Orientation of the gopher tortoise, Gopherus polyphemus

Twenty-three gopher tortoises were released in an open field at least 8 km from their home burrows, and thirty-seven were tested in an arena which excluded all directional landmarks. Over half showed a statistically significant individual direction preference under each of these conditions. Directions chosen had no relation to the homeward direction and were widely divergent for individuals from the same geographic population. Comparing the preferred directions in the open field and in the arena indicates that landmarks may have a disruptive effect on orientation. The preferred headings of ten tortoises subjected to a 6-hr phase shift was about ninety degrees in the expected direction, indicating that this species is capable of sun-compass orientation.