Foraging ecology of oceanic-stage loggerhead turtles Caretta caretta

Abstract

We examined stomach contents (n = 12) and fecal samples (n = 4) in the first quantita- tive analysis of diet composition of oceanic-stage loggerhead turtles Caretta caretta from the North Atlantic Ocean. We found that loggerheads from the Azores are opportunistic carnivores that feed upon a variety of oceanic and pelagic organisms; our results also show that they exploited novel food resources, such as non-indigenous species. The diversity of prey species was positively correlated with loggerhead body size and volume of stomach contents. Because loggerhead body size was also positively correlated with stomach content volume, we were unable to determine whether increased prey diversity was a result of turtle foraging behavior or simply due to a larger sample volume from larger turtles. Ecological associations among prey species increase the diversity, and possibly the nutritional quality, of prey items, and periodic meteorological events can also increase the diversity of prey items available to loggerhead turtles. Aspects of the life history of some of these prey organ- isms, such as continued egg brooding, increase the nutritional value of prey items consumed by juve- nile turtles.