Local differences in habitat selection by Great Bustards Otis tarda in changing agricultural landscapes: implications for farmland bird conservation

Local changes in land use can influence patterns of habitat selection by farmland birds, thus biasing predictions of population responses to land use changes based on wildlife-habitat or niche modelling. This study, based in arable farmland in south-central Spain, determined whether habitat selection (use of agricultural habitats and the distance to roads, tracks and buildings) by Great Bustards Otis tarda varied between two nearby areas with differing land uses. The western sector has experienced a process of land abandonment and infrastructure development linked to an airport project that started in 1998 and finished in 2009, while the eastern sector maintains extensive dry farmland systems. Great Bustards avoided ploughed fields and selected short- and long-term fallows. Selection of fallows was more intensive in the sector suffering recent land-use changes, where these substrates were more abundant. Great Bustards were distributed further from roads, paths and buildings than would be expected if individual birds selected habitats at random. Avoidance of infrastructure was strongest in the area suffering recent land-use changes. Local patterns of habitat selection seemed to change in relation to agricultural abandonment and infrastructure development. Consequently, conservation measures based on knowledge of broad patterns of habitat use and selection such as agri-environmental schemes may fail to ensure steppe bird conservation locally if such local effects are overlooked. Specifically, schemes should include landscape-scale restrictions on the development and use of infrastructure (roads, tracks and buildings). Analyses of the patterns and causes of local and regional changes in habitat selection are essential to conserve populations of endangered farmland birds.Fabian Casas was supported by a post-doctoral grant from the Junta de Comunidades de Castilla La Mancha (JCCM) while writing this paper. This work is a contribution to the project EASY (Evaluating current European Agri-environment Schemes to quantify and improve nature conservation efforts in agricultural landscapes), financed by the V Framework Program of the EU (www.dow.wau.nl/natcons/NP/ EASY) and to the project AGRIPOPES of the European Science Foundation.Peer Reviewe