected to remain little more than a private collection and perhaps a source of valuable fur. They had other plans. Within years, the animals had moved beyond the estate and into the surrounding waterways, breeding as they went.By 1914, estimates put the muskrat population in Bohemia at around two million. From there, the animals continued their slow spread through rivers, canals and wetlands, reaching neighbouring countries and, through later introductions and escapes, much farther east. More than a century later, the descendants of those early European muskrats are found across a vast stretch of the continent, while countries such as the Netherlands still trap them to protect vulnerable waterways and embankments.
Five muskrats released in Bohemia began an unexpected European spread
This is generally traced to 1905, when Prince Colloredo-Mannsfeld returned to Bohemia after a hunting trip in North America, commonly described as having taken place in Alaska.According to the UNL Digital Commons (University of Nebraska), among the animals brought back were five muskrats: two males and three females. They were released into ponds at his estate near Dobříš, roughly 40 kilometres south-west of Prague.The intention appears to have been practical rather than scientific. Muskrat fur had commercial value, and keeping the animals on the estate offered the possibility of developing a small source of income. For a while, the newcomers were reportedly treated much like captive animals, receiving food such as grain and carrots.Muskrats are well suited to moving through connected waterways. Once animals began leaving the estate, streams and rivers provided a ready-made route into unfamiliar territory. Young muskrats also disperse from established populations, meaning the species did not need people to carry every new group farther afield.Within less than a decade, the situation looked very different. By 1914, estimates placed the muskrat population in Bohemia at around two million animals. The species had moved far beyond the ponds where those original five had been released.
How the muskrat gradually expanded from Bohemia to Japan
Historical records from Europe allowed naturalists and later ecologists to follow the changing boundary of the muskrat’s range. During the early decades, the advancing population front was estimated at roughly 10 kilometres a year, although movement was not uniform. Rivers and other waterways could provide much easier routes than areas without suitable habitat. At that pace, the animal was hardly racing across the continent. It was spreading in increments, generation after generation.Bohemia was followed by neighbouring parts of Central Europe. Muskrats reached Germany, Austria and Switzerland, while separate introductions and escapes helped establish populations elsewhere, including France and Belgium.The species was also deliberately moved for fur production. During the 1920s, muskrats were introduced into Finland, while much larger programmes followed in the Soviet Union from 1928 onwards. Animals were released in different regions, helping the species leap far beyond the original European population and eventually establish itself across parts of Siberia and Central Asia.From there came further expansion into China and Mongolia, with naturalised populations eventually reaching Japan as well.
Rivers and canals helped the muskrat spread one waterway at a time
Muskrats do not need to travel great distances in a single burst to colonise new territory. The animals spend much of their lives around water and are capable swimmers. They excavate burrows into banks and build nests or lodges among vegetation. When populations become established, younger animals can disperse into neighbouring stretches of suitable habitat.That makes a river system rather different from a simple map of open land. A population established beside one stream can gradually occupy another stretch of water, then another. Given enough time, connected rivers, canals and wetlands can turn what looks like a local introduction into a much wider expansion.The muskrat’s European advance therefore became useful to scientists studying biological invasions. Because its spread occurred over decades and was recorded in different countries, it offered an unusually detailed example of how a non-native mammal can establish itself, expand and reach a new geographical limit.
Why European countries keep trapping muskrats
The problem with muskrats in Europe has little to do with their appearance. Their burrowing habits can cause serious trouble where waterways have been engineered by people. A natural riverbank can tolerate a certain amount of excavation. A flood embankment, canal bank or railway embankment has a different purpose.Muskrats excavate entrances below the waterline and can create networks of tunnels inside earthen banks. Repeated burrowing may weaken those structures, particularly where large numbers of animals are present.That turned the species into more than a nuisance for landowners. In countries that depend heavily on engineered water defences, controlling muskrat populations became part of maintaining infrastructure. Much of the country relies on dikes, embankments and other barriers to manage water, so animals capable of burrowing into those structures are treated as a practical threat. Muskrat trapping became a permanent operation, with professional trappers working throughout the year and removing large numbers of animals.The objective is not simply to reduce the population in one field or canal. Dutch authorities have pursued the much harder task of keeping the species from spreading further into the country.Belgium, France and Germany have also maintained control programmes. According to the National Parks & Wildlife Service, in 2017, the European Union formally placed the muskrat on its list of invasive alien species of Union concern. The designation brings restrictions intended to prevent the animal from being kept, transported, traded or deliberately released.
How Britain managed to eradicate muskrats by 1939
There is one particularly unusual chapter in the European story. Muskrats reached Britain through the fur trade rather than from the original Dobříš population. Escapes from fur farms during the late 1920s allowed them to establish themselves, particularly around waterways in the Severn region.According to the study published in Biological Journal of the Linnean Society, titled, ‘The eradication of muskrats and coypus from Britain Get access Arrow’, reveals that Britain responded with a large-scale eradication programme. The campaign lasted years and required sustained trapping rather than a single intervention. By 1939, the established British muskrat population had been eliminated. Once an invasive mammal becomes widespread across interconnected habitats, removing every remaining animal becomes vastly more difficult than preventing the initial establishment.Britain’s experience showed that eradication could work under the right circumstances, particularly when the population was still geographically limited and resources could be concentrated on the affected area.
