La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	[Population density and population development of Magpie Pica pica and Common Crow Corvus c. corone in Rheinland-Pfalz (Southwest-Germany)]
Auteurs :	Klaus Fischer, Auteur ; Jochen Martens, Auteur
Type de document :	Article
Dans :	Vogelwarte (40(3) November, 2000)
Article en page(s) :	212-223
Langues:	Allemand
Résumé :	Population density of Magpie and Common Crow was investigated in 16 study areas (about 208 km2 in total) in Rheinland-Pfalz (Germany) during winter 1996/97 and breeding season 1997. The winter abundance amounted to 1.4 and 3.2 ind./km2 for Magpie and Common Crow, respectively. Breeding density was 0.7 pairs/km2 for both species. In case of Common Crow, additionally a considerable number of non-breeding birds was found (0.7 ind./km2). The higher abundance of Common Crow in winter compared with the breeding season is probably caused by overwintering birds from populations originating north and east of Rheinland-Pfalz. Comparative studies in various control areas revealed data on population development in both species during the period 1983-1997. Accordingly, the stock of Common Crow was found to have been more or less stable for the past 15 years, whereas Magpie showed a temporary increase in numbers and after that a decline to the same population density as before. The reason for the latter seemed to be variable persecution pressure.

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