Characteristics of burrows used by juvenile and neonate desert tortoises (Gopherus agassizii) during hibernation

Behavior of young tortoises released from seminatural nurseries could be affected by the length of time spent within the nursery before release. We tested whether neonate (under two months) and juvenile (8-9 years) Desert Tortoises selected hibernation burrows with differing characteristics after release from their natal pen. Burrow habitat (canopy cover and landscape slope) did not differ between age classes. Juvenile tortoises were larger than neonates and, therefore, used larger burrows than neonates, but their burrows were a closer fit to tortoise size than were the neonate burrows. Juvenile burrow orientation differed significantly from a uniform distribution, with a mean direction of 162° (SSE); the burrows of neonates were not oriented in any particular direction. Selectivity of juveniles compared to neonates may have contributed to higher levels of movement by juveniles between release and hibernation. These age-related differences in behavior should be incorporated into nursery-based management plans.