Annual variations in the migration routes and survival of pelagic seabirds over mountain ranges.

Pelagic seabirds have evolved physiological and morphological characteristics that enable them to fly in an energy efficient manner over the oceans. Although there are some exceptions (e.g., Delord et al. 2020), most species come ashore only to breed or rest. However, recent tracking technologies have revealed some unexpected overland journeys. For example, brown pelicans Pelecanus occidentalis (Lamb et al. 2017), Arctic terns Sterna paradisaea (Redfern & Bevan 2020), and the focal species of this study, fledglings of streaked shearwaters Calonectris leucomelas (Yoda et al. 2017a; Fig. 1a), are known to migrate overland.