La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Influence of slope on the spatial distribution of the Skylark Alauda arvensis.
Auteurs :	Ortwin Elle, Auteur
Type de document :	Article
Dans :	Vogelwelt (Die) (126(3) 2005)
Article en page(s) :	243-251
Résumé :	The slope of a location is an important factor in the habitat selection of the Skylark that modifies the effect of other habitat factors. Over a period of two years the influence of slope was quantitatively analysed on two farmland study plots in southwest Germany. The slope on these plots ranges between 0 degrees and 24 degrees. The quantification of slope was carried out by a Geographic Information System (GIS). The selection of different slope classes by the Skylarks was defined by the location of their territories, which were mapped in the field. The differentiation between 'preferred' and 'avoided' slope classes was based on the quantitative comparison between the relative proportions of these classes in the territories of the Skylarks and the availability of these classes on the total study plot. Overproportionally selected slope classes were regarded as 'preferred'. Accordingly, underproportionally selected classes were regarded as 'avoided'. The Skylarks preferred moderate slope values up to 5 degrees. Areas of 7 degrees to 11 degrees slope were still selected by the Skylarks in appreciable proportions. However, these steeper areas were clearly avoided by them. The upper limit of selected slope on the plots was 15 degrees.

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