Migration cues and timing in leatherback sea turtles

Atlantic leatherback sea turtles migrate annually from foraginggrounds off eastern Canada and the northeastern United Statesto southern foraging and breeding areas. Using Cox's proportionalhazards model, we investigated the individual timing of thesouthward migrations of 27 turtles equipped with satellite-linkedtransmitters off Nova Scotia compared with turtle characteristicsand satellite-measured ocean variables. Latitude, longitude,1-week lagged average sea surface temperature, and 1-week laggedaverage chlorophyll-a concentration appear to influence theprobability of departure. Higher temperature and, in the northernrange of the study, higher chlorophyll concentration increaseddeparture rates, perhaps due to the acceleration of the lifecycle of the leatherback's gelatinous prey and/or increasedfeeding efficiency in these areas. This study highlights theopportunity to use satellite telemetry and environmental datato examine the cues for and timing of animal migrations andexpands the study of migration timing to include a new speciesand environment.