Again from Michael Kubisch.
The European bison or wisent, like its North American counterpart, has faced near extinction during its recent history. Both species have been brought back from the brink starting with relatively small populations — in the case of the European bison perhaps with fewer than 50 individuals. The wisent population now numbers somewhere over 3000, but these animals suffer from low genetic diversity and are furthermore separated into a relatively large number of often very small and isolated herds. This is problematic because it is thought that the survival of a species depends on a minimum number of breeding individuals, although there isn’t necessarily much agreement on what that number needs to be.
There is consensus, however, that the fractured nature of the European bison population is unlikely to guarantee its long-term survival. What is needed is a larger breeding population containing perhaps as many as a thousand individuals. Fortunately, it isn’t necessary for these animals to belong to a single contiguous population, as long as smaller populations exist on stretches of connected land that enable them to come into contact with each other. But even that requires suitable land and lots of it — not an easy quest on a crowded continent.
But there is hope. In a recent study described in the journal Conservation Biology, a multinational group of researchers has determined that the Carpathian Mountains could provide a possible habitat for a wisent metapopulation. This area already contains a number of smaller herds, has the type of vegetation wisent seem to like and (in part thanks to a decrease in human population pressures), and consists of relatively large tracts of suitable land. Implementing this idea would obviously require both existing herds to be enlarged and new ones to be established. Whether the means can be found to accomplish this is hard to predict, but there is no doubt that it would constitute a significant step towards preserving one of Europe’s most magnificent herbivores.