Validating an automated classification system for snake movement behavior: refining and extending the radio telemetry-accelerometry framework

An animal’s behavioral decisions, such as when, why, and how individuals move through their environment, are mediated by a complex interplay between internal (e.g., sex, physiological state, motivational state) and external (e.g., environmental conditions, predation, competition) factors. A detailed understanding of the causes and consequences of these decisions for many species has historically been precluded by methodological constraints. However, a recent wave of advancements in sensor technologies circumvents many of these traditional limitations and has spurred the emerging field of biologging science. Animal-attached dataloggers (or biologgers) give researchers the ability to remotely monitor an individual’s physiology and behavior in the field at resolutions and precisions historically restricted to laboratories. Accelerometer dataloggers, specifically, are small (\u3c 1 g) piezo-electric (springlike) sensors that measure three-dimensional acceleration (upward, downward, and side-to-side) derived from subject motion, enabling interpretation of a wide range of movement-mediated behaviors. This project aims to expand on a recently developed framework for accelerometer monitoring in snakes, a group that has otherwise been completely overlooked in biologging applications. The proposed validation procedures are the essential first step toward translating these techniques to field applications, and, ultimately, improving analysis of the relationships between snake behavior and key internal and environmental variables

Revisiting the energetics hypothesis: can accelerometer monitoring reveal hidden variation in the movement patterns of snakes?

Historically, predators have been classified into two categories based upon how they search for and acquire prey. Active foragers move through the environment in search of prey, while ambush foragers “sit-and-wait” in selected positions for prey to pass. This difference in energetic demands is expected to correlate with disparities in the time species allocate to various behaviors. According to this energetics hypothesis, ambush foragers should exhibit reduced movement and space use relative to co-occurring active foragers. Snakes represent traditionally overlooked model organisms for exploring these associations, particularly the interplay between movement, foraging mode, and thermal preferences. Radio telemetry is the primary tool for measuring snake movement, however, coarse measures of activity hinder examination of movement patterns at finer temporal scales. This study capitalizes on recently validated procedures integrating radio telemetry and accelerometry for continuous monitoring of the spatial and temporal dimensions of movement behavior in snakes. We will carry out an improved test of the energetics hypothesis by exploring these associations in ambush-foraging Timber Rattlesnakes (Crotalus horridus) and active-foraging Rat Snakes (Pantherophis alleghaniensis). This project will provide a blue-print for future hypothesis-driven studies on movement behavior in small and secretive species using emerging animal-borne datalogging technologies

The Effects of Roadways on the Spatial and Temporal Movement Patterns of Timber Rattlesnakes (Crotalus horridus)

Roadways are among the most widespread and disruptive anthropogenic land use features that influence the behavior and movement of wildlife. Negative impacts include vehicle-induced mortality, habitat destruction and fragmentation, and creating barriers to movement which can have far-reaching sub-lethal effects. In an effort to improve upon historical methods of evaluating the influence of prominent landscape features, such as roads, on the movement of small and secretive wildlife, we are using a novel integration of emerging spatial analyses and tri-axial accelerometry in Timber Rattlesnakes (Crotalus horridus) from central Georgia. We used dynamic Brownian Bridge Movement Models to estimate motion variance and utilization distributions (UDs) for individual rattlesnakes, and accelerometers simultaneously provide long-term and continuous activity budgets to quantify “real-time” temporal movement patterns. Relating these spatial and temporal metrics to the Mean Distance to Roadway (MDR) revealed no significant associations when considering the full sample. However, sub-setting the data by sex revealed a significant positive linear relationship in males between MDR and Distance Per Movement (DPM) and UDs. These preliminary results indicate that with decreasing distance to roads, males use less space and move shorter distances per movement (DPM), suggesting that roads might pose as a passive barrier to movement for males in our population. Interestingly, we also detected a significant negative linear relationship between MDR and mean Hours spent Moving per Day (HMD) by male rattlesnakes. Given that this opposing relationship between MDR and the spatial and temporal patterns of movement was not displayed by females, we suspect that males in close proximity to roads might be compensating for smaller home range sizes (and reduced overlap with females) by increasing activity (HMD) during the mating season (August-October) to elevate encounter frequencies with reproductive females. Increasing our sample size and duration of monitoring will help to refine these preliminary findings

