Long-term resource use and foraging specialization in male loggerhead turtles

Abstract

Intra-population variation in resource use has been increasingly reported for different taxa. In particular, foraging specialization of individuals has been quantified for various generalist populations. Because individual differences in resource use can have a great effect on a population’s ecological and evolutionary dynamics, it is essential to accurately assess how individuals exploit resources. Recent studies have shown that female sea turtles exhibit long-term individual specialization in resource use. In this study, we used stable isotope analysis (δ15N and δ13C) of serially sampled sea turtle scutes from two foraging areas in the Northwest Atlantic to evaluate whether male loggerhead sea turtles (Caretta caretta) exhibit patterns in resource use over time similar to those reported for female turtles. We found that some male loggerheads show individual specialization and a long-term consistency in resource use over several years—which adds support to previous findings that male loggerheads exhibit site fidelity to their foraging areas—while others are less consistent or only exhibit consistency for shorter periods of time. This variation in patterns of resource use among male loggerheads appears to be linked to foraging area locations, which were characterized by distinct resource diversity. Thus, these results suggest that resource diversity (habitat and prey items) present at the foraging areas may affect the degree of temporal consistency in resource use and potentially individual foraging specialization in loggerheads. Understanding the drivers of intra-population variation in resource use in loggerheads will allow us to predict how they will respond to changing environmental conditions.