The role of birds in Late Pleistocene Eurosiberian-Mediterranean boundary reconstructions in Western Europe

Birds have been considered good climate indicators in Pleistocene environmental reconstructions, due to their current distribution and specific ecological requirements. They have been analyzed as associations and in some cases also as indicator species for the climate during the Late Pleistocene, which is a stage that shows strong climatic fluctuations. In this work we present an analysis of the relative abundances of thirty-three of these indicator species of Aves in Late Pleistocene Western European sites, in order to characterize the avian associations and bird species behavior, and also shed light on the corresponding ecosystems of the different geographical areas of Europe during this stage. Our analysis reveals four main groups of sites, which correspond mainly to the current biome distribution. Nevertheless, the position of some sites in the analysis is markedly different, revealing a drift southward of the Eurosiberian-Mediterranean boundary during the Late Pleistocene. The results also allow us to analyze the behavior of the various species, whose distributions seem to be controlled by the predominant vegetation in each area more than by the temperature. The different associations of each area suggest that Central Europe was forested or at least point to the presence of forest patches in this area at the end of the Pleistocene. They also reveal the need for avian association analysis instead of the use of isolated bird species to produce landscape and climate reconstructions.