Files
Abstract
Mojave desert tortoise populations are in decline and improving juvenile survival pre-release (head-starting) is being evaluated to augment populations. We released three treatment groups to evaluate the potential of combination head-starting. Treatment groups consisted of tortoises reared outdoors for 6-7 years (n = 30), outdoors for two years (n = 24), or indoors for one year followed by outdoors for one year (‘combination head-started’; n = 24). Combination head-starts were smaller than 6-7-year-old outdoor reared animals at release, and both groups were significantly larger than animals reared solely outdoors for two years. All treatment groups had nearly identical body conditions, while two-year-old outdoor animals had significantly softer shells than either of the other treatments pre-release. Combo head-starts exhibited strong post-release site-fidelity in comparison to the solely outdoor reared treatments. Size was a significant predictor of survival, with combo head-starts and 6-7-year-old outdoor head-starts exhibiting particularly high survival rates 10-months post-release.