SUMMER DISTRIBUTION OF RED-LEGGED PARTRIDGES ALECTORIS-RUFA IN RELATION TO WATER AVAILABILITY ON MEDITERRANEAN FARMLAND

The suggestion that the summer distribution of Red-legged Partridges A lectoris rufa in the Mediterranean region is determined by the availab ility of surface water was examined on the agricultural farm, Alto Ale ntejo, southern Portugal. Partridge coveys were surveyed between 15 Ju ly and 15 August In 1993 and 1994. Using a vector-based Geographic inf ormation System, we assessed, for each covey location and for the loca tions of a double number of random points, the distance to the nearest water point, distance to Geld boundaries,distance to water lines and land use classes, Univariate comparisons were made between the two gro ups of locations, and three multivariate logistic models were fitted t hrough forward stepwise selection to the 1993, 1994 and pooled data se ts to estimate the probability of sighting partridge coveys in the stu dy area. Distance to water was significantly lower for partridge locat ions than for random points in both years and was the only variable se lected for all logistic models, Apart from water availability, Red-leg ged Partridge locations were also affected by land use and distance to field boundaries.