Local divergence between mediterranean crossbills occurring in two different species of pine

Abstract

Several studies have shown that different crossbill (Loxia curvirostra) populations inhabiting habitats dominated by different conifer species differ in bill morphology. The aim of this paper is to compare the bill morphology of crossbills inhabiting mountain (Pinus uncinata) and black pine (P.nigra) forests within the same geographical area in the Mediterranean where there is a high diversity of native pine species. We predicted that the large spines and thick apophyses of the mountain pine should favour crossbills with larger and more massive beaks.