Wood bison, North America’s largest land mammal, once faced near extinction. This distinct northern subspecies of American bison has navigated a challenging past. Its journey from widespread populations to a few hundred individuals highlights ecological vulnerability and the profound impact of human activities. Despite these historical setbacks, dedicated conservation efforts have brought the wood bison back from the brink, leading to renewed interest in its current status and recovery.
Current Population Status
Wood bison populations have increased due to sustained conservation efforts. Within Canada, the estimated number of mature wild wood bison ranges from approximately 5,136 to 7,172 individuals across nine isolated subpopulations. Many herds are free-ranging and healthy, particularly in British Columbia, Alberta, Yukon, and the Northwest Territories. However, about 60% of the overall population resides in and around Wood Buffalo National Park, where some herds are affected by diseases like bovine brucellosis and tuberculosis.
In Alaska, where wood bison were once extirpated, reintroduction efforts have established a wild herd in the Innoko River area. This herd, initially 130 animals released in 2015, has experienced fluctuations. As of late 2023, the Alaskan wild population was estimated at 72 individuals after a particularly harsh winter; additional yearlings have been introduced to bolster numbers. Despite these challenges, the overall increase in wood bison numbers since their historic low marks a conservation achievement, though they remain a species of conservation concern.
Historical Decline and Recovery Efforts
Historically, wood bison populations, once numbering an estimated 168,000 in Canada during the early 1800s, faced a sharp decline. Overhunting in the 18th and 19th centuries reduced their numbers to a few hundred by the turn of the 20th century. Another threat emerged from the translocation of plains bison into Wood Buffalo National Park (1925-1928), leading to hybridization and the introduction of diseases like bovine tuberculosis and brucellosis. This interbreeding and disease transmission severely impacted the genetic purity and health of remaining wood bison.
Conservation initiatives began in the late 19th and early 20th centuries with the establishment of protected areas like Wood Buffalo National Park (1922) to safeguard remaining wild wood bison. A turning point came in 1965: 23 genetically pure wood bison were relocated from Wood Buffalo National Park to Elk Island National Park, forming a disease-free breeding population. This herd became a source for reintroduction programs across Canada and Alaska, establishing new, healthy, free-ranging populations. These efforts, involving federal and provincial agencies, contributed to the wood bison’s recovery, leading to its reclassification from endangered to threatened status in Canada by 1988.
Where Wood Bison Roam
Wood bison primarily inhabit the boreal forests and aspen parklands across North America. Their current range is concentrated in Canada, including British Columbia, Alberta, Yukon, and the Northwest Territories. Some populations also exist in Manitoba, which lies outside their historical range. These animals often forage in open meadows, particularly during winter, and some herds prefer willow savannas and open forests.
In Alaska, the Innoko River area in the west-central part of the state is home to a reintroduced wild wood bison herd. This marks their return to a portion of their original Alaskan habitat after an absence of over a century. While their current distribution is more restricted than their historical range, which once spanned from central Alaska to northwestern Saskatchewan, efforts continue to expand their presence within suitable habitats. These reintroduction sites typically feature pockets of grassy meadows within boreal forest environments.
What Sets Wood Bison Apart
Wood bison possess distinct physical and behavioral characteristics that differentiate them from their plains bison relatives. They are generally larger and heavier, making them North America’s largest land mammal, with males weighing up to 1,000 kilograms. A notable physical difference is the shape and placement of their shoulder hump; the wood bison’s hump is taller, more pronounced, and its highest point is located forward of the front legs. In contrast, the plains bison’s hump sits directly above the front legs.
Wood bison also tend to have darker and woollier coats, larger horn cores, and less developed hair on their forelegs and beards compared to plains bison. Behaviorally, wood bison are adapted to forested habitats, often living in smaller groups than plains bison. Their vocalizations during the rut differ, with wood bison having less violent social interactions compared to the plains bison’s roaring. These adaptations reflect their historical preference for boreal forest environments, where their size and physical traits aid in navigating dense vegetation and enduring cold, snowy conditions.