Habitat preferences of Bonelli´s Eagles (Hieraaetus fasciatus) in Alicante (E of Spain) at two spatial scales

Authors: RICO ALCÁZAR, L., MARTÍNEZ, J. A., MORÁN, S., NAVARRO, J. R. and RICO, D.

E-mail: jmkaja@hotmail.com

Published: Volume 48(1), June 2001. Pages 55-62.

Language: Spanish

Original Title: Preferencias de hábitat del Águila-azor Perdicera (Hieraaetus fasciatus) en Alicante (E de España) a dos escalas espaciales

Keywords: Bonelli’s Eagle, conservation, habitat selection, modelling, raptors and scale

Summary:

We studied nesting and hunting habitat preferences of Bonelli’s Eagles in the province of Alicante. In the period between 1989 and 2000 we located all nests of the species in the study area, and their positions were translated to 1:25,000 topographic maps. Since ecological processes can be scale-dependent, we measured a series of variables (Table 1) at two different scales: in a circle of 2.8 km of radius centred on the most frequently used nest and in a second circle of 5.6 km of radius aimed at representing the Eagles’ home ranges. Due to the lack of information about the Eagle’s home range size, both scales were arbitrarily set. We compared land uses, relief and degree of human disturbance between occupied circles and non-occupied circles centred on suitable cliffs higher than 10 m selected at random. For analytical purposes, we used logistic regression models. Relief was the best predictor of nest locations at the 2.8 km-scale. At the 5.6 km-scale, we found that the surface of scrubland increased the probability of finding nests, while the surface of irrigated cultivation decreased that probability. Both models reduced low percentages of the variance of the null model, suggesting that the response of Bonelli’s Eagles to the variables was weak, that the scales, arbitrarily set, may not be biologically significant for the species, or both. We suggest that heavy and sustained persecution by man is a confounding factor when addressing the habitat preferences of the Bonelli’s Eagle in Alicante. The pattern of habitat preferences described here may not correspond with the distribution of resources that this large predator may be able to use in the absence of human persecution. Therefore, the process of habitat selection cannot be inferred from the current pattern of habitat preferences. We encourage radio-tracking studies to improve conservation strategies.

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