La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Habitat utilization by Northern Wheatears (Oenanthe oenanthe) stopping over on an offshore island during migration
Auteurs :	Julia Delingat, Auteur ; Volker Dierschke, Auteur
Type de document :	Article
Dans :	Vogelwarte (40(4) Dezember, 2000)
Article en page(s) :	271-278
Langues:	Allemand
Résumé :	During migratory stopovers on the small offshore island Helgoland (North Sea), Northern Wheatears equally used grassland and beach habitats in spring. An increasing proportion of wheatears present in beach habitats during autumn migration can be attributed to declining food supplies in grassland habitats and abundant food supply in wrack beds on beaches, but habitat quality regarding protection from aerial predators was difficult to figure out. Individually colour-ringed birds revealed different patterns in utilization of the two habitat types. Grassland birds were transient and explorative with most individuals departing on the day of arrival and high mobility on the island. In contrast, higher proportions of beach birds stayed for at least one night and remained close to their place of ringing, often showing territorial behaviour (which was absent in grassland birds). The results underline the role of habitat quality in stopover behaviour, proposing that birds might quickly judge their expected refuelling capabilities in relation to the resulting migration speed (according to the hypothesis of time-minimization in optimal migration).

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