Never as common as the plains bison, the wood bison population was estimated at 168,000 animals in 1800. Wood bison were hunted almost to extinction during the 19th century. By 1893, the population had declined to an estimated low of 250 animals. Numbers slowly increased and had reached 1,500 to 2,000 by 1922. At that time, Wood Buffalo National Park (WBNP) was established in an attempt to save the wood bison from extinction and to protect its habitat.
From 1925 to 1928, 6,673 plains bison were transferred from Buffalo National Park in central Alberta to WBNP. Unfortunately the introduced bison were infected with bovine brucellosis and tuberculosis.
By 1940, it was feared that wood bison had disappeared as a subspecies as a result of interbreeding with plains bison. However, in 1957 federal wildlife officials discovered a herd of pure wood bison in the Nyarling River area of the park. In 1963, 18 bison from that herd that had been tested and found to be disease-free were released in the Mackenzie Bison Sanctuary; 16 of them survived. These 16 animals founded the Mackenzie population.
Following this reintroduction, the Mackenzie population flourished and increased its number and range. Recolonization was characterized by pulses of dispersal and range expansion. The Mackenzie population peaked at about 2,400 animals in 1989. Following peak density, the population declined and appeared to be stabilizing at about 1,500 animals by early 2012.
However, in the summer of 2012, the Mackenzie wood bison population experienced the worst anthrax outbreak known in northern Canada when at least 450 bison died over an 8 week period. In 2013 the Mackenzie population was about 700 animals. Steps have been taken to minimize additional losses from this population. Wood bison harvesting in the Mackenzie Wood Bison Range has been closed for all harvesters as of November 1, 2012. No wood bison can be harvested in the Mackenzie Wood Bison Range.
The Nahanni wood bison population was established when 28 animals from Elk Island National Park were released into the Nahanni Butte area in 1980. These animals dispersed widely, some into northeastern British Columbia. Additional releases were made in 1989 near Nahanni Butte (12 animals) and 1998 near Fort Liard (59 animals). In 2011 the Nahanni population was estimated at 431 animals, similar to the estimate of 403 animals in 2004.
The greater Wood Buffalo National Park population is a large group of wood bison made up of multiple subpopulations found in and around Wood Buffalo National Park. The Hook Lake and Grand Detour subpopulations (together called the Slave River Lowlands) are found outside the park in the NWT. In 2014 there were about 1,100 animals in these subpopulations. Other subpopulations are found mostly within the park, shared by Northwest Territories and Alberta. In 2014 there were about 3,400 wood bison in these subpopulations. Wood bison numbers in the greater Wood Buffalo National Park population declined about 25% between 2009 and 2014.