Post‐release movement and survivorship of head‐started gopher tortoises

Abstract

ABSTRACTGopher tortoise (Gopherus polyphemus) populations are declining throughout their range and recovery requires management intervention to alleviate losses. Population augmentation strategies may prove useful in recovery of depleted populations once threats are mitigated. We head‐started and soft‐released hatchlings produced from robust donor populations and evaluated their post‐release survivorship and movement for the first year following their release. During 2014 and 2015, we head‐started and released 145 tortoises, of which we radio‐tracked a subset of 41 individuals, from 2 cohorts at 2 release areas within Yuchi Wildlife Management Area in Burke County, Georgia, USA. Movement and mortality of gopher tortoises was highest in the first month after release but declined soon after. Estimated annual survivorship of our first cohort was 60.6%. Annual survivorship of our second cohort was low (7.1%) at the southeast release area but much higher (75.0%) at the northwest release area because of spatial variation in predation. Although survivorship was variable, site fidelity remained high throughout the study and no tortoise moved >122.0 m from its release location. Initial results suggest that head‐starting could prove effective as a population recovery tool, but that release strategy and predator mitigation, especially within the first month, are critical to success. © 2018 The Wildlife Society.