Distribution of the great and the little bustard in the study area that comprises the majority of Europe, North Africa and Southwest Asia according to Hagemeijer & Blair (1997), Eken & Magnin (2000), Alonso et al. (2005) and Palacin & Alonso (2009). Regarding climatic variables, raw temperature and precipitation data were extracted from WorldClim (http://www.worldclim.org/) according to the Climgen Statistical Downscaling for the ‘current’ period 1961-1990 and for the future periods 2050 and 2080, the latter periods according to the emission scenario A1B in three different general circulation models (GCMs): CGCM31, ECHAM5 and HADCM3. We calculated three bioclimatic variables: cumulative annual rainfall, temperature range between July and January, and the mean temperature during the reproductive period for both species, i.e. between April and July. We also obtained the mean slope of the UTM cell (derived from GLOBE et al. 1999) and the percentage of dry crops and pasturelands in each cell (obtained from the USGS Land Cover, http://edc2.usgs.gov/glcc/glcc.php). Additionally, we included the mean value of human population density (obtained from ORNL 2009).