North American bison are primarily grazers and forage primarily in grassland and meadow vegetative communities. They had the widest natural range of any North American herbivore, from the arid grasslands of Chihuahua State in northern Mexico, through the grasslands of the Great Plains of the United States and Canada, to the riparian meadows of interior Alaska. They can persist in arid regions (e.g. Mexico and New Mexico) and in areas experiencing deep snow cover (e.g., Yellowstone National Park). Grasses and sedges form the mainstay of the annual diet in all regions. However, summer and fall diets may be broader, including flowering plants, woody plant leaves, and lichens, in addition to grasses and sedges, depending on local availability. Bison excavate snow at foraging sites by sweeping it away using side to side motions of their muzzle. The plains bison undertook seasonal migrations when they were abundant prior to European settlement of the continent. Bison no longer migrate owing to land use change contributing to range restriction and depopulation. The Wood Bison was not migratory and remains so. Both subspecies exhibit strong seasonal aggregation during the calving through breeding seasons (May through August).

The original North American range for Bison bison extended from northern Mexico to Alaska. Plains Bison (B. b. bison) occurred from Northern Mexico to central Alberta, Canada. Wood Bison (B. b. athabascae) occurred from central Alberta, Canada to Alaska, USA. The species' current range is restricted by land use and wildlife management policies in the southern area and by wildlife and reportable disease management policies in the northern portion of the North American range. Bison functioning as wild currently occupy less than 1.2% of their original range (Sanderson et al. 2008, this report).

A recovery program for wood bison has existed in Canada since the early 1960s where the subspecies was designated as 'Threatened' by the Committee on Endangered Species of Wildlife in Canada (COSEWIC). In May 2004 COSEWIC assessed the status of plains bison and recommended listing them as 'Threatened' in Canada. National Refuges and Parks and State parks play an important role in maintaining conservation herds in Canada and the United States. Wild free-ranging herds are managed by government agencies. The Nature Conservancy manages 13 captive herds and the American Prairie Reserve manages one fenced bison herd primarily for conservation objectives. Restoration of large populations of plains bison are being considered in Alberta, southern Colorado, Arizona and northern Montana. The State of Alaska recently reintroduced wood bison to the wild in the Yukon region. Better coordination among various federal initiatives for plains bison conservation is being accomplished by a designated Department of Interior Bison Working Group commissioned by secretarial order in 2008. A Plains Bison reintroduction is scheduled for Banff National Park in spring 2017.

The Bison Specialist Group (North America) produced a bison conservation assessment and action plan that provides support and guidance for policy development and conservation planning and management for public and private sector projects, including: numeric, geographic and genetic status of North American bison, including public and private herds; a review of legislation and policies of individual range states regarding bison conservation; geographic assessment of priority conservation areas in North America (Gates et al. 2010); enhancing the capacity of members of the Bison Specialist Group and organizations they represent to provide timely, innovative and practical solutions to conservation challenges; guidelines for management in support of species’ conservation and ecological restoration.

There are potential opportunities for ecological restoration of herds managed primarily for conservation on federal, state, provincial lands in some jurisdictions (Sanderson et al. 2008, Freese et al. 2007). Recently the U.S. Department of Interior published a document titled “looking forward” where they enumerated potential restoration sites in the United States (National Park Service 2014a). In addition the U.S. National Park Service has identified bison restoration as a key activity in their plan for the next 100 years. Badlands National Park is undertaking a bison range expansion within the parks boundaries that will permit increasing the population management target from 800 bison to >1,000 bison.

There may also be opportunities for establishing herds on Native-owned lands that are managed for combined conservation and socio-economic purposes. A Buffalo Treaty that calls for bison restoration was recently signed among 15 indigenous tribes/first nations in Montana and Alberta. The American Indian tribes  govern over 84 million acres in the western United States. In Montana the Blackfeet Nation is embarking upon a restoration project for plains bison (titled the Iinnii Initiative) in partnership with Glacier and Waterton National Parks in Montana and Alberta. The Assiniboine and Sioux Tribes of Fort Peck Reservation, Montana, also seek to host an operational quarantine facility that will provide an ongoing source of disease free culled Yellowstone bison for the purposes of conservation and cultural restoration throughout the United States. However, there are significant cultural, social and economic challenges in integrating western science-based approaches conservation to tribal communities.

Bison bison athabascae is listed in CITES Appendix II.