North American Giant Salamanders (Cryptobranchus alleganiensis), commonly known as hellbenders, have been experiencing a population decline for decades due to human influences, such as pollution and habitat destruction. Many efforts are underway to save the hellbender but their entire potential geographical range has not been well-studied. Currently, hellbender populations are delineated by county boundaries and are on the International Union for Conservation of Nature Red List. The Genetic Algorithm for Rule-set Production, an Ecological Niche Model, was used to model the current hellbender potential distribution at a macro-scale under two different environmental scenarios. Additionally, future potential distributions were projected under two different climate change scenarios (Representative Concentration Pathways) to predict where possible habitat loss and expansion may occur in coming decades. Niche modeling was also used to evaluate the influence of environmental parameters across geography and between two sub-species of hellbender, the Eastern hellbender and the Ozark hellbender. Results showed that vegetation indices had some influence on current distribution predictions, while future models revealed that potentially large areas of currently suitable habitat may be lost, especially in the Ozark Mountains and the Southern Appalachian Mountains. Habitat expansion was predicted for several areas in the New England region of the northern Appalachian Mountains. The most influential variables were the maximum temperature of the warmest month, temperature annual range, and annual precipitation, while slope and elevation were less influential. However, areas of very high slope and elevation were not suitable for hellbenders, confirming previous descriptive habitat analyses. Current and future modeled distributions will provide conservationists with a more specific, and quantified, geographical and ecological description of where environmentally suitable areas exist for hellbenders. Micro-scale, stream-based studies provide areas of future research.

Understanding how species respond to anthropogenic changes and why species respond in the way that they do can help focus conservation planning. Hellbenders (Cryptobranchus alleganiensis) are a freshwater species of increasing conservation concern that are suspected to have declined due to loss of forest cover. However, quantitative evidence of land use effects on hellbenders is lacking. I used a multilevel approach to understanding whether hellbenders respond to land use by examining physiological indices, demographics and patterns of species occurrence as endpoints. My study area included two major river drainages in Virginia which mark a largely understudied portion of the species' range. In Chapter I, I described hellbender distribution and tested the hypothesis that hellbenders would be more likely to occur in heavily forested landscapes. Surprisingly, hellbenders occupied a relatively wide land use gradient (range = 50-90% forest in an upstream catchment) and current land use was an unreliable predictor of occurrence. In Chapter II I examined hellbender abundance and demographics at a subset of study sites stratified across a land use gradient. Abundance of sub-adult/adult hellbenders increased as forest cover increased in collective upstream riparian areas, primarily as the result of increased recruitment of new adults to local populations (rather than increased apparent survival of adults). Populations in lesser forested areas were declining and composed largely of relatively old adults, indicating that land use can lead to changes in hellbender distribution given sufficient time. In Chapter III, I examined three indices of physiological condition (body condition, hematocrit and leukocyte profiles) in hellbenders captured across a land use gradient. I found evidence suggesting low reproductive success may explain reduced recruitment in areas of low forest cover and evidence suggesting hellbender endocrinology during the breeding season may vary with land use. In Chapter IV I examine efficacy of artificial shelters as a monitoring tool and demonstrate their potential as tool to further our understanding of mechanisms underlying demographic responses of hellbenders to land use. I synthesize my findings in Chapter V and conclude that loss of forest cover in riparian areas poses a formidable threat to hellbender population viability in Virginia. / Ph. D.

