We analyzed the influence of environmental temperature (open versus shaded habitat) and experimental food availability on surface activity of the degu (Octodon degus), a day-active herbivorous rodent that inhabits central Chile. We manipulated food availability and compared open and shaded study plots to determine the influence of thermal conditions on aboveground activity. Degus displayed a bimodal pattern of daily activity during relatively warmer thermal conditions in the austral autumn, whereas activity was unimodal during colder conditions in winter. However, they had a unimodal activity pattern under warm conditions in the shade when food availability was artificially enhanced in autumn. We observed more animals active in the plots where food was supplemented under all conditions. Our results illustrate spatial and temporal shifts in activity of degus involving a trade-off based on avoidance of exposure to heat and the search for food.