Nesting leatherback sea turtle (Dermochelys coriacea) packed cell volumes indicate decreased foraging during reproduction

Abstract

Leatherback sea turtles (Dermochelys coriacea) are hypothesized to be capital breeders, whereby they forage little to none during the nesting season. The capital breeding hypothesis can be tested in marine turtles using physiological measures of health, which are much less expensive than studies that use satellite tags or other physiological monitoring equipment to make inferences about behavior and foraging status during the nesting season. In this study, we analyzed packed cell volumes (PCVs), a simple and inexpensive, hematologic health parameter, in nesting leatherback turtles from St. Croix, U.S. Virgin Islands (17°40′40″N, 64°54′0″W) across the nesting season (April–July 2009) in an effort to determine foraging status. We found that PCV in nesting females significantly declined using two longitudinal measures: nest number and level of reproductive effort. We also found that PCVs of remigrants were significantly higher in comparison with neophytes, suggesting that experience in reproductive activities (e.g., migration, breeding, nesting) might increase foraging success on feeding grounds. Lastly, we found that leatherbacks with a greater reproductive output had significantly higher PCVs. While the northwest Atlantic leatherback population is evaluated as least concern by the IUCN, Pacific leatherbacks are critically endangered. The assumed behaviors of turtles from this study provide insight into reproductive strategies and energy reserves in all marine turtle populations. Thus, the results presented here are applicable to (1) veterinarians, rehabilitation facilities, and conservationists and (2) other more vulnerable marine turtle populations.