Partial migration, and lek and nesting area fidelity in female Great Bustards

We examined the seasonal movements of wing-tagged and radio-marked adult fe male Great Bustards Oris tarda in a population in northwestern Spain. Four different movement patterns were found: females that migrated between breed ing and wintering areas (20%), females that only left their year-round home range area to mate (32%), females that migrated from a wintering-mating ar ea to a nesting-summering area (16%), and females that stayed all year roun d within a relatively small home range area (32%). All females displayed fi delity to their nesting and wintering areas, and most also showed fidelity to their leks. Migration patterns were not affected either in timing or dis tance by breeding success. The maximum distance between natal and dispersal locations during their first year of life was significantly higher in migr atory females than in sedentary ones. These patterns explained the seasonal variations in population numbers observed in the study area. Surveys showe d that the number of females increased from 600-700 breeding birds, with 1, 000-1,100 birds present from October to March.