The Influence of Multiscale Habitat Variables and Population Density on Artificial Shelter Use by Hellbenders (Cryptobranchus alleganiensis)

Factors influencing the availability of artificial hellbender (Cryptobranchus alleganiensis) shelters in North Carolina, USA

“…We suspect that the extremely low rates of artificial shelter occupancy observed in our study may have been due to the relative abundance of natural shelter in our study reaches, a relatively low density of adult hellbenders, or some combination of the two. In a previous study, artificial shelter occupancy was maximized when per capita availability of natural cover was minimized, which occurred when hellbender abundance was relatively high and natural cover abundance was relatively low (boulder and bedrock; Bodinof Jachowski et al 2020, Button et al 2020 b ). While we made an effort to select stream reaches with hellbenders and minimal levels of natural cover, we found it particularly challenging to locate such stream reaches in our region.…”

“…Since initial development, artificial shelters for hellbenders have been used in at least 8 states to augment and improve habitat, soft–release captive bred individuals, collect eggs for head–starting and captive propagation, and facilitate minimally invasive monitoring (Messerman 2014, Bodinof Jachowski et al 2020). Most studies evaluating artificial shelter use have occurred in southwestern Virginia where, in the most successful stream reaches, over 80% of shelters may be occupied by adults on a single occasion (Bodinof Jachowski et al 2020) and approximately 24% of shelters are used for nesting each year (Button et al 2020 b ). Bodinof Jachowski et al (2020) and Button et al (2020 b ) found that adult hellbender density positively influenced rates of artificial shelter use in Virginia, especially when per capita natural shelter (i.e., large rock) availability is low and shelters function to supplemental an otherwise limited resource.…”

“…Most studies evaluating artificial shelter use have occurred in southwestern Virginia where, in the most successful stream reaches, over 80% of shelters may be occupied by adults on a single occasion (Bodinof Jachowski et al 2020) and approximately 24% of shelters are used for nesting each year (Button et al 2020 b ). Bodinof Jachowski et al (2020) and Button et al (2020 b ) found that adult hellbender density positively influenced rates of artificial shelter use in Virginia, especially when per capita natural shelter (i.e., large rock) availability is low and shelters function to supplemental an otherwise limited resource. However, work in Virginia has also shown that artificial shelters are vulnerable to destruction, dislodgement, and obstruction by sediment, making them intermittently unavailable to hellbenders, especially following seasonal peak discharge and high flows from major storm events (Bodinof Jachowski et al 2020).…”

Restoring eastern hellbender (Cryptobranchus a. alleganiensis) populations through translocation of headstarted individuals

“…For example, larval survival in natural settings and survival of young animals (between larval stage and first reproduction) are notoriously difficult to assess for cryptic species (Diaz et al, 2022; Foster et al, 2009). While some progress has been made in understanding the demography of early stages via monitoring wild hellbender nests in artificial nest boxes (C. Bodinof Jachowski et al, 2020; Briggler & Ackerson, 2012; Button et al, 2020; M. Kaunert, unpubl. data), we still lack basic natural history knowledge of this species or the threats to its persistence and their potential for mitigation.…”

Evaluating translocation success of wild eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) in Blue Ridge Ecoregion streams using pre- and post-translocation home range sizes and movement metrics

“…At each tracked location for each hellbender, we collected habitat data to test our hypothesis that cover object density and size would influence hellbender home range size and movements [ 42 ]. We defined “cover” as any substratum particle with at least one axis ≥ 26 cm and space underneath adequate for a hellbender refuge site [ 49 ]. We assessed cover object density by counting all available cover objects within a 2-meter radius of each hellbender location.…”