The European red squirrel Sciurus vulgaris inhabits areas which undergo profound seasonal declines in food availability and ambient temperature. We measured the body temperature ( T b ) of free-ranging S. vulgaris over the course of one year to examine its thermoregulatory strategies and found no evidence of heterothermy, with T b never dropping below 36.7 °C. A lower average T b and a reduced active phase are likely to have resulted in some energetic savings, sufficient for survival during the particularly mild winter with unhindered access to food stores. We cannot exclude that a different T b pattern may be seen in energetically more demanding years, but we can confirm that heterothermy is not an obligatory behaviour in this species to counter energetic bottlenecks. Either S. vulgaris is indeed a strict homeotherm, or the need for torpor is flexibly adjusted.