Long distance navigation in albatrosses and sea turtles
In a number of studies, we explore how albatrosses and sea turtles cope with similar tasks, e.g. locating isolated breeding islands, homing to breeding sites on land compared with marine environments.
Using satellite telemetry and GPS loggers we will compare the migration and navigation of sea turtles in Southern Atlantic Ocean by the island of Ascension, with that of albatrosses by the islands of Crozet in the South Indian Ocean and Midway in the Pacific Ocean.
The Ascension green turtles (Chelonia myda) constitute a beautiful example of long-distance migration in open sea. In an international collaborative project, started 1998, we have studied the migratory movements and navigation performances of adult Ascension Island green turtles by using satellite transmitters to track migration and homing after displacement.
Our displacement experiments in which we captured and released the turtles in open ocean at different sites around Ascension Island have shown that successful returns occurred from north to northwest of the island, suggesting the turtles used cues transported by air or surface water, associated with this geographical direction. Here, a female green turtle on her way towards the sea after laying her eggs at Ascension Island.
Green turtle hatchlings heading towards the sea to begin their migration.
Albatrosses are avian masters of long-distance navigation in marine environments, and have adapted to return to isolated islands to breed. Their young are left to find the wintering areas on their own during their first migration as well as to locate the breeding island after many years at sea. Thus, we find many parallels with migration achievements in sea turtles.Despite this, very little is known about the first migration of albatrosses and even less about how their navigation system develops with age and which cues are involved during different parts of their lives. We have tracked the dispersal flights and first migration of young wandering albatrosses Diomedea exulans during several seasons, demonstrating very interesting patterns of movements and that young albatrosses cover mean distances corresponding to 4.6 turns around the earth during their first migration.