High-frequency accelerometer recording of key predatory behaviors in vipers: validation and case study with Timber Rattlesnakes (Crotalus horridus)

High-frequency accelerometer recording of key predatory behaviors in vipers: validation and case study with Timber Rattlesnakes (Crotalus horridus) Morgan Thompson, Richard H. Adams, Anna F. Tipton, and Dominic L. DeSantis Tri-axial accelerometers (ACTs) are becoming increasingly common in studies of animal behavior wherein direct observation of subjects in nature is constrained or impossible. ACTs are small (\u3c 1 g) piezo-electric (spring-like) sensors that measure three-dimensional acceleration (upward, downward, and side-to-side) derived from subject motion. When leveraged with advanced machine learning techniques, these data can enable precise automated classification of a wide range of movement-mediated behaviors. Until recently, ACTs were largely reserved for larger-bodied organisms or those most amenable to the temporary external attachment of devices. Ongoing ACT miniaturization has now expanded the breadth of organisms amenable to these methods. This project aims to expand on a recently developed framework for ACT monitoring in wild-ranging snakes, a group that has been mostly overlooked in biologging applications. We are currently conducting extensive captive validation trials for robust model training and testing to enable classification of predatory behaviors, including striking and ingestion of prey items, in Timber Rattlesnakes (Crotalus horridus). Following captive validation, we will translate this method to the field with a population of C. horridus in the lower Piedmont of middle Georgia to evaluate the efficacy of externally attached ACTs for remote and continuous monitoring of predatory behaviors by wild-ranging vipers. We envision validation of this technique carrying significant conservation and management implications; real-time monitoring of foraging efficiency in the field opens the door to improved interpretation of the causes and consequences of variation in individual behavior and performance, and its ultimate effects on population trajectories

Conserving the Mesoamerican herpetofauna: The most critical case of the priority level one endemic species

Of significant biodiversity importance, the Mesoamerican herpetofauna now increases at a rate of approximately 35 species annually. As its size increases, however, the global problem of biodiversity decline continues to worsen with time. Recently, a set of conservation priority levels was established for individual species based on a combination of physiographic distribution and Environmental Vulnerability Score (EVS). The 18 such levels identified range from level one, encompassing species that occupy a single physiographic region and with a high EVS, to level 18, including species that inhabit six physiographic regions and have a low EVS. For the Mesoamerican herpetofauna, the greatest number of species is placed in level one, amounting to 970 taxa with documentable distributions. From one to 149 priority level one species are found in 20 of the 21 physiographic regions recognized in Mesoamerica. Slightly more than three-quarters of the priority level one species of anurans, salamanders, and squamates are found in the Baja California Peninsula and six montane regions in Mexico and Central America. Conservation biology, thus far, has not been successful at reversing the steady loss of biodiversity nor at placing biodiversity decline on the global agenda. In addition, humans are becoming increasingly divorced from contact with the natural world and, thus, less aware of the life-threatening impact they are having on the planet’s life-support systems. Given this situation, the authors of this paper have become increasingly devoted to trying to understand why humans in general exhibit the highly dangerous anthropocentric worldview. As have other biologists, the authors ascribe this behavior to what is known as “the mismanagement of the human mind.” This mismanagement of the human mind is believed to result from a cascade of psychological ailments giving rise to increasingly restrictive forms of centristic thinking. In the final analysis, these types of thinking appear likely to doom to failure any efforts to establish for perpetuity protected areas that can harbor the priority level one species identified in this and earlier papers. Until and unless the anthropocentric worldview can be transformed into a worldview consonant with the realities of how life operates on planet Earth, we humans are not only endangering ourselves but also all other life. This article discusses the implications of this worldview for the potential conservation of the priority level one endemic species of the Mesoamerica herpetofauna

