European bison (wisent) were extinct in the wild by 1927 but have been successfully reintroduced through zoo-based breeding programs, representing one of conservation's greatest welfare success stories.
The European bison recovery demonstrates what coordinated zoo breeding and reintroduction programs can achieve for species welfare at population scale. Captive bison in participating zoos contribute to a carefully managed genetic reservoir that has prevented extinction. Reintroduced populations benefit from growing in size and genetic diversity, improving long-term welfare resilience. Individual welfare in reintroduced herds requires monitoring of social dynamics, access to appropriate forage, and veterinary oversight particularly in the establishment phase. The UK's Wilder Blean project demonstrates how bison reintroduction can simultaneously improve wildlife welfare and restore ecological function.