<p>Wildlife species that share resources may experience niche overlap and competition across spatial, temporal, or dietary dimensions. Mesocarnivores often overlap in habitat and food requirements. Temporal niche partitioning may facilitate co-occurrence, but the environmental and behavioural processes behind this are not well understood. We used five years of remote camera data to investigate temporal niche partitioning among six sympatric mesocarnivores—short-tailed weasel (<i>Mustela erminea</i>), American mink (<i>Neogale vison</i>), American marten (<i>Martes americana</i>), fisher (<i>Pekania pennanti</i>), wolverine (<i>Gulo gulo</i>), and Canada lynx (<i>Lynx canadensis</i>)—in British Columbia, Canada. Our study spanned a period of fluctuating snowshoe hare (<i>Lepus americanus</i>) abundance, coinciding with decreases in lynx and increases in fisher abundances. These shifts allowed us to test whether smaller species altered activity patterns in the presence of larger ones (size-dominance hypothesis) and whether activity varied with prey availability (prey-abundance hypothesis). Supporting the size-dominance hypothesis, marten activity differed in the presence of lynx and fisher, while lynx and wolverine maintained consistent patterns regardless of smaller species. Supporting the prey-abundance hypothesis, the activity patterns of marten and lynx differed during a hare population low. These results suggest that mesocarnivores display plasticity in temporal activity that may reduce interspecific competition and facilitate co-occurrence.</p>