Geomagnetic Imprinting and Natal Homing in Sea Turtles

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

The ability of animals to guide themselves unerringly during long-distance migrations has inspired both awe and envy in humans, who only recently, through global positioning technology, managed to equal the skills of elite animal navigators such as loggerhead sea turtles. These turtles leave their home beaches as hatchlings and migrate across entire ocean basins before returning years later to nest in the same coastal area where they originated. How adult turtles navigate to their natal beaches has remained enigmatic, but accumulating evidence suggests that turtles imprint on the unique geomagnetic signature of their natal beach and then use this information to return. The research will investigate the geomagnetic imprinting hypothesis using a multidisciplinary approach. Results will assist efforts to conserve animals such as sea turtles that undergo natal homing. For example, attempts to reintroduce sea turtles to geographic areas where they once nested have been largely unsuccessful because young turtles released in such areas seldom return as adults. An improved understanding of how turtles find their home beaches may help save these jeopardized species from extinction. Findings are also likely to reveal new modes of navigation that can be adapted for guidance systems of humans and autonomous vehicles. Broader impacts include providing research experience for undergraduate and graduate students, broadcasting findings into K12 classrooms through the North Carolina Museum of Natural History, and creating instructional web modules for K12 education, thereby enhancing both science education and public awareness of endangered sea turtles. The long-term objective of the research is to determine the behavioral and sensory mechanisms that underlie natal homing in sea turtles and other long-distance marine migrants. The research will test several central predictions of the geomagnetic imprinting hypothesis: (1) behavioral experiments will investigate whether nesting adult female turtles locate their natal beaches using the unique magnetic signature of their natal area; (2) statistical analyses will be used to determine whether the spatial distribution of turtle nests along continental coastlines is affected by fluctuations in Earth's magnetic field, as the geomagnetic imprinting hypothesis predicts; and (3) magnetic orientation behavior of turtle embryos prior to hatching will be studied to determine if imprinting might occur during development. Results and data will be disseminated primarily in scientific journals; when possible, appropriate data and metadata files will be posted in online supplementary materials or with services such as Dryad, which many journals now support.