Advanced Autumn Migration of the Common CraneGrus grusOver Western Pyrenean Passes

Abstract

We investigated whether a large-bodied migrating bird, the Common Crane, has changed its migration phenology in response to climate change. For this, we used data collected at one of the most important convergence points of western European migration routes, the Western Pyrenees, in France. Phenological shifts were computed separately for three mountain passes, where daily counts of Common Cranes were collected for 29, 23 and 22 years, respectively. We analyzed trends in phenological shifts during each period and tested the influence of local and large-scale meteorological variables both in Pyrenees and on cranes' breeding areas on autumn migration dates. We found a similar and strong advance of phenology (20 days in 30 years) in Common Cranes passing the Western Pyrenees and this despite local variations in meteorological conditions. The increase in spring temperatures at northern latitudes, which could affect both spring migration and timing of breeding, as well as the variations in local winds in the Western Pyrenees were correlated with the phenological shift. We provided evidence that this large-bodied species is able to advance his autumn migration, similarly to small-bodied passerines.