In western North America, tree squirrels such as western gray (Sciurus griseus) and Douglas squirrels (Tamiasciurus douglasii) are potentially important prey for fishers (Pekania pennanti). Masting trees including black oak (Quercus kelloggii) and tanoak (Notholithocarpus densiflorus) produce an important food source for tree squirrels; therefore, forest stands containing these trees may be useful to foraging fishers. Using remote cameras, Andria investigated the effect of mast production capacity on tree squirrel occupancy in forest stands in the northern Sierra Nevada mountains, and how fisher stand use is influenced by the tree squirrel occupancy in a stand. The results of Andria's work indicate that the retention of masting hardwood trees across the landscape may improve foraging habitat for fishers, which will become increasingly important for a species facing the effects of large-scale wildfires, habitat loss, and climate change.