Nest-site selection by the Eagle Owl Bubo bubo in semi-arid Mediterranean habitats.

Authors: MARTÍNEZ, J. E. and CALVO, J. F.

Published: Volume 47(2), December 2000. Pages 215-230.

Language: Spanish

Original Title: Selección de hÁbitat de nidificación por el Búho Real Bubo bubo en ambientes mediterrÁneos semiÁridos

Keywords: Bubo bubo, limiting factors, nest-site selection, semi-arid habitats and southeastern Spain.

Summary:

The factors presumably limiting Eagle Owl distribution in a semi-arid Mediterranean habitat (Murcia Region, southeastern Spain) were studied. Habitat features of 46 cliffs were characterized, incluiding cliffs with nests (n = 23) and cliffs where the species has never been detected (n = 23). For each cliff, 14 variables evaluating habitat humanisation, phisiography, vegetation, intraspecific competition and prey availability were quantified (Table 1). Eagle Owls selected smaller cliffs of lower accessibilty and located on less step slopes than those available (Table 2). This selection could be related to the optimization of the energetic costs of hunting. We observed negative relationships between cliff height and variables measuring habitat humanisation. In the semi-arid habitats considered here, the main limiting factor for Eagle Owl settlement seems to be the presence of conspecifics, a fact that is probably related to the high density of Eagle Owls (Table 2). Variables related to vegetation types, prey availability and habitat humanisation around cliffs did not differ between sites either occupied or unoccupied by Eagle Owls (Table 2). Our results differ from previous studies carried out in northern Spain, where Eagle Owl distribution seems to be limited by the availability of European rabbits Oryctolagus cuniculus as well as by human disturbance (Donázar, 1988).

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