Existing subsistence-settlement patterns proposed for the late Precontact inhabitants of Western Canada assume the parkland was the focus of bison and hunter-gatherer winter activity. This is not supported by information in historic accounts and the archaeological record. Instead, it is proposed that lains-adapted groups regularly remained far out in the grasslands where the concentration of wintering bison was highest. By switching from fat-depleted adults to foetal and newborn bison in late winter/early spring, plains-adapted peoples did not need to use fish and avoided possible deleterious physical effects associated with this change in diet. Parkland- and forest-adapted peoples moved to the northern edge of the grasslands to exploit transient herds on the margins of the wintering range. The diet of parkland- and forest-adapted peoples was more diverse and included the use of spawning fish in spring. These hypotheses are tested using materials from eighteen grassland, transition zone, parkland and forest sites. Gas chromatographic analysis of over 200 residues extracted from cooking pots recovered from these sites is consistent with the faunal and tool recoveries. Wintering sites in the grassland contain mainly cooking pot residues identified as from large herbivores alone or in combination with plants, foetal bison bone and tools associated with a hunting economy. The former inhabitants of transition zone sites also followed a hunting economy in the winter and early spring, but traces of fish use are evident in the tool kits, faunal assemblages and vessel residues. Evidence of the use of fish, in the form of harpoons, fish remains and vessel residues, increases in parkland sites, but is highest in forest sites where it is a major source of food.