On habitat characteristics driving meadow passerine densities in lowland hay-meadow systems in France

For meadow bird conservation in Europe, promoting specific farming models in their remaining strongholds could be a necessary complement to the ongoing agri-environmental policy. This study aims at understanding the main drivers of meadow passerine density in the objective of guiding conservation policies. The data were collected in 56 lowland hay-meadow regions important for grassland bird breeding in France. The objective was to explain, using GLMMs, the variation in meadow passerine density, measured annually in 490 12-ha plots during the period 2006-2010 by the count point method. Explanatory variables enabled us to describe farming management, sward structure and habitat size. Passerine density (all species except the skylark Alauda arvensis) depended on the extent of habitat available and on the percentage of meadow already mown on June 20. More specifically, the skylark was attracted to low, floristically rich and early mown swards, the whinchat Saxicola rubetra and the yellow wagtail Motacilla flava to large areas of favourable habitat, and the corn bunting Emberiza calandra to floristically rich meadows mown later than June 20. Extensive farming models based on late mowing in the largest habitat units should therefore be a target for meadow passerine conservation. The skylark was an exception. Because of its apparent tendency to use early mown grasslands, we recommend to rather invest on alternative habitats for sustaining the demography of this species.