Joint ringing efforts to unravel complex migratory patterns across ecological barriers: the potential of networking

Abstract

Ecological barriers represent a challenging and potentially risky component of migratory flyways. Complex patterns involve large arrays of species and huge numbers of birds in crossing deserts, mountain chains and large stretches of sea. Despite the recent rapid developments of new marking technologies, standardised ringing applied to networks of stations widely distributed across the barriers still represents a unique tool to unravel different aspects of the progression of the waves of migration. The Italian Ringing Centre at ISPRA co-ordinates two major projects investigating, respectively, songbird migration across the Mediterranean in spring and over the Alps in autumn. Networks of ringing stations provide details on geographical distribution of flyways based on first-capture data and on species-specific seasonality of movements as also explained by ecological factors acting both on the wintering and breeding grounds. Physical conditions of migrants at different stages of barrier crossing provide details on the energetic cost of endurance flights, contributing to the understanding of the ecological needs of migrants. Conditions of staging migrants, stopover duration and habitat use by migrants significantly contribute to the understanding of time- versus risk-minimizing strategies, within the general framework of the energetic balance of migration. Also, networks represented by the national communities of ringers contribute to the understanding of the ecological role a given country plays within larger migratory flyways. Ringing still offers great potential to analyse existing large-scale and long-term datasets to provide a sound scientific basis for the conservation of migrants.