Farmland habitat selection of wintering lesser kestrels in a Spanish pseudosteppe: implications for conservation strategies

The lesser kestrel Falco naumanni is a globally threatened species, whose b reeding populations seem to have declined due to recent agricultural change s. However, nothing is known about habitat requirements during winter, desp ite the fact that several populations are overwintering in areas affected b y agricultural transformations. We studied population size and habitat sele ction by wintering lesser kestrels in a Spanish pseudosteppe (Los Monegros) , where traditional fallow systems for cereals are rapidly being replaced b y intensive and/or irrigated crops. About 15% of the adult population winte red in the study area, as determined by systematic roadside counts compared with accurate censuses made during the breeding season. Wintering lesser k estrels preferred to forage on field margins and stubble, while avoiding ab andoned fields, ploughs, scrubland, growing cereals and, mainly, the expand ing irrigated crops. This work confirms the need to incorporate the habitat requirements of threatened species over their complete annual cycles; whil e breeding lesser kestrels scarcely use fallow (ploughed at that time), dur ing the winter, fallow (stubble at that time) is their main foraging habita t. Both fallow land and the present agricultural calendar should be maintai ned to assure the conservation of wintering lesser kestrel populations.