What kind of beaver is the most dangerous

Invasive species: South American beaver rat will continue to spread

Traders once brought the beaver rat or nutria to Europe from South America to breed in fur farms, but now many of the beaver-like animals live as an invasive species on European rivers and waters. As researchers led by Anna Schertler from the University of Vienna now report in the journal »NeoBiota«, areas in Germany, the Netherlands, Belgium and Luxembourg offer particularly favorable conditions for the beaver-like rodents. The researchers cannot precisely map whether climate change will influence the spread, but they assume that the animals will move to more northerly habitats and that southern Europe in particular will become less livable for them.

Nutrias (Myocastor coypus) look similar to beavers, but with an average body length of half a meter, they are somewhat smaller than those. The herbivores can also be recognized by their round, scaly-covered tail and their dirty yellow front teeth. Since 2015, the rodents have been listed as an invasive species according to the EU regulation. This means that the EU member states are obliged to curb the spread of the animals - for various reasons, as Anna Schertler explains according to a press release from the University of Vienna: “With high population densities, considerable damage is caused to bank reinforcements and in agriculture, for example on corn fields. Natural habitats and rare plant species can also be damaged. «In ten EU countries, including Germany, France, the Netherlands, Austria and Italy, the beaver rat is already an established, invasive species.

Room for improvement for the Nutrias

To find out where the rodents could continue to spread and lodge, Schertler and her colleagues collected more than 24,200 records of nutrias in Europe from 28 countries between 1980 and 2018. With the current climatic conditions, almost 43 percent of the EU (excluding Cyprus) would prove to be a favorable habitat, and nutrias already live in a third of these areas. But so far there have been none of these rodents on almost 73 percent of these inexpensive areas. They could therefore still settle in the regions that suit them. Areas in Germany, Belgium, Luxembourg, the Netherlands and Hungary are particularly suitable for this.

"It turned out that the currently known occurrences do not even cover half of the potentially suitable area in Europe and that a further significant expansion can therefore be expected in the next few years," predicts co-author Franz Essl.

The researchers also examined how climate change could affect the spread. They suspect that especially the regions in southern Europe and partly in central Europe could become inhospitable for the rodents and the animals could move to more northerly regions. The biologists also emphasize, however, that such scenarios are fraught with many uncertainties and must be researched in more detail.

Carrier of toxoplasmosis

As the Viennese researchers also report, nutrias caused considerable damage in the past. In Italian agriculture, for example, damage totaling one million euros was incurred over a period of six years. Experts even estimate the cost of re-paving the bank areas that have been ransacked by beaver rats at ten million euros. The animals also affect the diversity of vegetation in wetlands and destroy the nests of marsh birds. When regions become too dry, the nutrias migrate - the animals can cover distances of up to 120 kilometers in two years, as Schertler and her colleagues write. In addition, the rodents can produce offspring two to three times a year, which contributes to the wide spread of the animals. They are also carriers of diseases such as toxoplasmosis.