Linking processes: effects of migratory routes on the distribution of abundance of wintering passerines

Abstract

Movements of migratory birds across the Western Paleartic concentrate populations along Atlantic and Mediterranean coasts, thus producing flows of migrants that converge at both extremes of the Pyrenees. Here we analyse the effect of these corridors on the winter distribution of some passerines (F. Motacillidae, F. Turdidae and F. Fringillidae). The number of ring recoveries of migrants at the edges of the Pyrenees was higher than expected, a pattern that was also observed in the case of winter recoveries. In addition, there was a significant decrease in the abundance and species richness of the bird assemblages of the three families analysed wintering in the coastal farmlands of northern Iberian peninsula as their location was further away from the western corridor of the Pyrenees. These results suggest the existence of links between the routes of migratory passerines and their winter densities in northern Iberia.