The seaweed-eating sheep of North Ronaldsay, Orkney, were used to examine the distribution of a herbivore in relation to patchily distributed food. Seaweed occurred in discrete patches on the beach and sheep distributed themselves amongst the patches to ked. Sheep selected Rhodymenia palmata in autumn and Rhodymenia palmala and Alara esculenta in spring. There was a statistically significant agreement between the distribution of food and the distribution of sheep between patches. There was a significant correlation between the distribution of the two sexes between patches. The sex ratio in patches differed from the beach as a whole, probably due to social groupings. Social organization will constrain, and may account for, the unexplained variation in the sheep distribution.