Assessment of Loggerhead Sea Turtle (Caretta Caretta) Nest Management Tools in South Carolina

This study reassessed the use of two current management tools utilized on nesting beaches statewide as part of the protection effort for loggerhead sea turtles, with a primary focus on South Carolina barrier island nesting beaches. The nest management tools assessed in this study include 1) the relocation of all nests laid seaward of the spring high tide line (SHTL) and 2) use of a probe stick to locate the nest cavity. The relocation of nests deposited seaward of the SHTL is a common management action that is to be used only as a last resort if the nest is presumably doomed in situ according to nest protection guidelines provided by the U.S. Loggerhead Recovery Plan and South Carolina Department of Natural Resources (SCDNR) Marine Turtle Conservation Program. While nest relocations are increasing due to a loss of suitable nesting habitat as beaches throughout the state face increased erosion, many of these relocations are unnecessary but are conducted due to the misconception of concerned project participants that the occurrence of any tidal wash-over will negatively influence hatch success (HS), even of nests marginally landward of the SHTL. The relationship between nest location, relocation, tidal influences (wash-over and inundation), and HS were examined. A sample of nests below the SHTL (low nests) were relocated to higher grounds while remaining low nests were left to incubate in situ. Nests deposited above the SHTL were monitored at their in situ nest sites at varying distances above the SHTL. This study determined if nests laid and/or relocated above the SHTL still have the potential to wash-over and/or inundate depending on the distance of the nest above the tide line, if relocation significantly increases HS when compared to in situ low beach nests, if HS varies based on distance of in situ and relocated nests from the SHTL (i.e. zone), and whether tidal events negatively impact HS (and if so, does this relationship vary across zones). Hatch success was significantly lower for in situ nests below the SHTL during the 2012 season, however, no discernible differences were identified between the HS of low nests when compared to in situ and relocated nests above SHTL during the 2013 season. Tidal wash-over significantly decreased the HS of low nests in 2012 and relocated nests in 2013 only. No relationship was evident between wash-over and the HS of in situ nests deposited above the SHTL. The ability of models to explain the relationship between wash-over frequency and HS greatly improved after addition of the predictor variable ‘storm-induced inundation/wash-away’. Results of this study indicate the majority of low beach nests produce viable offspring. During nest relocations, participants sometimes report eggs are found broken at the center or bottom of the clutch, but with no sign of direct puncture caused by the probe (i.e. yolk and/or albumen on the probe tip). Since the cause of breakage is unknown, these eggs are recorded as ‘broken in nest’ as opposed to the loss being attributed to probing. The goal of this study was to quantify egg loss associated with two nest location methods 1) probing and 2) hand digging the body pit to determine whether use of this tool is correlated with significantly higher loss and/ or decreased HS. Specifically, it was determined whether the number of eggs found broken inside nest cavities was significantly greater when using the probe to locate the clutch compared to an alternative method (hand digging) and whether nests found with the probe exhibit significantly lower HS. Hatch success did not vary between the methods. In addition, no eggs were found broken in nests located by hand digging the body pit during the 2012 or 2013 loggerhead nesting seasons, suggesting loss attributed to the probe is greater than previously quantified. Results of this study suggest a strong correlation exists between the use of the probe as a nest location method and the presence of broken eggs in a nest upon location, however, this study does not provide evidence for causation of eggs found broken during nest relocations with no sign of direct puncture