The wisent was hunted out of the Bialowieza forest during and after the First World War, and the last wild individual in the Caucasus followed a few years later. Fewer than sixty animals remained in captivity, scattered across European collections.
Breeders founded an international studbook, the first of its kind for any species, and pooled the surviving stock. Only twelve of those animals ultimately left descendants in the modern population, and they fall into two recognised lines: a Lowland line from Bialowieza stock alone, and a Lowland-Caucasian line that includes a single Caucasian bull. Reintroduction to the Bialowieza forest began in 1952.
The population now exceeds several thousand across more than thirty free-ranging herds, and the species was downlisted from Vulnerable to Near Threatened in 2020. The founder bottleneck remains its central problem: genetic diversity is low, inbreeding is measurable, and the long-term consequences for disease resistance and fertility are still being tracked.