The reintroduction of migratory Northern Bald Ibises (Geronticus eremita) in Central Europe has been successfully running for over 20 years. The population now consist of more than 200 individuals with breeding colonies north and south of the Alps. They have been reproducing since 2011 and by now 250 offspring have fledged in the wild.
The birds are regularly migrating to a common wintering site in Tuscany, Italy. However, we have observed that autumn migration starts progressively later over the years. This trend, obviously exogenously induced and directly related to the increasingly extended autumnal warm spells, causing more and more birds from the Northern Alpine Foreland to fail in crossing the mountain barrier. We ultimately have to capture and transfer them to the southern edge of the mountains, to avoid significant losses during winter.
Thus, climate change is increasingly threatening the autonomous survival of the colonies north of the Alps. Our mitigation strategy is to significantly expand the project. In 2023, we start establishing a second migration route without the Alpine barrier over 2.300 kilometres to a wintering site in Andalusia, Spain, in the area of another sedentary release population (Proyecto Eremita). Human-led migration is used as the release method. The fusion with the Andalusian birds should eventually lead to a pan-European population which can react with greater flexibility to the consequences of climate change.
The measures and experiences of this long-lasting European project provide important implications for other translocation projects in times of climate change.