La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Home ranges of Kittiwakes Rissa tridactyla and Guillemots Uria aalge during chick rearing at Helgoland
Auteurs :	Volker Dierschke, Auteur ; Stefan Garthe, Auteur ; Nele Markones, Auteur
Type de document :	Article
Dans :	Vogelwelt (Die) (125(1) 2004)
Article en page(s) :	11-19
Résumé :	Owing to the long distances to the nearest seabird colonies in Britain and Norway, the home ranges of seabirds breeding on Helgoland (southeastern North Sea) can be investigated by transect counts at sea. According to ship-based counts from the years 1990-2003, most Kittiwakes are found in a radius of 35 km during the chick rearing period. As a result of an aerial survey on 7 June 2003, the majority of Kittiwakes was distributed in less than 10 km distance from Helgoland. Most Guillemots were seen within 15-20 km (ship) and 5 km (aircraft), respectively. In general, the results of both counting platforms are quite similar. However, ship-based counts accumulated over many years show all important foraging areas for both species, whereas aerial surveys only present a snapshot and therefore can not identify all foraging areas used during the whole chick rearing period. In contrast to ship-based counts. aerial snapshots allow to detect distribution patterns and their temporal and spatial dynamic.

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