Migratory shearwaters integrate oceanic resources across the Pacific Ocean in an endless summer

Abstract

Electronic tracking tags have revolutionized our understanding of broad-scale movements and habitat use of highly mobile marine animals, but a large gap in our knowledge still remains for a wide range of small species. Here, we report the extraordinary transequatorial postbreeding migrations of a small seabird, the sooty shearwater, obtained with miniature archival tags that log data for estimating position, dive depth, and ambient temperature. Tracks (262 ؎ 23 days) reveal that shearwaters fly across the entire Pacific Ocean in a figure-eight pattern while traveling 64,037 ؎ 9,779 km roundtrip, the longest animal migration ever recorded electronically. Each shearwater made a prolonged stopover in one of three discrete regions off Japan, Alaska, or California before returning to New Zealand through a relatively narrow corridor in the central Pacific Ocean. Transit rates as high as 910 ؎ 186 km⅐day ؊1 were recorded, and shearwaters accessed prey resources in both the Northern and Southern Hemisphere's most productive waters from the surface to 68.2 m depth. Our results indicate that sooty shearwaters integrate oceanic resources throughout the Pacific Basin on a yearly scale. Sooty shearwater populations today are declining, and because they operate on a global scale, they may serve as an important indicator of climate change and ocean health.avian migration ͉ diving behavior ͉ habitat use ͉ sooty shearwater ͉ tracking

Individual variability in the migratory path and stopovers of a long-distance pelagic migrant

“…Spatiotemporal variation in wind strength and direction can shape not only the routes followed by birds, resulting in the well-known 'figure-of-eight' path of some transequatorial migrants (e.g. Shaffer et al 2006;González-Solís et al 2007), but also the timings of migration (Felicísimo et al 2008). This dependence on wind conditions is closely related to the type of flight adopted.…”

“…Shaffer et al 2006;González-Solís et al 2007;Guilford et al 2009;Dias et al 2012a). Like other pelagic migrants, shearwaters are often faithful to their wintering sites in successive years Raine et al 2013), but so far no studies have addressed their year-to-year fidelity in routes and stopovers.…”

Lost at sea: genetic, oceanographic and meteorological evidence for storm-forced dispersal

“…climate) that may have consequences for migratory behaviour and species survival [6]. It is therefore suggested that global migrators, such as transoceanic migratory birds, may be useful as biological indicators of climate and oceanic health [7].…”

Breeding latitude drives individual schedules in a trans-hemispheric migrant bird

“…Studies are oft en limited to methods (for example, stable isotopes) that require indirect steps to link the breeding and non-breeding grounds of individual birds. Th e advent of small, lightweight geolocators allows these links to be made directly 12 , but the need to retrieve units to access data has limited their use to site-faithful species using accessible, high-density breeding sites 13,14 . Bar-tailed godwits breed cryptically in low densities across over 1,800 km of remote coastal tundra within Alaska 10 , making breeding studies extremely diffi cult.…”