Understanding space-use patterns of highly mobile animals, such as woodland caribou (Rangifer tarandus caribou Gmelin), is required for ecosystem conservation. We consider the use of lakes in winter as important habitat for woodland caribou both to reduce predation risk and acquire food. To test scale differences relative to caribou use of ice-covered lakes in winter, we compare the use of ice-covered lakes within a regional study area and within sub-regional landscapes at two spatial levels: (1) seasonal selection of winter ranges and (2) daily locations. We used 100% minimum convex polygons with a 500-m buffer for winter ranges, and 500-m radius buffer around individual radio telemetry locations of 27 caribou from 1995 to 2000 as spatial measures of use of lakes of various dimensions by caribou. In the winter-range analysis, caribou used areas with more lakes in the 5–100-ha size class, including lakes with more perimeter, larger area, and higher fractal dimensions as compared with the relative distribution of available lakes. These patterns were confirmed at the regional level (Manitoba border in the west to the Hudson Bay lowlands to the east) and at the sub-regional level. At the finest level of resolution of daily locations, caribou selected lakes with greater area and perimeter in the west but not in the east. Our findings should be considered when developing local plans for forest management and designing landscapes where the conservation of woodland caribou is a goal.