Biological and cultural diversity in the state of Oaxaca, México: Strategies for conservation among indigenous communities

Oaxaca es el estado de México con mayor diversidad biológica y cultural. Los pueblos originarios de Oaxaca son todos descendientes, total o parcialmente, de la antigua cultura madre Olmeca también conocida como “Pueblo del Jaguar”. Estos pueblos originarios actualmente están tratando de defender sus territorios y bienes naturales comunes de la explotación por parte de los gobiernos y las grandes empresas multinacionales. Oaxaca es el quinto estado más grande de México y comprende 12 regiones fisiográficas y 16 grupos etnolingüísticos originarios. La alta diversidad cultural que se observa en Oaxaca está interrelacionada con la considerable diversidad biológica y ambiental y debe entenderse que la protección de una depende de la protección de la otra. El conocimiento de la biodiversidad de Oaxaca continúa aumentando, especialmente entre los vertebrados tetrápodos. La diversidad cultural en Oaxaca, especialmente con respecto a los idiomas, es la más diversa en todo México. En varias comunidades, ejidos y con pequeños propietarios existe un sistema de Áreas Comunitarias de Conservación, que permiten la protección de diversas especies no incluidas dentro de las ANPs federales, así como cuerpos de agua y los bosques dentro del estado. Estas ACC son parte de un movimiento de resistencia contra la participación en el sistema formal de ANP por decreto. Los pueblos indígenas de Oaxaca son parte de una comunidad global de personas que se sabe que son responsables de la protección de alrededor del 80% de la biodiversidad remanente del mundo. Los propios esfuerzos del gobierno mexicano por la conservación se remontan a la administración del presidente Lázaro Cárdenas de Río. Los intentos de manejo forestal comunitario de los pueblos indígenas de todo el mundo han sido apoyados o no por los gobiernos federales. Los pueblos indígenas de la Sierra Madre de Oaxaca están utilizando el ecoturismo de bajo impacto como un medio adicional para conservar sus tierras y para apoyar estilos de vida sostenibles, al tiempo que se resisten a los esfuerzos de explotación de los grupos no indígenas de la sociedad. El Corredor Interoceánico constituye la amenaza más significativa para los esfuerzos de estos grupos indígenas, así como otras actividades comerciales a gran escala realizadas por grandes consorcios industriales suscritos por sus aliados políticos en el gobierno federal, cuestionando por qué las ANPs que existen realmente a qué personas se suponen un beneficio. A la luz de esta realidad, hemos realizado una serie de recomendaciones para el alivio de estos problemas a los pueblos originarios que permitan continuar con sus esfuerzos de preservación de la biodiversidad nativa y su propia diversidad cultura

The herpetofauna of Veracruz, Mexico: composition, distribution, and conservation status

The herpetofauna of the state of Veracruz, Mexico, currently consists of 359 species, including 76 anurans, 45 caudates, one caecilian, one crocodylian, 217 squamates, and 19 turtles. The distribution of the herpetofaunal species are catalogued here among the four recognized physiographic regions in the state. The total number of species ranges from 179 in the Sierra de Los Tuxtlas to 236 in the Sierra Madre Oriental. The number of species shared among the four physiographic regions ranges from 100 between the Gulf Coastal Lowlands and the Transmexican Volcanic Belt, to 190 between the Sierra Madre Oriental and the Transmexican Volcanic Belt. A similarity dendrogram based on the Unweighted Pair Group Method with Arithmetic Averages (UPGMA) depicts two distinct clusters, one between the Sierra Madre Oriental and the Transmexican Volcanic Belt, and the other between the Gulf Coastal Lowlands and the Sierra de Los Tuxtlas. The former cluster refects two adjacent regions in highland environments that share a substantial number of herpetofaunal species, and the latter cluster shares a sizeable number of wide-ranging, generalist, lowland species found on the Atlantic and Pacifc versants of Mexico and Central America. The level of herpetofaunal endemism is relatively high, with 182 of 359 species either endemic to Mexico or to Veracruz. The distributional categorization of the total herpetofauna is as follows: 169 non-endemic species; 138 country endemic species; 44 state endemic species; and eight non-native species. The 169 non-endemic species are allocated to the following distributional categories: MXCA (89), MXSA (30), MXUS (29), USCA (11), USSA (four), and OCEA (fve). The principal environmental threats to the herpetofauna of Veracruz include deforestation, livestock, roads, water pollution, myths and other cultural factors, diseases, invasive species, and illegal commerce. The conservation status of each native species was evaluated using the SEMARNAT, IUCN, and EVS systems, of which the EVS system proved to be the most useful. The Relative Herpetofaunal Priority method was employed to determine the rank order signifcance of the four regions, and this identifed the Sierra Madre Oriental as the region of greatest importance. Only six protected areas exist in Veracruz, most of which are located in the Gulf Coastal Lowlands, the region of least conservation signifcance. The area of greatest signifcance, the Sierra Madre Oriental, does not contain any protected areas. A total of 265 species have been recorded within the six protected areas, of which 138 are non-endemics, 89 are country endemics, 31 are state endemics, and seven are non-natives. Finally, we provide a set of conclusions and recommendations to enhance the prospects for the future protection of the herpetofauna of Veracruz

