Does Temporal Variability of Winter Common Cranes in the Dehesas Depend on Farming Practices?

Abstract

The inclusion of Spain and Portugal within the European Community has brought about a change in the traditional farming practices in the dehesas of Iberia to intensive cereal and to irrigated crops. Here we use seven-year counts of Common Cranes in 38 wintering sites to evaluate whether habitat structure modified by farming practices in the Holm Oak (Quercus ilex) dehesas is an important determinant of variability in winter crane numbers. We extracted, from a set of nine variables that express different levels of human management in the Holm Oak dehesas, two factors that accounted for the 66% of the variance. The first factor was related to livestock utilization of the dehesas, while the second one reflected Holm Oak presence. We ran a general linear model to analyze the influence of farming practices (PC1 and PC2), landscape heterogeneity and roost site stability on inter- and intra-season variability in numbers of winter cranes. Livestock presence, Holm Oak presence, landscape heterogeneity and roost type stability did not explain intra- and inter- season variability in crane numbers wintering in the Holm Oak dehesas of Spain.