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Abstract
Mojave Desert tortoise (Gopherus agassizii) populations have declined for decades, prompting the development of recovery tools. One conservation practice is head-starting,
and continued optimization, including reducing rearing duration and considering
tortoises’ response to climate, will foster broader and more effective implementation. We
released and radio-tracked 60 juvenile tortoises reared under two treatments: (1) rearing
one year indoors, then one year outdoors (“Combo-reared”), and (2) rearing indoors only
for one year (“Indoor-reared”). We quantified their behavior, movement, and first year
survival. We found no difference in behavior or survival between treatments, but combo
tortoises demonstrated higher site fidelity in their movements than indoor tortoises.
Additionally, using long-term tracking data of 324 juvenile tortoises released between
2012-2020, we investigated the relative role of husbandry treatment and climate on longterm survival, focusing on drought. We found increasing drought severity decreased
tortoise survival overall, and survival was not significantly different by head-starting
treatment.