MODELLING NESTING HABITAT PREFERENCES OF EURASIAN GRIFFON VULTURE GYPS FULVUS IN EASTERN IBERIAN PENINSULA

Abstract

Aims: To apply modern habitat modelling techniques using generalized linear models approach to gen-erate not only explicative but also predictive habitat suitability models. Ecological factors that could af-fect the species ’ nesting habitat preferences at two spatial scales, one referred to the colony as a sam-pling unit and another trying to reflect the landscape level, had been underlined. Location: Castellón province, eastern Iberian Peninsula. Methods: Occupied and unoccupied cliffs and 10x10Km U.T.M. squares were compared using univari-ate tests. A generalized linear model, employing logistic regression, was applied to explain and predict the occurrence of Griffon Vultures at two spatial scales. In order to select the most parsimonious model amongst a set of logistic models built with different explanatory variables, the Akaike´s information criterion (AIC) was performed. With the aim of testing the predictive performance of the previously selected models, the threshold-independent Receiver Operating Characteristic (ROC) plot was computed. Results: 19 of 29 variables analyzed presented significant differences between occupied and unoccu-pied cliffs and between occupied and unoccupied squares. Colony parameters, climate, disturbance and vegetation variables, showed a good model performance in accordance with ROC plots and AUC. Despite geomorphological variables being significant on logistic model, model assessment techniques applied in