Observations were made of the behaviour of a home-range group of Scottish Blackface ewes. The group, including replacement ewe lambs, remained on the hill throughout winter and was offered supplemental feedblocks from December to April. Sheep were individually identified and data collected on ranging behaviour between 06.00 and 18.00 h GMT in autumn and winter. Additionally in winter, records were made of time spent eating from the feedblock or standing within 3 m of it. Age was found to have a strong effect on time spent eating from the feedblock, with older ewes (4 years and over) eating more than younger animals. This was partly attributable to the ewe lambs forming peer groups in winter that were uninfluenced by the movements of mature ewes to the feedblock. Consequently, the majority (0·82) of ewe lambs did not eat feedblock in their first winter. Two- and 3-year-old ewes, although not eating significantly more often from the feedblock than ewe lambs, spent significantly more time standing within 3 m of it and were prevented from eating from it by the competitive behaviour of older ewes. The increased gregariousness of hill sheep in winter appears to be an important factor in preventing the younger ewes taking advantage of the continuous availability of feedblocks. The feedblocks were also found to reduce significantly the size of ewes' home ranges. The results indicate that the social behaviour of hill sheep limits the use of feedblocks to the older and stronger animals in the group. In addition, feedblocks may reduce the utilization by sheep of available winter forage. Alternative strategies for more effective deployment of feedblocks are discussed.