Herman's tortoise, Testudo h. hermanni, is an endangered subspecies in Italy, France, and Spain. We studied a Herman's tortoise population in the Riserva Naturale Regionale Monterano in the Tolfa Mountains of central Italy. We found that, unlike most other studies of this and related species, sex ratios were 1∶1, and half the population was made up of juveniles. Sexual maturity was reached at 12 years in males and 12–13 years in females, and females were significantly larger. Tortoises greatly preferred open maquis habitat over other habitat types and thermoregulated so that body temperatures stayed consistently above ambient temperatures, especially under low ambient temperature conditions. Presence of ticks was significantly associated with an index of thermoregulatory behavior. We suggest that maintenance of open maquis habitat in this reserve is essential to high hatchling production and effective thermoregulation.