Climate and land-use changes as determinants of lesser kestrel Falco naumanni abundance in Mediterranean cereal steppes (Sicily)

Monitoring of lesser kestrels Falco naumanni is necessary to promote conservation of this vulnerable species. To this end, 35 colonies of this species located in the NNW and SE of Sicily were monitored from 2003 to 2009. Counts of the active colonies and resident pairs were modelled by loglinear Poisson regressions to assess population trends over the study period. Afterwards, a GLM with an analysis of covariance design and a backward removal stepwise regression was performed to relate the observed trend to local- or global-scale climatic variation and to local land-use changes. Colony counts provided a better fit to the loglinear models than pair counts. Loglinear models separated the increasing trend of the SE population breeding in buildings and living in a flat semi-arid area from the non-increasing trend of the NNW population, which breeds on cliffs at higher altitudes and lives in a warm temperate area. The effect of the covariate 'population' suggests a considerable role for the geographic range in modelling the abundance of colonies, which appears to also be relevant when it interacts with climatic and land-use changes. Land-use variables have the greatest weight in predicting the abundance of lesser kestrel colonies. The transformation of arable land negatively correlates with the abundance of colonies in both areas, and the intensification of woody crop cultivation (vines, hops and orchards) is likely to be the major cause of the observed population trend in NNW Sicily. Warm, dry climatic conditions in March and April, during the onset of reproduction, negatively affect lesser kestrels and the largescale climate significantly interacts with land uses. Conservation efforts aimed at the management of suitable habitat conditions of the SE population and the recovery of the NNW population must incorporate the effects of global warming in addition to land-use practices to allow for more effective actions to be taken.