The role of extensive cereal crops, dry pasture and shrub-steppe in determining skylark Alauda arvensis densities in the Iberian peninsula

Density and habitat selection of skylarks Alauda arvensis L. were studied in 65 localities of central and southern Iberia. Density was analysed in relation to climatic and geographic variables, as well as to habitat type, by means of linear regression models. Habitat selection was assessed by analysing the relationship of the species' presence with vegetation structure using logistic regression. When all localities were considered, density of breeding skylarks was associated to altitude. During winter, skylark range increased and abundance was related to habitat type. Skylark winter density in dry pasture was 10-20 times higher than in any other habitats. Differences between winter and spring density presented a pattern similar to that found in winter and maximum values were reached in dry pasture. Summer and winter skylark presence showed an association to pasture and shrub <40 cm cover. These results demonstrate the importance of Iberian dry pastures as a wintering habitat for a considerable proportion of skylark European populations. The marked reduction of these habitats in Iberia over the last decades, associated to changes in agricultural practices, might contribute to the overall decline of the species. (C) 2002 Elsevier Science B.V. All rights reserved.