Great bustard Otis tarda habitat selection in relation to agricultural use in southern Portugal

We investigated habitat selection patterns of the great bustard Otis tarda in a dynamic agricultural landscape in southern Portugal. Combining data from 26 bustard counts with habitat mapping, we used resource selection functions to characterise habitat selection in two areas with different agricultural uses. Selection patterns were compared among areas, seasons (breeding, post-breeding and winter), and flock types (male, female and mixed) during the breeding season. Seasonal differences in selection patterns generally parallelled changes in estimated food availability. Stubbles (i.e. recently harvested fields) and stream margins were preferentially selected by all bustards during the post-breeding period, whereas cereal and fallow fields were selected during winter. During the breeding season, males selected fallow fields more than other habitat types, whereas females selected cereal fields. Habitat selection seemed to be influenced by habitat availability, with birds showing stronger selection for preferred habitats in the areas where they were less available. Great bustards used different habitat types throughout the agricultural year, and we recommend that habitat management promotes a rotational crop system that includes cereal and fallow fields.