Resource Selection Patterns of Immature Eastern Hellbenders in North Carolina, USA

Abstract

The Hellbender (Cryptobranchus alleganiensis) is a giant salamander inhabiting streams in the eastern United States that has experienced range-wide declines. It is estimated that Hellbenders have declined by 70% in some portions of their range, and many populations are composed solely of older adults, suggesting that a lack of successful breeding or low larval survival may be driving some declines. Although successful reproduction and larval survival influence the long-term stability of Hellbender populations, little is known about the ecological requirements of immature age classes. Understanding the requirements of immature Hellbenders is essential for accurately gauging population health and designing long-term conservation efforts. The objective of our study is to investigate associations between immature Hellbender habitat use and abiotic factors hypothesized to influence survival. We quantified habitat selection of immature Hellbenders within a use/availability framework in six streams in North Carolina known to contain all Hellbender age classes. Our results suggest that immature Hellbenders select home ranges based on a reduced water velocity and the presence of unembedded cobble beds and, within that home range, select unembedded mid-sized cover (18–28 cm) as microhabitat. We recommend targeting immature age classes during monitoring surveys to ensure a complete understanding of a population's status. This can be accomplished by conducting targeted surveys in areas of the stream with a slower current and beds of heterogeneous, unembedded cobble. We also recommend considering habitat preferences of immature age classes when selecting sites for Hellbender reintroductions and designing stream restoration initiatives to benefit Hellbender populations.