At-sea distribution and behavior of streaked shearwaters (Calonectris leucomelas) during the nonbreeding period

Streaked Shearwaters (Calonectris leucomelas) breed in temperate regions of East and Southeast Asia and have been thought to migrate to tropical regions near the Equator after breeding. We documented the migratory and foraging behavior of this species using global location sensors (GLS). The GLS loggers were attached to 48 breeding birds in 2006 and were subsequently recovered from 38 birds in the following year. The Streaked Shearwaters migrated from the seas around Japan to three wintering areas in the tropics, the seas off northern New Guinea, the Arafura Sea, and the South China Sea (4,000, 5,400, and 3,500 km from the breeding colony, respectively). Most Streaked Shearwaters wintered off northern New Guinea, an area of low primary productivity but high Skipjack Tuna (Katsuwonus pelamis) abundance. Streaked Shearwaters flew for longer periods and landed on the water more frequently around dawn and dusk during the wintering period. This pattern of activity is similar to that of subsurface predators such as tuna, and to that of tropical seabirds that are known to feed with subsurface predators. We suggest that Streaked Shearwaters probably forage in association with subsurface predators in the tropical oceans during the wintering period. Foraging in association with subsurface predators and morphological adaptations for gliding may allow Streaked Shearwaters to forage efficiently in both temperate and tropical environments.

Details