La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	High local density of a population of the Red-backed Shrike Lanius collurio in the region of the Ammersee
Auteurs :	Ursula Wink, Auteur
Type de document :	Article
Dans :	Ornithologischer Anzeiger (47(1) AUG 2008)
Article en page(s) :	66-76
Résumé :	The lake known as the Ammersee lies to southwest of Munich in Upper Bavaria. Between 2002 and 2007 the territories of breeding pairs of the Red-backed Shrike were studied in two areas to south of the lake, each of 15 km(2). One study area lay on the moraines and the other on the plain. Over the six years on average, 68 territories were found in the two areas combined, with a maximum of 81 territories in 2005 (Table 3). Numbers and density of territories on the hills (average 51 territories/15 km(2)) and in the plain (average only 16 territories/15 km(2)) differed markedly. Correlations were found between population density and habitat structure. The main factor influencing the more than three times higher density on the hills was the plentiful availability of potential nest sites in spiny shrubs such as blackthorn, hawthorn, and dog rose. The prevalence of pastures grazed by cattle was also important for feeding, especially in periods of wet weather. The high density of the population of Lanius collurio on the hills south-west of lake Ammersee is only local. In the bordering regions the scarcity of hedges limits density. A high density population can only survive if the structure of the habitat is maintained.

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