The distribution and number of colonies of rooks Corvus frugilegus L. was studied over a three-year period in a landscape in eastern England dominated by winter cereals. Individual rookeries were generally small and not evenly distributed, with a total of 1561– 1637 nests in a 325 km2 study area over the three years. The distribution of groups of rookeries (main colony with satellites) was associated with the amount of grassland, a colony of 100 nests requiring some 122 ha of grass within 1 km. Feeding habitat and preferences of rooks were studied throughout one year. The most consistently used feeding habitat was grassland and it was strongly preferred, with a peak in June. Winter cereals were used from October to March, but were never preferred, other crops being used seasonally. Flock size peaked in February and was smallest during the breeding season, when the mean distance of feeding flocks from the colony was less than 1 km. Increases in land given over to horses, riding and turf production could benefit rooks in the study area.