La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Wintering populations of crow species in Mecklenburg-Western Pomerania - results of a night roost survey in winter 2004-05
Auteurs :	Frank Voekler, Auteur
Type de document :	Article
Dans :	Vogelwelt (Die) (128(3) 2007)
Article en page(s) :	131-140
Résumé :	During the 2004-05 winter season, Rooks Corvus frugilegus, Hooded Crows Corvus cornix and Eurasian Jackdaws Coloeus monedula were counted at 52 night roosts in Mecklenburg-Western Pomerania. The wintering population was estimated to consist of 75,000 Rooks, 12,000 Eurasian jackdaws and 7,000 Hooded Crows. Minor roosts of Hooded Crow and of Carrion Crow Corvus corone, belonging to local breeding populations, could have been overlooked. Comparing data from the 1980s with the 2004-05 season, a 50%-reduction of Rooks and an even greater decrease of Eurasian jackdaws was recognised. For the Hooded Crow, no old estimates are available for comparison. The reasons for the lower numbers of Rooks and Eurasian Jackdaws wintering in Mecklenburg-Western Pomerania may be the decrease of local breeding populations, but also reduced breeding populations in eastern Europe and especially a decreasing tendency to migrate in those populations. Due to changes of roost sites within a winter seasons, more synchronised counts are proposed for the future in order to follow the population trends in more detail.

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