Artificial shelters show great promise as novel, non-invasive tools for studying hellbenders, but their use thus far has faced several challenges. During initial trials in multiple river networks, artificial shelters routinely became blocked by sediment and dislodged during high stream discharge events, and were rarely used by hellbenders. We sought to determine whether these complications could be overcome via alternative shelter design, placement, and maintenance. Between 2013 and 2018, we deployed 438 artificial shelters of two different designs across ten stream reaches and three rivers in the upper Tennessee River Basin. We assessed evidence for several hypotheses, postulating broadly that the availability, stability, and use of artificial shelters by hellbenders would depend on how shelters were constructed, deployed, and/or maintained. We found that maintaining shelters at least once every 40 days limited sediment blockage, and building ~ 40 kg shelters with 3-4 cm thick walls and recessed lids improved their stability during high discharge events. Additionally, we found that hellbenders most frequently occupied and nested in artificial shelters when they were deployed in deeper (~50+ cm) portions of reaches with high adult hellbender densities. Our results suggest that artificial shelters can serve as effective tools for studying hellbenders when designed, deployed, and maintained with these advancements, but also highlight some limitations of their use. / Master of Science / Hellbenders are large, fully-aquatic salamanders that live primarily in cool, rocky, swift-flowing streams in portions of Appalachia and the lower Midwest. They are imperiled across most of their native range due to human-caused habitat degradation, but their declines, conservation needs, and population status have historically been difficult to study due to the fact that they spend the majority of their lives beneath large, often inaccessible boulders. While these boulders are sometimes possible to lift, doing so can disturb critical hellbender habitat. Therefore, alternate, less invasive hellbender sampling methods are necessary in order to improve knowledge about their conservation status and needs. Artificial shelters, which are large, hollow, concrete structures that mimic natural boulder crevices and feature removable lids, show promise as a novel, innovative tool for non-invasively studying hellbenders. However, initial trials of these shelters have yielded mixed results, with shelters often becoming swept away and destroyed during floods, becoming blocked by sand and sediment and thus inaccessible to hellbenders, or simply not being used by hellbenders when accessible. We sought to determine whether these complications could be overcome by optimizing the way that shelters were constructed, deployed, and maintained in streams inhabited by hellbenders. Between 2013 and 2018, we deployed 438 artificial shelters of two different designs across ten stream reaches and three rivers in the upper Tennessee River Basin. Using multiple analyses, we tested one broad overall hypothesis: that the efficacy of using artificial shelters to study hellbenders would depend on how they were constructed, how frequently they were maintained, and where they were placed in the stream. We found that maintaining shelters at least once every 40 days limited sediment blockage, and building ~ 40 kg shelters with 3-4 cm thick walls and recessed lids improved their stability during flood events. Additionally, we found that hellbenders most frequently occupied and nested in artificial shelters when they were deployed in deeper (~50+ cm) portions of reaches with high adult hellbender densities. Our results suggest that artificial shelters are effective tools for studying hellbenders when designed optimally, maintained frequently enough, and placed in appropriate locations. However, exceptions to these findings may exist in certain heavily degraded stream reaches.

No description available.

Cryptobranchus guildayi is described as an extinct species of large salamander that is closely related to the hellbender, Cryptobranchus alleganiensis. The validity of this extinct taxon has been questioned, so an expanded osteological sample of modern hellbenders was used for comparative purposes with the C. guildayi fossil material. Based on this analysis, all supposed distinguishing morphological characteristics used to define C. guildayi can be observed in specimens of C. alleganiensis, or are based on misidentifications. Therefore, Cryptobranchus guildayi is considered to be conspecific with C. alleganiensis and taxonomically should be considered a junior synonym of the latter. The reassignment of the C. guildayi specimens to C. alleganiensis and examination of undescribed fossil specimens from the same region expands the prehistoric range of the species to the Potomac River and its tributaries and also extends the age of the species to the Irvingtonian North American land mammal age.

