CONFLICTS BETWEEN LESSER KESTREL CONSERVATION AND EUROPEAN AGRICULTURAL POLICIES AS IDENTIFIED BY HABITAT USE ANALYSES

European pseudo-steppes have suffered from extensive changes in agricu ltural practices during the past decades with the disappearance of fie ld margins and fallow systems and the increase of biocide treatments. The negative effect on wildlife has led to the adoption by the Europea n Union of policies more compatible with environmental conservation, b ut decisions about optimal land use are difficult to make because of l ack of information. We studied habitat use by the Lesser Kestrel (Falc o naumanni), a globally vulnerable species, in a Spanish pseudo-steppe (Los Monegros) where traditional agro-grazing systems are still being practiced,and we compared the results with those of another Spanish p seudo-steppe where modern and intensive agriculture has been implement ed. We focused on the use by Lesser Kestrels of habitats subject to ch anges provoked by recent agricultural policies. Habitat availability w as determined in a 3-km radius around 11 colonies, where 23 Lesser Kes trels were radio-tracked during the chick-rearing stage. Habitat selec tion was determined through compositional analysis. the rank of select ed habitats was similar for all kestrels,considering both habitats sur veyed and habitats where kestrels bunted. Kestrels selected field marg ins and cereal fields and rejected abandoned crops and scrubland. This selectivity seemed to be due to prey availability. In the intensively cultivated areas the kestrels selected similar habitats but used only small foraging patches and obtained smaller prey than in the traditio nal agro-grazing systems, probably because of the irregular distributi on of prey resources as a result of the intensive biocide treatments. Consequently, in intensively cultivated habitats Lesser Kestrels had l arger home ranges (63.65 km(2)) than in those with traditional systems (12.36 km(2)). These differences are reflected in the productivity an d population trends of both populations. Thus, the best strategy for c onserving the Lesser Kestrel seems to be the maintainance of tradition al cereal cultures with low biocide treatments and numerous field marg ins. Both agricultural intensification and marginal land abandonment ( with subsequent scrubland invasion) have detrimental consequences for this and probably for other pseudo-steppe species. Positive management steps can be encouraged by recent agro-environmental regulations such as the 2078/92 European Union Reglament, which favors the creation of programs in which agricultural practices accord with wildlife conserv ation.