Aardvarks (Orycteropus afer) are keystone African mammals, with multiple species dependent on their burrows as shelter, including from temperature extremes. Thermal refuges may buffer impacts of climate change for these commensal species, yet the aardvark itself may be compromised; a recent summer drought in the Kalahari semi-desert resulted in high aardvark mortality. For two years we studied vegetation productivity, prey availability, diet, body condition, body temperature, and activity patterns of free-living aardvarks in the Kalahari. Termites were the principal prey item, comprising ∼75 % of aardvark diet and providing ∼90 % of dietary energy and water. Termite abundance was linked directly to grass availability, which was dictated by rainfall. Under non-drought conditions, aardvarks met their energetic needs, tightly controlled their 24-h body temperature rhythm (36-37 °C) and were active nocturnally. A drought-induced vegetation decline likely caused local termite population crashes. Concomitantly we recorded a marked deterioration of aardvark body condition and a shift to diurnal activity, including midday foraging and basking. Nutritionally-stressed aardvarks exhibited high 24-h body temperature variability around a mean of ∼35 °C, with 24-h minimum body temperature as low as 26 °C. Drought-induced vegetation decline that reduces termite populations likely will occur more frequently under climate change in Africa, and threaten the survival of aardvarks. We have shown that measurement of body temperature and activity patterns provided direct indicators of physiological well-being of aardvarks and, combined with vegetation indices reflecting resource availability, could predict future aardvark survival.