BOZEMAN, Mont. (AP) — Hunters and bison managers are seeing a slow season as the Yellowstone National Park herds are largely not leaving the park.

Hunters have killed less than 200 bison as of Friday, and none of the animals have been shipped to slaughter.

Managers last year set a goal of removing between 600 and 900 bison from the herd populations through hunting and slaughter. They planned for at least 372 bison to be removed by the end of January.

A set number of bison that leave the park each year can be killed under the management plan. The plan calls for a bison population of about 3,000. The population was estimated to be about 4,800.

Officials have attributed the slow hunting season to the mild winter.