Post-release Survivorship in a New Population of Blanding’s Turtles Established Using Headstarted and Directly Released Turtles

Jared M. Green^1,2,3,4, Stephanie L. Koch⁴, Kurt A. Buhlmann², Brian A. Bastarache⁵, Kourtnie A. Bouley^4,5, Brian O. Butler⁶, Richard B. Chandler³, and Tracey D. Tuberville^2,*

¹US Fish and Wildlife Service, Basking Ridge, NJ 07920. ²Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802. ³Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602. ⁴US Fish and Wildlife Service, Sudbury, MA 01776. ⁵Bristol County Agricultural High School, Dighton, MA 02715. ⁶Oxbow Associates, Inc., Boxborough, MA 01720. *Corresponding author.

Northeastern Naturalist, Volume 31, Special Issue 12 (2024): E68–E84

First published early online: 9 June 2024

Abstract
Emydoidea blandingii (Blanding’s Turtle) is a species facing a variety of anthropogenic threats that decrease population viability. We initiated a project to establish a new population of Blanding’s Turtles on a National Wildlife Refuge in Massachusetts using hatchlings obtained from a nearby, robust donor population. We released 440 headstarted individuals and 401 directly released hatchlings between 2007 and 2013 and conducted multiple years of post-release monitoring via aquatic trapping to estimate survival. Between 2014 and 2021, we released an additional 824 headstarted and 433 directly released individuals and conducted 1 year of aquatic trapping in 2021 to estimate population size. First year post-release survival of headstarted turtles was 6 times that of directly released hatchlings (0.72 vs. 0.12, respectively), but annual survival of both groups was 0.78–0.90 in subsequent years. Only 19% of turtles released at less than 60 mm carapace length (CL) were subsequently recaptured compared to 60% of those released at ≥60 mm CL, supporting 60 mm CL as a target minimum release size. The mean population estimates using 2 different study designs were 164 and 202, with 91 individuals encountered. Now that turtles released early in the project are approaching reproductive maturity, we recommend resampling and expanding trapping efforts to include more wetlands to assess long-term survival, abundance, and distribution of Blanding’s Turtles in this newly established population. Our results, combined with other evaluations of headstarting across the species’ range, add credence to the use of headstarting as a population-recovery tool for Blanding’s Turtles.

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