Migration cues and timing in leatherback sea turtles

Atlantic leatherback sea turtles migrate annually from foraging grounds off eastern Canada and the northeastern United States to southern foraging and breeding areas. Using Cox's proportional hazards model, we investigated the individual timing of the southward migrations of 27 turtles equipped with satellite-linked transmitters off Nova Scotia compared with turtle characteristics and satellite-measured ocean variables. Latitude, longitude, 1-week lagged average sea surface temperature, and 1-week lagged average chlorophyll-a concentration appear to influence the probability of departure. Higher temperature and, in the northern range of the study, higher chlorophyll concentration increased departure rates, perhaps due to the acceleration of the life cycle of the leatherback's gelatinous prey and/or increased feeding efficiency in these areas. This study highlights the opportunity to use satellite telemetry and environmental data to examine the cues for and timing of animal migrations and expands the study of migration timing to include a new species and environment. Copyright 2008, Oxford University Press.