Mesoamerican salamanders (Amphibia:Caudata) as a conservation focal group

Las salamandras constituyen el segundo orden más grande de anfibios en el mundo. Las 762 especies que ocurren a nivel mundial están organizadas en nueve familias, de las cuales ocho se encuentran en el hemisferio occidental. Las 308 especies de salamandras mesoamericanas están distribuidas en cuatro familias, solo dos de las cuales tienen representantes que se encuentran significativamente al sur de la frontera de México y Estados Unidos. Esas dos familias son Ambystomatidae, con 18 especies mesoamericanas, y Plethodontidae, con 287 especies. La mayoría de las salamandras mesoamericanas son endémicas de México o Centroamérica o de Mesoamérica en general. La mayor cantidad de especies endémicas pertenece a los géneros Ambystoma, Bolitoglossa, Chiropterotriton, Nototriton, Oedipina, Pseudoeurycea y Thorius. La mayor diversidad de salamandras se encuentra en México, seguido en orden por Guatemala, Costa Rica, Honduras, Panamá, Nicaragua, El Salvador y Belice. La cantidad de endemismo varía en orden de mayor a menor en Costa Rica, Nicaragua, Guatemala, Honduras, Panamá, El Salvador y Belice. La mayoría de las especies de salamandras mesoamericanas ocupan el nivel de prioridad de conservación uno, con un total de 244 especies y el 88.4% de las 276 especies endémicas de México y Centroamérica. Estas 244 especies constituyen un grupo de enfoque de conservación clave para Mesoamérica basado en varios criterios. La mayoría de las especies del nivel de prioridad de conservación uno, están ubicadas en la Mesa Central, la Sierra Madre Occidental, la Sierra Madre Oriental, la Sierra Madre del Sur, la Sierra de Los Tuxtlas, las tierras altas de Centroamérica nuclear occidental y oriental, las tierras altas del Istmo de Centroamérica y las tierras altas del este de Panamá. En términos generales, la importancia del recurso de biodiversidad representado por las salamandras mesoamericanas no es tomado en cuenta fuera de un pequeño grupo de herpetólogos y taxónomos interesados en la conservación del grupo en la región. No obstante, estas salamandras están actualmente amenazadas por las actividades destructivas de los humanos y potencialmente amenazadas por la posibilidad de la invasión de sus hábitats por el hongo quítrido Batrachochytrium salamandrivorans. Nuestra conclusión es que las salamandras mesoamericanas deberían ser promovidas como un grupo de enfoque de conservación por varias razones. Adicionalmente, sugerimos que estas salamandras se conviertan en el tema de un congreso científico que aborde la preparación de un plan para la protección de la diversidad y endemismo de estos anfibios para la perpetuidad lo más pronto posibl

Movement Ecology Of A Cryptic Ambush Predator: Integrating Radio Telemetry And Tri-Axial Accelerometry To Evaluate Spatial Strategies And Activity Patterns By Western Diamond-Backed Rattlesnakes (Crotalus atrox)

