Hellbender Ecology in North Carolina: A Comparison of Artificial Cover Designs and Evaluation of Larval Resource Selection
Date of Award
Master of Science (MS)
Forestry and Environmental Conservation
Catherine Bodinof Jachowski
The hellbender (Cryptobranchus alleganiensis) is a giant salamander inhabiting streams in the eastern United States. Hellbenders have experienced range-wide declines due to a loss in population recruitment. It is unclear whether the loss in recruitment stems from a loss of nesting or larval habitat. Artificial shelters have been developed as a tool to supplement nesting habitat for hellbenders, however their use requires further investigation to be implemented effectively. Furthermore, once larvae emerge from the nest, there is a dearth of information regarding larval ecological requirements. My objectives were to 1) compare three artificial shelter designs in terms of their resiliency to the stream environment and hellbender preference, and 2) investigate resource selection patterns of immature eastern hellbenders. To compare artificial shelter designs, we deployed and monitored three shelter designs in North Carolina, collecting information on stream habitat, shelter state, and shelter occupancy. We recorded high rates of shelter unavailability due to sediment blockage, although the hydrodynamic shelter design performed best overall. We recorded low shelter occupancy rates and were unable to detect differences in hellbender preference. We recommend using they hydrodynamic shelter in larger rivers with more episodic high discharge events, and when installing shelters of either design, avoiding areas of the stream channel characterized by sediment deposition. To investigate resource selection patterns of immature hellbenders, we surveyed for hellbenders ≤ 200 mm in total length throughout three watersheds in western North Carolina and compared used and available habitat features at two spatial scales. We found that immature hellbenders select areas within the stream channel with a slower current and heterogenous, unembedded cobble beds as home ranges, and within those home ranges, select unembedded mid-large cobble. The habitat features preferred by immature hellbenders should be targeted during monitoring surveys and included in population restoration measures in order to effectively manage hellbender populations.
Diaz, Lauren, "Hellbender Ecology in North Carolina: A Comparison of Artificial Cover Designs and Evaluation of Larval Resource Selection" (2020). All Theses. 3272.