Assessing the Efficacy of Translocation as a Conservation Strategy for Wild Eastern Hellbenders (Cryptobranchus Alleganiensis Alleganiensis) in Tennessee

Bradley D Nissen, Tennessee State University


Translocations have become a common conservation strategy for wildlife, yet they are not always rigorously monitored to evaluate their success. Due to population declines and habitat fragmentation throughout its range, the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) is a strong candidate for translocation in Tennessee. Our goal was to evaluate the short-term effects of translocation on wild hellbenders by comparing the 1) survival rates, 2) home range sizes, and 3) habitat usage of individuals pre- and post-translocation using radio-telemetry. We studied the spatial ecology and multi-scale habitat use of individuals (N = 27) in two sustainable populations (SS1 & SS2) for one year and then subsequently collected similar data from a portion of these individuals (N =17) that were translocated (May-July 2019) into two nearby streams (TS1 & TS2) with declining populations. We collected 1,571 location data points (849 prior to translocation and 722 post-translocation) from our four study sites. Survival rates of translocated hellbenders increased when moved from SS1 to TS1 (80% to 100%), while they decreased when moved from SS2 to TS2 (76% to 33%). Home range sizes increased from pre-translocation rates at both sites, but hellbender responses to translocation depended heavily upon physical characteristics of the release sites. Hellbender resource selection changed after translocation, with more importance on boulder availability. The increased importance of boulder densities on hellbender resource selection after translocation implies that large boulder clusters could serve as important cues for “suitable habitat” as hellbenders are attempting to assess new environments, and thus may promote site fidelity. Home ranges and fine-scale movement metrics indicated that hellbenders translocated from SS1 to TS1 settled in more quickly, had greater site fidelity, and smaller home ranges than hellbenders translocated from SS2 to TS2. The greater rate of “exploration” amongst hellbenders in TS2 could be due to lower boulder densities, and decreased prey availability, which may have led hellbenders to be more exposed to predation by otters. Our study found that translocations of wild hellbenders could be beneficial for regions where suitable habitat exists without healthy hellbender populations, especially if the populations have been extirpated or isolated from larger populations.

Subject Area

Conservation biology|Wildlife Conservation

Recommended Citation

Bradley D Nissen, "Assessing the Efficacy of Translocation as a Conservation Strategy for Wild Eastern Hellbenders (Cryptobranchus Alleganiensis Alleganiensis) in Tennessee" (2020). ETD Collection for Tennessee State University. Paper AAI28153007.