Thermal effects of condominiums on a turtle beach in Florida

Beach temperatures at the depth of nests were studied at the loggerhead turtle Caretta caretta rookery at Boca Raton, Florida. The sand at 30 and 60 cm depth in areas shaded by condominiums averaged about 1°C cooler than that in adjacent areas unshaded by buildings. With particularly large condominiums, differences were as large as 2°C. Longer incubation durations of nests laid close to buildings were consistent with such sites being cooler. In the heat of midsummer, when temperatures on this beach were almost always well above the pivotal level, the shade from condominiums probably did not alter the sex ratio of the hatchlings. However, at the cooler start of the season, shade reduced temperatures to below the pivotal level, presumably increasing the number of males produced at this time.