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

Diaz, Lauren; Unger, Shem D.; Williams, Lori A.; Jachowski, Catherine M. Bodinof

doi:10.1643/h2020050

Cited by 5 publications

(5 citation statements)

References 37 publications

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“…Although VIE tags have occasionally been used to mark hellbender larvae in the wild (Hecht-Kardasz et al, 2012;Pugh et al, 2013Pugh et al, , 2016, our understanding of retention and readability over time was poorly understood. Diaz et al (2022) reported the first confirmed recapture of a VIE-tagged immature hellbender in the wild using the techniques in our study, which occurred approximately 3 wk following initial capture and tagging. Our findings build upon these anecdotal reports by providing quantitative evidence that VIE tags are highly likely to remain detectable even 1 full yr posttagging.…”

Section: Discussionmentioning

confidence: 72%

“…Although Fouilloux et al (2020) successfully used VIE tags to identify small larval anurans, the safety and efficacy of VIE-tagging has not been demonstrated with larval hellbenders. A lack of unique identifiers has also potentially hindered our understanding of basic hellbender ecology and conservation because information such as larval abundance, survival, and dispersal remains unclear (Bodinof Jachowski and Hopkins, 2018; Diaz et al, 2022).…”

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confidence: 99%

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Long-term Retention, Readability, and Health Effects of Visible Implant Elastomer (VIE) and Visible Implant Alpha (VI Alpha) Tags in Larval Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis)

Knapp,

Diaz,

Unger

et al. 2023

Journal of Herpetology

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The ability to identify individuals is essential for determining population demographics of a species, but traditional marking techniques, such as passive integrated transponder tags, are often limited to individuals that meet minimum size thresholds. Visible implant elastomer (VIE) and visible implant alpha (VI Alpha) tags are promising methods for marking small-bodied individuals. However, the efficacy and health effects of VIE and VI Alpha tags are not established for many, increasingly imperiled, herpetofauna. Over a 12-mo period, we examined tag retention, tag readability, VIE tag color readability, and effects on growth and body condition of VIE and VI Alpha tags in larval Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis), a species of conservation concern. We observed 100% retention of VIE tags and 80% retention of VI Alpha tags over 1 yr. Readability degraded over time for both tag types but was consistently higher for VIE relative to VI Alpha tags. Degradation in readability over time increased our reliance on a 450-nm-wavelength VI light to read VIE tags but had more severe implications for VI Alpha codes, which were illegible after 4 mo. Pink- and green-colored VIE tags performed similarly well and we found that neither VIE nor VI Alpha tags negatively affected growth or body condition of larval hellbenders. Our findings collectively suggest that VI Alpha tags are an unviable tagging method, but VIE tags were safe and effective for identifying unique larval hellbenders up to 1 yr.

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Section: Discussionmentioning

confidence: 72%

mentioning

confidence: 99%

Long-term Retention, Readability, and Health Effects of Visible Implant Elastomer (VIE) and Visible Implant Alpha (VI Alpha) Tags in Larval Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis)

Knapp,

Diaz,

Unger

et al. 2023

Journal of Herpetology

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“…This particular analysis is subject to assumptions related to natural survival rates of various age classes, some of which can only be inferred from prior studies (Unger et al, 2013). 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.…”

Section: Discussionmentioning

confidence: 99%

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

Kaunert,

Brown,

Spear

et al. 2023

Population Ecology

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Freshwater biodiversity is declining at a fast pace despite significant efforts directed toward the management and conservation of aquatic systems. Eastern hellbenders are one of North America's most iconic stream amphibian species, a sentinel of stream health, and are experiencing rapid population declines throughout most of their range. Common conservation strategies include headstarting; however, the success of this strategy for rebuilding hellbender populations and the most optimal release scenarios have largely been unassessed. We use a cohort of 205 animals released in several Ohio watersheds to evaluate the success of headstarting and reintroduction efforts over 3 years. Using PIT‐tag surveys over 25 occasions between July 2018 and November 2021 and capture–recapture models, we found that 3‐year apparent survival post‐release was 0.162 ± 0.061, with lower survival in year 1 (0.383 ± 0.058) and greater in years 2 (0.696 ± 0.086) and 3 (0.609 ± 0.154). Using demographic simulations, we found that releasing cohorts of N = 100 individuals at fewer suitable sites several times (e.g., 3 releases, 2 or 3 years apart) would be a better strategy compared to single release events across multiple sites. Additional simulations showed that eastern hellbender headstarting programs using wild eggs can be highly beneficial in producing more animals reaching adulthood (up to 7 times, if survival in captivity is assumed to be 100%) compared to development in the wild. This study emphasizes the need to monitor the success of reintroduction programs and provides evidence that headstarting can be a viable strategy for rebuilding eastern hellbender populations.

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“…We made the decision to redeploy shelters in a new suite of streams in 2019 after we failed to detect any hellbenders using our shelters in 2018, and after failing to detect any hellbenders under natural cover objects during post–hoc surveys to determine possible explanations for the complete lack of artificial shelter use. Briefly, post–hoc surveys were aimed at confirming presence of adult hellbenders via rock–lifting while snorkeling, passive snorkeling surveys during the breeding season, and searching cobble for larvae (Nickerson and Krysko 2003, Diaz et al 2022). The three streams that were the focus of our study in 2019 were selected because state biologists had visually detected several adults in each stream during recent passive breeding season surveys, though precise estimates of hellbender density were still unavailable (Table S2).…”

Section: Methodsmentioning

confidence: 99%

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

Diaz

Unger

Williams

et al. 2022

Wildlife Society Bulletin

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The hellbender (Cryptobranchus alleganiensis) is a fully aquatic giant salamander experiencing population declines throughout the eastern United States. Hellbender declines are likely due to a loss of cover and breeding habitat, therefore artificial shelters have been designed for hellbenders to supplement breeding habitat and monitor reproductive success. Although several artificial shelter designs are currently in use throughout the hellbender range, no previous study has compared different designs in the field. We compared three shelter designs (modified boot design with an open bottom, modified boot design with a closed bottom, and a modified hydrodynamic design) to estimate their probability of availability (remaining in place and not obstructed by sediment) to hellbenders during variable stream conditions. We deployed 180 shelters of the three designs (n = 60 each) across six stream reaches in western North Carolina, measured habitat variables at installation points, and monitored shelters for sediment blockage, dislodgement, and hellbender occupancy. Shelter availability averaged 71% across all sampled occasions (67% modified boot closed, 69% modified boot open, 77% modified hydrodynamic). Blockage of shelters by sediment was responsible for the majority (96%) of occasions when shelters were deemed unavailable. Hellbenders rarely (range = 0 to 11% of occasions per site) used artificial

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

Cited by 5 publications

References 37 publications

Long-term Retention, Readability, and Health Effects of Visible Implant Elastomer (VIE) and Visible Implant Alpha (VI Alpha) Tags in Larval Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis)

Long-term Retention, Readability, and Health Effects of Visible Implant Elastomer (VIE) and Visible Implant Alpha (VI Alpha) Tags in Larval Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis)

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

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

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