AbstractDaily and seasonal patterns of free‐ranging Red squirrels (Sciurus vulgaris) were studied by means of radiotracking. On a seasonal basis, two distinct daily activity rhythms were exhibited. In winter, the squirrels had a short, uninterrupted active phase which is probably an adaptation for conserving energy by minimizing the period of heat loss. In summer, the active phase was more than twice as long as in winter, and was usually broken by a rest period. The activity patterns at the equinoxes were intermediate between summer and winter patterns.In summer, the biphasic pattern of daily activity of individuals gave rise to a trend towards bimodality in the activity pattern of the population as a whole, although the rest periods and second active periods of different squirrels were not synchronized. Onset of daily activity was associated with daybreak, but cessation occurred well before nightfall.Superimposed onto the basic seasonal patterns of activity were the effects of feeding requirements, foraging accounting for a mean of 82% of a month's activity. As well as immediate nutritional requirements, the habit of scatter‐hoarding mast had a marked influence on the duration of foraging, causing a peak in activity in September. Although throughout most of the year the foraging time appeared to influence the duration of activity, active time in late winter appeared to be self‐determining, causing squirrels to lose body‐weight rather than to extend the foraging period. Other factors affecting activity patterns are di