European beaver on the River Sihl

Castor fiber

In spring 2005, a beaver family moved into a new, species-appropriate enclosure right by the River Sihl at Wildnispark Zurich. Ten years later, the management decided to stop keeping these nocturnal rodents and to use the vacated enclosure for the otters. In early 2024, beavers returned naturally to Sihlwald and now live in the wild right next to the otter enclosure.

From Zurich Main Station to Sihlwald

200 years ago, the Eurasian beaver disappeared from Switzerland due to intensive hunting. Thanks to successful reintroduction projects between 1956 and 1977, the population of these rodents has once again grown encouragingly. Today, there are just under 5,000 beavers in the country. The beavers living in the canton of Zurich mainly originate from releases at the Wasserschloss in Aargau, the Nussbaumerseen in Thurgau and the Thurspitz in Zurich. Beavers have been native to the River Limmat once again for some time. This population has now slowly spread along the River Sihl from Zurich main station, where the Limmat and Sihl rivers converge. Since early 2024, a pair of beavers has been spotted in Sihlwald – right next to the visitor centre of the Wildnispark Zurich, not far from the otter enclosure.

Way of life

Beavers live in near-natural flowing or still waters and, depending on the food supply, their territory extends from 700 metres to three kilometres along the bank. It digs its burrow into often steep riverbanks, with the entrance hidden and protected beneath the water’s surface. The beaver dams serve as barriers to regulate the water level, ensuring that the entrance to the burrow remains submerged even during dry spells. In this way, the beaver shapes its own habitat.

It remains to be seen how the rodent will cope with the Sihl and its highly fluctuating water levels. One thing is certain: as long as the beaver does not endanger any infrastructure or footpaths and cycle paths, it is free to do as it pleases in the Sihlwald. After all, in the nature discovery park, nature is allowed to develop freely.

Reproduction

Beavers are monogamous, and a beaver family consists of the parent pair and two generations of young. The mating season for beavers takes place between January and April, and after around three and a half months, the female gives birth to one to four young. As soon as a new generation is born, the two-year-old young beavers must leave the family.

Diet

The beaver is a strict vegetarian. Its diet comprises around 300 herbaceous or woody plants. Favourites include meadowsweet, white sweet clover, knotweed, dandelions and stinging nettles. In summer, it feeds on a wide variety of plants; in winter, it mainly eats bark – particularly from willow trees.

Threats

200 years ago, the beaver disappeared from Switzerland due to intensive hunting. Thanks to successful reintroduction projects, the population has recovered. Today, it is no longer considered endangered.

Fun fact

Did you know that the beaver has around 23,000 hairs per square centimetre on its belly – where it is most often wet – but only about half that number on its back? Its coat consists of underfur and guard hairs. When diving, a layer of air forms between the two types of hair. This keeps the beaver’s skin dry at all times. The air also acts as thermal insulation.

Want to know more about beavers?

Find out more in the Zoo Animal Encyclopaedia