Mystery of the lowland Giant Hummingbirds (Patagona gigas) of central Chile
Andean hummingbirds have narrow elevational distributions (500-1,500 m in amplitude) as a result of their specialized hemoglobin, which is genetically optimized to bind oxygen at low atmospheric pressures (Graham et al. 2009; Projecto-Garcia et al. 2013). As such, few elevational generalist hummingbird species exist. The Giant Hummingbird (Patagona gigas) – the largest hummingbird in the world – defies this tendency. It is distributed from sea level to ~4,500 m in the Andes (Fernández et al. 2011), but it only occurs at sea level where the southern subspecies, P. g. gigas, breeds in central Chile (Estades et al. 2008). Furthermore, P. g. gigas is migratory and it does not winter at sea level. This raises the question: At what latitude and altitude do lowland Giant Hummingbirds winter?