Estimating the effect of beach nourishment on Caretta caretta (loggerhead sea turtle) nesting

Caretta caretta (loggerhead sea turtle) nesting activity was recorded daily during three seasons prior to and two seasons immediately following a beach nourishment (replenishment) project in Palm Beach County, Florida. Surveys were done at the nourished beach (Jupiter/Carlin) and at two natural beaches (Juno and Tequesta). The size of the nourishment effect on nesting activity was estimated using Before-After-Control-Impact Paired Series (BACIPS) models. Nesting declined by 4.4 to 5.4 nests km(-1) day(-1) on the nourished beach compared to the two natural beaches in the first season after nourishment. At the same time, false crawls (FC, non-nesting crawls) increased by 5.0 to 5.6 FC km(-1) day(-1) on the nourished beach. In the second season following nourishment, nesting was reduced by 0.5 to 1.6 nests km(-1) day(-1) on the nourished beach compared to the two natural beaches. The increase in false crawl frequency in the second season following nourishment was 0.7 to 0.9 FC km(-1) day(-1). These results suggest that beach nourishment significantly decreased loggerhead sea turtle nesting during the first season following the project. However, the size of the effect, in terms of nesting frequency and false crawl frequency, was much reduced by the second season following nourishment.