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1. Prebreeding, Courtship, and Mating Behaviors of Wild Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis)

   https://doi.org/10.1655/Herpetologica-D-23-00002  

   O'Brien, Rebecca SM; Groffen, Jordy; Dayer, Ashley A; Hopkins, William A (March 2024, Herpetologica)
2. Pre-breeding androgen and glucocorticoid profiles in the eastern hellbender salamander (Cryptobranchus alleganiensis alleganiensis)

   https://doi.org/10.1016/j.ygcen.2021.113899  

   Galligan, Thomas M.; Helm, Richard F.; Case, Brian F.; Bodinof Jachowski, Catherine M.; Frazier, Clara L.; Alaasam, Valentina; Hopkins, William A. (November 2021, General and Comparative Endocrinology)
3. Modulation of Paternal Care Behaviors in Response to Stream Conditions by Eastern Hellbenders ( Cryptobranchus alleganiensis alleganiensis )

   https://doi.org/10.1093/iob/obaf007  

   O'Brien, R_S_M; Groffen, J.; Dayer, A_A; Hopkins, W_A (February 2025, Integrative Organismal Biology)

   Synopsis The rapid environmental changes associated with the Anthropocene mean that flexible behavioral responses may be a critical determinant of animals’ resiliency to anthropogenic disturbance, particularly for species with long generation times and low vagility. One type of behavior that exemplifies this potentially important flexibility is parental care. Eggs and juvenile animals are sensitive to environmental stressors, and the ability of parents to adjust care behaviors to buffer their offspring from rapidly changing conditions may be critical to successful reproduction. In this study, we explore the role of parental care in buffering eggs from anthropogenic stressors in the long-lived, fully aquatic eastern hellbender salamander (Cryptobranchus alleganiensis alleganiensis). Using custom-designed infrared cameras installed in underwater artificial shelters in a natural stream, we describe hellbender paternal care behaviors in greater detail than has previously been possible, assess the extent to which hellbender fathers buffer their eggs from increasing levels of silt and decreasing concentrations of dissolved oxygen in nesting cavities, and describe the possible trade-offs that hellbender fathers exhibit between paternal care and self-maintenance behaviors. We found that while hellbender parents buffered their offspring from low dissolved oxygen concentrations by increasing parental care, there was an apparent trade-off between parental care and self-maintenance responses to low oxygen. Hellbender fathers did not show evidence of buffering their offspring from the effects of increasing silt or organic material in their nest cavities. We also found that filial cannibalism is a widespread behavior across nests, with almost all fathers exhibiting some cannibalism, although the extent varied widely. Our study indicates that hellbender parents may be able to reduce the impacts of declines in dissolved oxygen concentration on their offspring to a limited extent, but they may be unable to fully protect offspring from increasing silt. 

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4. Life-Stage Differences in Microhabitat Use by Hellbenders (Cryptobranchus alleganiensis)

   https://doi.org/0018-0831-75.1.21  

   Jeronimo G. Da Silva Neto, William B. (March 2019, Herpetologica)

   Hellbenders (Cryptobranchus alleganiensis) are long-lived, fully aquatic salamanders that inhabit cool, well-oxygenated streams and rivers in the eastern United States. Although once abundant, C. alleganiensis populations have experienced major declines across the historical range. Habitat degradation, siltation, aquatic contaminants, and infectious diseases are commonly suggested as contributors to these declines. Although Tennessee provides areas of high-quality habitat for C. alleganiensis, microhabitat differences among life stages are not well documented. We evaluated microhabitat use of larval, subadult, and adult C. alleganiensis at three streams in east Tennessee by comparing sites occupied by C. alleganiensis to random sites within each stream. We used multivariate analysis to evaluate microhabitat use differences among larval, subadult, and adult C. alleganiensis. We completed habitat assessments for 60 individuals. We detected an association between C. alleganiensis presence (regardless of life stage) and the percentage of large rock, the percentage of low embedded rocks, and the number of rocks above 500 mm. Furthermore, the volume of cover rock, the number of rocks above 500 mm, the distance to bank, and the percentage of low embedded rocks, gravel, and sand were the most important microhabitat attributes to discriminate life-stage distributions. Overall, our analyses identify microhabitat attributes that are potentially important for long-term C. alleganiensis conservation and provide guidance for stream protection and restoration practices that might mitigate sedimentation and habitat degradation in impacted streams. 

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5. Filial Cannibalism Leads to Chronic Nest Failure of Eastern Hellbender Salamanders ( Cryptobranchus alleganiensis )

   https://doi.org/10.1086/724819  

   Hopkins, William A.; Case, Brian F.; Groffen, Jordy; Brooks, George C.; Bodinof Jachowski, Catherine M.; Button, Sky T.; Hallagan, John J.; O’Brien, Rebecca S.; Kindsvater, Holly K. (July 2023, The American Naturalist)