Habitat selection by Little Bustard Tetrax tetrax in a cultivated area of France

The Little Bustard Tetrax tetrax is one of the most endangered species in E urope. The French populations breeding in cultivated areas have suffered a drastic decline during the last 20 years and have disappeared from several locations. In a political context, where management agreements are develope d under EU agri-environment regulations, it has become urgent to identify t he ecological requirements of this species, to predict its response to envi ronmental changes and to suggest management tools, such as promotion of ben eficial farming practices. Despite the fact that many studies have describe d the habitat of the Little Bustard, quantitative data are lacking. We meas ured habitat use in relation to availability in a cultivated plain in weste rn France in 1995. Habitat use by the Little Bustard differed significantly from habitat availability. Some crops, such as oilseed rape and cereals, w ere avoided. Sunflower crops were used by Little Bustard males, but were av oided by females. Females used set-aside to a greater extent than males. Ha bitat diversity was significantly greater around the centre of male activit y than in randomly selected areas. These differences were found for areas w ithin a radius of 100 and 200 m around centres of male activity but not for those with a 300 m radius. Vegetation height was one of the most important variables for calling males, as low vegetation is needed to detect and be detected by conspecifics. The most important variables for females are food resources and, to a lesser extent, predator avoidance. For these reasons, recent changes in land use on arable plains are likely to have different ef fects on males and females. Conservation measures should take into account these differences, the importance of the scale of measurement and should in corporate specific ecological requirements.