RODENT SEED PREDATION IN CEREAL CROP AREAS OF CENTRAL SPAIN - EFFECTS OF PHYSIOGNOMY, FOOD AVAILABILITY, AND PREDATION RISK

Patterns of rodent seed predation in extensive cereal croplands of central Spain were investigated by measuring rodent predation rates on artificial seed patches, together with seed availability, rodent abundance and habitat physiognomy. Sampling was designed to cope with the spatial and temporal variability of factors potentially affecting rodent activity (natural and man-made habitat features, season and moonlight). Rodent predation was unpredictably distributed in summer. In winter, rodents foraged on average in the patches least used by man; moonlight, however, did alter this pattern, so that rodent predation was closely associated with shrubs in the bright nights nad evenly distributed in the dark ones. I conclude that the need of stable underground refuges and predation risk in the winter period seemed to be the main factors constraining rodent foraging activity in the man-made ecosystem studied.