| In 1989, D.J. Morafka began implementing his head-starting strategy for conserving desert tortoises at the US Army's Ft. Irwin by building large enclosures over natural habitat that were fenced and netted to exclude tortoise predators. Similar pens were subsequently built at Edwards Air Force Base and at Twentynine Palms Marine Base. Local wild adult female tortoises were moved inside temporarily in spring in time to prepare their nests in existing or new burrows and to donate their first clutch of eggs before being returned "home". Enclosed nests, eggs, hatchlings, yearlings and juveniles have long-term protection from predators along with natural foods, and young tortoises are given drinking opportunities (mimicking natural rainfall events) until they are large enough for likely survival to adulthood after release to the wild. Specific research projects that have been done by the UCLA group on enclosed young tortoises include measurements of burrow characteristics and preferences, winter activity and behavior, daily and annual food, energy and water requirements, diet, water budgets and dehydration rates under differing burrow conditions, shell hardening rates, multiple paternity frequencies, the influence of supplemental irrigation on juvenile growth, body condition and survivorship, post-release behavior, survivorship and mortality, and variation in head-started hatchling sex ratios. |