The Yellowstone bison population is thought to exist in at least two separate breeding herds that use northern and central areas of Yellowstone National Park.
Recent and dramatic increases in bison using northern areas and decreases in bison using central areas has raised concern that management
removals have had different effects throughout the bison population.
Bison are managed under an Interagency Management Plan that limits population abundance and distribution.
Under this plan, limited numbers of bison are allowed to migrate out of the park during winter with the remainder lethally removed when migrating beyond park boundaries.
Based on counts during 2017, numbers of bison using central areas of the park may no longer be sufficient for long-term genetic conservation.
However, there is some indication that the herd structure has broken down over time and bison now use both northern and central areas of the park.
If this is the case, with bison conforming to a single, intermixing population, then the current bison population is likely sufficiently large for long-term genetic conservation â¿¿ although there are substantially fewer bison observed in central areas of the park.