Collecting a sample of loggerhead sea turtle hatchlings before a natural emergence does not reduce nest productivity

Abstract

In numerous studies involving hatchling sea turtles, researchers have collected small numbers of hatchlings from nests a few hours before the turtles would otherwise have emerged naturally. This procedure makes it possible to do experiments in which the behavioral or physio- logical responses of numerous hatchlings must be tested in a limited period of time, and also allows hatchlings to be released back into the sea in time to migrate offshore before dawn. In prin- ciple, however, the procedure might inadvertently reduce nest productivity (the number of hatch- lings that successfully leave the nest), if digging into a nest prior to emergence somehow reduces the ability of the remaining turtles to emerge. We compared nest productivity in 67 experimental loggerhead nests, from which we removed 10 hatchlings before a natural emergence, to 95 control nests left undisturbed before a natural emergence. The 2 groups showed no statistical differences in productivity. We conclude that taking a few hatchlings from a loggerhead nest shortly before a natural emergence has no negative impact on hatchling production if sampling is done with care at locations where there are few nest predators, and at sites where an emergence can be predicted because nest deposition dates are known.