Few details are available on the migration (rates, routes, dates) of Neotropical austral migrant birds, which breed and migrate wholly within South America. Only one long-distance austral migrant breeds in the South American temperate forest biome: the White-crested Elaenia (Elaenia albiceps chilensis). However, the migratory dates, routes, and wintering locations are poorly known. During the austral summers of 2011–2013, we attached light level geolocators to breeding White-crested Elaenias at the world’s southernmost forests, on Navarino Island, Chile. The duration of fall migration of three Elaenias to the Amazonian wintering grounds was 64–96 days, while spring migration was 45–60 days. The average distance between breeding and wintering grounds was 5,932 km, which constitutes the longest migration of a Neotropical austral migrant studied to date. A better understanding of the annual cycle of Elaenias could offer new opportunities to examine the evolution of migration and population regulation of one of Patagonia’s most common birds.