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Wide-range dispersal in juvenile Eagle Owls ( Bubo bubo ) across the European Alps calls for transnational conservation programmes

Aebischer, Adrian ; Nyffeler, Peter ; Arlettaz, Raphaël

In: Journal of Ornithology, 2010, vol. 151, no. 1, p. 1-9

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    Titre
    • Wide-range dispersal in juvenile Eagle Owls ( Bubo bubo ) across the European Alps calls for transnational conservation programmes
    Auteur
    • Aebischer, Adrian. Division of Conservation Biology, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012, Bern, Switzerland
    • Nyffeler, Peter. Division of Conservation Biology, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012, Bern, Switzerland
    • Arlettaz, Raphaël. Division of Conservation Biology, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012, Bern, Switzerland
    Type de document
    • Postprint
    Identifiant OAI-PMH
    • oai:doc.rero.ch:314882
    Summary
    Although juvenile dispersal is an important life history component, it remains one of the less understood ecological processes regulating the dynamics of animal populations. Lack of information about patterns of dispersal hampers the estimation of the actual status and demographic trajectory of populations, and can preclude the development of sound conservation strategies. The Eagle Owl Bubo bubo is an endangered bird species in the European Alps. Many breeding sites have been abandoned in the twentieth century, although some recovery has been reported lately. Moreover, the occupancy of traditional breeding sites across years in well-monitored Alpine populations varies a lot, this despite a relatively high breeding success at the population level. This raises concern about the long-term persistence of Alpine populations. Using conventional and satellite radiotracking, we investigated the spatio-temporal dispersal of 41 juvenile Eagle Owls originating from a population in the southwestern Swiss Alps. Our main goal was to determine dispersal distances, places and times of post-dispersal settlement. Juveniles left their parents between mid-August and mid-November. They covered, on average, 12.7km per night (linear distance between two consecutive day roosts), often crossing high mountain ranges (up to 3,000m altitude). The mean total distance covered by an individual during dispersal was 102km (sum of night movements), with a maximum of 230km. Settlement places were, on average, 46km distant from the birth place. Our study establishes long-distance dispersal in juvenile Eagle Owls, even in a complex topography, suggesting the existence of a wide-scale metapopulation system across the northwestern Alps. This metapopulation dimension should be accounted for in conservation plans