Solothurn site deemed suitable for European bison

A four-year trial has found that the landscape around Welschenrohr can support European bison. The Wisent Thal Association reached that conclusion after keeping a herd at Sollmatt, in the Solothurn Jura, and published its final report on Friday, October 23, 2026.

The trial began in September 2022 with five animals. By summer 2026, the herd had grown to 14, with regular births. The association reported that the bison stayed healthy, developed a stable social structure and made use of both woodland and open countryside.

The findings establish that the site offered suitable living conditions for the animals in an enclosure. They also provide experience with monitoring, management, prevention and everyday coexistence with people. Those practical lessons matter in a region where woodland, farmland and public access sit alongside the proposed bison habitat. But the trial’s conditions do not establish whether a large or free-roaming herd could be viable over the long term. The association says that would require experience on a significantly larger scale and in more natural conditions.

The herd grew from five animals to 14 during the trial, with regular births recorded at Sollmatt. The association’s report says the bison remained in good health throughout the four years and formed a stable social structure.

The animals used both wooded areas and open countryside, a pattern that helped the project assess how they behaved across different parts of the site. The trial also gave the association experience in monitoring and managing the animals, as well as preventing problems and handling contact with people.

Those results support the conclusion that the Solothurn Jura location can provide suitable conditions for bison under the enclosure arrangements used. They are not a verdict on a free-roaming herd. The association says a larger-scale and more natural setting would be needed to assess the long-term ecological, economic and social viability of such a herd. For now, the report offers practical evidence from a growing herd at one site, while keeping the question of a wider return open.

The trial recorded both limited tree damage and a marked drop in meadow yields. Researchers involved in the project found no increase in browsing damage to young trees. However, 9% of the trees examined showed signs of bark stripping.

On meadows grazed by the bison, yields fell by around 20%. The report also notes a practical safeguard for nearby farms: simple electric fences effectively protected neighbouring arable land from damage.

These findings show how bison activity can affect different parts of a working landscape. The measured effects varied between forest, grazed meadow and cultivated fields, giving the association concrete experience with prevention and management during the enclosure trial. They also form part of a wider assessment that includes ecological and economic viability. The association’s report cautions that experience from the enclosure cannot settle how those effects would play out for a large-scale or free-roaming herd; it says assessment would need significantly larger and more natural conditions.