The behavior of humans and animals is an important component of conservation. The way people behave can cause environmental harm, but it also can be a solution to conservation challenges. Similarly, wildlife can respond to changing environments in ways that are detrimental to their survival, but they can also in some cases adapt or even thrive in human-impacted environments. In this dissertation, I discuss the ways in which human and hellbender behaviors relate to conservation. First, using survey and interview data, I explore the reasons why private landowners allow access to their property for research. I find that landowners are more likely to allow research on their property if they have previously allowed research, if they are interested in learning about the research taking place, if they have larger properties, and if they had positive attitudes towards conservation. Conversely, they are less likely to allow access to their property if they are concerned that doing so might restrict free use of their property. Other possible predictors that I investigate, such as landowner demographics, landowner trust in science, and landowner attitudes towards hellbenders are not significant predictors of allowing research. I next explore the effects of engaging landowners in research either via citizen science or "traditional" private lands research where scientists work on the landowner's property, but the landowner is not involved in data collection. I assess the effects of these types of engagement on landowner conservation knowledge, attitudes, awareness, and behavioral intentions and compare the effects across these two treatment groups and a control. I find similar changes in both the traditional and citizen science treatment groups, with involvement in the research leading to greater conservation knowledge, increased awareness of conservation concerns, more positive attitudes towards conservation, and/or more conservation behavioral intentions. However, I observe limited behavior change in any treatment group, and I identify a lack of efficacy and a hesitancy to accept responsibility for water quality degradation as possible barriers to behavior change. My investigations of animal behavior utilize custom-built underwater infrared camera technology to study hellbender reproductive behavior. I first add to current understanding of hellbender breeding behavior by describing the basic hellbender mating sequence, identifying the presence of potential alternative mating tactics, and describing two novel behaviors, including possible signal production via wave-based communication and a unique egg laying behavior by female hellbenders. I then measure the extent to which hellbender males (which provide the parental care) may help protect their offspring from low oxygen and high siltation, and I assess the possibility of trade-offs between parental care behaviors that benefit the eggs and self-maintenance behaviors that benefit the parent. I find that guarding male hellbenders increase both their parental care behaviors and their self-maintenance behaviors in response to low dissolved oxygen, but that they also show evidence of a trade-off between the two, with males ceasing parental care in favor of self-maintenance at sufficiently low levels of dissolved oxygen. Males show no parental response to high levels of silt. My findings add to our understanding of human and animal behavior and highlight the importance of behavioral flexibility to conservation. I find that hellbenders can to some extent modify their behaviors to compensate for the impacts of poor stream management on their own and their offspring's health, and I find that engaging landowners in research can encourage changes in awareness, attitudes, and behavioral intentions regarding conservation. / Doctor of Philosophy / The behavior of humans and animals is an important component of conservation. The way people behave can cause environmental harm, but it also can be a solution to conservation challenges. Similarly, wildlife can respond to changing environments in ways that are detrimental to their survival, but they can also in some cases change to survive or even thrive in human-impacted environments. In this dissertation, I discuss the ways in which human and hellbender behaviors relate to conservation. First, using survey and interview data, I explore the reasons why private landowners allow access to their property for research. I find that landowners are more likely to allow research on their property if they have previously allowed research, if they are interested in learning about the research taking place, if they have larger properties, and if they had positive attitudes towards conservation. Conversely, they are less likely to allow access to their property if they are concerned that doing so might restrict free use of their property. Other possible predictors that I investigate, such as landowner age and sex, landowner trust in science, and landowner attitudes towards hellbenders are not significant predictors of allowing research. I next explore the effects of engaging landowners in research either via citizen science, where landowners help collect data, or "traditional" private lands research where scientists work on the landowner's property, but the landowner is not involved in data collection. I assess the effects of these types of engagement on landowner conservation knowledge, attitudes, awareness, and planned actions and compare the effects across these two treatment groups and a control. I find similar changes in both the traditional and citizen science treatment groups, with involvement in the research leading to greater conservation knowledge, increased awareness of conservation concerns, more positive attitudes towards conservation, and/or more conservation planned actions. However, I observe limited behavior change in any treatment group, and I identify a lack of perceived ability to make a difference among landowners and a hesitancy to accept responsibility for water quality decline as possible barriers to behavior change. My investigations of animal behavior use custom-built underwater night-vision cameras to study hellbender baby-making. I first add to current understanding of hellbender breeding behavior by describing basic hellbender mating activities, identifying the possibility that some males sneak into other male's nests to mate, and describing two new behaviors, including possible signal production via sound or vibration and a unique egg laying behavior by female hellbenders. I then measure how much hellbender males (which provide the parental care) may help protect their eggs from low oxygen and high dissolved dirt, and I assess the possibility of trade-offs between parental care behaviors that benefit the eggs and self-maintenance behaviors that benefit the parent. I find that guarding male hellbenders increase both their parental care behaviors and their self-maintenance behaviors in response to low dissolved oxygen, but that they also show evidence of a trade-off between the two, with males stopping parental care in favor of self-maintenance at low levels of dissolved oxygen. Males show no parental response to high levels of dissolved dirt. My findings add to our understanding of human and animal behavior and highlight the importance of behavioral flexibility to conservation. I find that hellbenders can to some extent change their behaviors to compensate for the impacts of poor stream management on their own and their children's health, and I find that engaging landowners in research can encourage changes in awareness, attitudes, and planned behaviors regarding conservation.

<p>  </p> <p>The Eastern Hellbender (<em>Cryptobranchus alleganiensis alleganiensis</em>) is a fully aquatic salamander found throughout the eastern United States. Hellbenders require cool, fast-moving rivers and streams with flat rock substrates for shelter. Due to habitat degradation and anthropogenic changes across landscapes, Hellbenders have required intervention programs to reduce extirpation and extinction risks. Over 5000 Hellbenders are found in captive-rearing and breeding programs throughout 15 different states. However, captive-rearing standards vary from facility to facility. </p> <p>Currently, Hellbender captive-rearing programs are based on established zoo guidelines that recommend rearing in traditional glass aquaria until they reach releasable mass (~60 g) at approximately three years of age. To achieve releasable size, the guidelines provide density and food availability requirements based on the amount of available floor space of the enclosure. Unfortunately, because these guidelines lack empirical data, it is unclear whether these recommendations are optimizing captive-rearing efforts for Hellbenders and, therefore, optimizing conservation potential. </p> <p>There is an overall lack of available information on housing conditions and requirements for Hellbenders outside of intraspecies aggression or cannibalism. Because many facilities use different types of housing conditions, there is substantial variation in the time needed to achieve the release size threshold. Our objectives were to: 1) understand how different raceway sizes impact growth rates of juvenile Hellbenders and 2) understand the effects of density and food availability on larval Hellbender growth. Both of these goals will allow us to develop optimal housing and husbandry standards and optimizing conservation potential within rearing facilities. Our study will build on our current knowledge of Hellbender captive-rearing techniques and provide empirical data to create optimal rearing standards nationwide. </p>