Icelandic Whimbrel first migration: Non-stop until West Africa, yet later departure and slower travel than adults

Migratory behaviour in young individuals is probably developed by using a complex suite of resources, from molecular information to social learning. Comparing the migration of adults and juveniles provides insights into the possible contribution of those developmental factors to the ontogeny of migration. We show that, like adults, juvenile Icelandic Whimbrel Numenius phaeopus islandicus fly non-stop to West Africa, but on average depart later, follow less straight paths and stop more after reaching land, resulting in slower travel speeds. We argue how the variation in departure dates, the geographical location of Iceland and the annual migration routine of this population make it a good model to study the ontogeny of migration.