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Institut de recherche pour la conservation des zones humides méditerranéennes

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Titre :	Habitat of the ortolan bunting Emberiza hortulana on a Causse in southern France (2005)
Auteurs :	J. Fonderflick, Auteur ; M. Thevenot, Auteur ; C. P. Guillaume, Auteur
Type de document :	Article
Dans :	Vie et Milieu - Life and Environment (55(2) juin 2005)
Article en page(s) :	109-120
Langues:	Anglais
Résumé :	We studied the habitat requirement of the ortolan bunting Emberiza hortulana on the Causse Mejean (Lozere, France) during the breeding season by point counts, using a paired-point design (i.e., points with vs. without ortolan), and describing the habitat within a 100 m radius. We compared variable by variable, by mean of Chi(2) tests, the point counts where the ortolan bunting was present (N = 98) with the points where it was absent (N = 94). Most of the ortolan buntings breed in steppe-like grasslands with scattered bushes, and in open shrublands where the mean height of the shrub layer is between 0.5 and 1.75 m. This bird is particularly frequent in Buxus sempervirens shrublands (cover ranging between 10 to 40%). In such open and low habitats, song posts are needed. They mainly consist in scattered trees or tall shrubs higher than 1.8 m, but wires and rocks are also used. On the Causse Mejean, the ortolan bunting clearly prefers slopes to flat areas. Certain environmental variables regarded as important elsewhere in Europe (such as orientation, cover of bare soil, or proximity of farmland) are not relevant on the Causse. Using a vegetation map drawn for the purpose of this study, we estimated at 15 222 ha the area of suitable habitat available to the species, of a total area of 21 314 ha for the bare part of the Causse Mejean. A discriminant analysis performed on the two sets of census points (i.e., with and without ortolan bunting) reveal a good, although incomplete, discrimination, and led us to assume that the present ortolan bunting population on the Causse Mejean does not occupy the entire area of favourable habitat. As a result, possible variations of habitat availability cannot explain alone the present decline of this population.
En ligne :	https://wwwphp.obs-banyuls.fr/Viemilieu/index.php/volume-55-2005/55-issue-2.html

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