We evaluated hypotheses concerning the distributions of large mammals in a 60 000 km2 study area that encompassed the contact zone between Ontario’s roadless north and the postlogging southern landscape. We estimated occurrence probability in 575 sample units for woodland caribou ( Rangifer tarandus caribou (Gmelin, 1788)), wolverine ( Gulo gulo (L., 1758)), gray wolf ( Canis lupus L., 1758), moose ( Alces alces (L., 1758)), and white-tailed deer ( Odocoileus virginianus (Zimmerman, 1780)). We used ordinations and spatial regressions to assess the contributions of parameters to species occurrence. Roads and cutovers were most abundant in the south, leading to an increased prevalence of deciduous forest. Mature coniferous forest, however, occurred most commonly in the north. Occurrence probabilities for moose and deer were greatest in the south, in close association with deciduous trees. Wolf occurrence was also greatest in the south, positively related to both deciduous forest and road density. Caribou occurrence, however, was positively related to mature coniferous forest and negatively related to both wolf occurrence and roads. Wolverine occurrence was negatively related to deciduous forest. Our surveys demonstrated distinct mammal communities in the northern and southern halves of our study area, a separation that appeared to be mediated by deciduous forest and roads.