Yellowstone National Park administrators say shipments of wild bison to slaughter are done for the winter after almost 600 animals were removed in an effort to shrink their numbers.

Federal and said Friday that 258 migrating bison were captured and transferred for slaughter. Hunters have killed at least 264, and 60 were placed in an animal contraception experiment.

The removals were part of an ongoing effort to reduce Yellowstone's herds to about 3,000 under an agreement with Montana.

Wildlife advocates contend the capture and slaughter program is unnecessary, citing research that says Yellowstone could support far more bison than the 4,600 counted last summer.

Ranchers outside the park have a low tolerance for the animals because of concerns about bison spreading disease and edging out cattle for grass.