Yellowstone National Park began its bison culling program today, according to a news release.

The park and other partners of the Interagency Bison Management Plan will cull between 600 and 900 of the iconic animals that migrate out of the park's northern boundary to reduce population growth and the potential for a mass migration into Montana.

Federal, state and tribal members of the IBMP will use hunting as the primary method to reduce the population. This winter, more than 300 bison have been killed through treaty and public hunting outside the park.

However, that was not enough to manage the herd. So more animals will be captured at Stephens Creek and transferred to tribal groups for processing and distribution of meat and other parts for food and cultural practices. Tribal hunts are anticipated to continue during the operations at Stephens Creek.

Stephens Creek is a park administrative area -- including corral operations, equipment storage, a nursery and a firing range -- closed to the public throughout the year. The park imposes an additional area closure during the culling for safety.

The park conducted a tour of the Stephens Creek facility for media and stakeholders on Jan. 20 so they could learn about the operations. The park also will offer two opportunities for media and stakeholders who already have registered to view operations between February 15 and March 15.

However, journalist Christopher Ketcham and wildlife advocate Stephany Seay assert that isn't enough. The park granted these two viewing times after they filed a lawsuit in Wyoming U.S. District Court, claiming denial of access violated their free speech rights to observe a federal action on federal land. On Feb. 5, U.S. District Court Judge Scott Skavdahl denied their request for a preliminary injunction to stop the culling unless they could get the access they wanted.

The National Park Service values bison because they are a native wildlife species, and  play an important role in preserving the ecology of the greater Yellowstone area. Migration shapes how they influence the ecosystem. Bison now have access to the entire habitat throughout Yellowstone National Park, according to the news release.

The National Park Service continues to look for alternative ways to manage bison, including work with the State of Montana to replace the current management plan. It also has extended the public comment period to Feb. 29 on an environmental assessment about the use of quarantine to identify brucellosis-free Yellowstone bison for relocation.

In 1995, Montana sued the National Park Service because bison were migrating out of the park onto state lands. A court-mediated settlement was reached in 2000 creating the Interagency Bison Management Plan. The settlement requires Yellowstone National Park to manage for a target population of 3,000 bison. The average population in the past decade is about 4,000.

The IBMP signatories include the National Park Service; the U.S. Forest Service; the Animal and Plant Health Inspection Service; the Montana Department of Livestock; the Montana Department of Fish, Wildlife and Parks; the InterTribal Buffalo Council; the Confederated Salish and Kootenai Tribes; and the Nez Perce Tribe.