An animal\u27s decision to move from one location to another within its environment is determined by a complex blend of internal and external factors. Teasing apart the relative roles of specific variables in this web of interacting mechanisms has been a long-standing challenge in animal movement ecology. Historically, this problem was viewed as a sort of black box for which a myriad of methodological limitations precluded rigorous study. Recently, a diversity of animal-borne transmitters and dataloggers (i.e., bio-loggers) have circumvented many of these traditional limitations and transformed field studies of animal movement, behavior, and physiology - in some cases, allowing for testing of entirely new theories. Among these technologies, tri-axial accelerometers (ACTs), which enable remote and continuous recording of animal activity, are becoming increasingly commonplace in longitudinal field studies. One of the many strengths offered by ACTs is the ability to be paired with other sensors to provide multiple, complementary data types. In the recent explosion of such integrative bio-logging applications, a distinct taxonomic bias is evident, with smaller-bodied terrestrial taxa often being overlooked because of greater difficulty in device attachment or implantation. Significant computational challenges also remain with these big data that are often exacerbated in pilot studies with novel study species. Herein, an integrative framework coupling radio telemetry and accelerometry (RT-ACT) is developed and validated through a case study on Western Diamond-backed Rattlesnakes (Crotalus atrox), representing the first example of snakes as a focal organism in bio-logging research. Telemetry proved to be critical in ACT validation procedures, enabling periodic field observations of rattlesnake behavior that were used to train and test supervised machine learning models for behavioral classification. Following model training, Random Forest and Generalized Linear-NET algorithms distinguished between periods of activity and inactivity at very high accuracies (99.0% and 97.0%, receptively), allowing automated classification of activity in extensive ACT field datasets (94 ï?± 99 days, range = 6ï?­289 days). These classifications enabled the construction of continuous activity budgets for evaluation of the timing and duration of activity at multiple temporal scales. In general, activity patterns were found to be highly variable within and between individuals, as the proportion of time spent active per individual dataset ranged from 1.6% to 37.1%. The same general daily activity pattern was conserved across all active seasons (spring, summer, fall), with the majority of activity occurring during the evening or nocturnal diel periods. There was seasonal variation in activity duration within diel periods, as activity increased during the summer-mating season, possibly reflective of characteristic mate-searching efforts by male rattlesnakes. Moving forward, long-term and low-frequency ACT field-monitoring could play an important role in improving our understanding of organismal responses to shifting environmental conditions, particularly in small, secretive terrestrial taxa for which other bio-logging technologies are not applicable. Independent captive observations might also allow classification of additional cryptic behaviors (even at very low ACT recording frequencies (1-Hz)) not often observed in the field, ultimately enabling real-time tracking of individual behavior and performance that can be linked to population dynamics. In addition to its role in validating the RT-ACT framework, radio telemetry was also used to explore the effects of sex, behavioral season, and critical resource distribution on the spatial strategies of C. atrox. Specifically, seasonal movement and space use patterns were used to test whether Native Habitats (NH) and human-made Resource Hotspots (RH) on the Indio Mountains Research Station facilitate divergent search strategies in response to critical resources, including potential mating partners, being widely dispersed in NH and clustered in RH. Independent of habitat category, seasonal patterns largely reflected those expected in a male-search based mating system. However, accounting for individuals using primarily NH and those using RH revealed divergent strategies. NH males used more space than RH males within both behavioral seasons, and NH males increased movement distances and space use during the mating season while RH males displayed no significant seasonal shifts. NH females elevated movement distances during the mating season while RH displayed no seasonal shifts in movement or space use. Collectively, seasonal spatial patterns and observations of reproductive behavior uncovered contrasting patterns by NH and RH individuals that might represent alternative optimal strategies in this unique system, highlighting the potential for multiple interacting mechanisms (sexual selection, behavioral plasticity, and habitat heterogeneity) to drive disparate tactics within populations. In summary, this dissertation illustrates: 1) the transformative potential of integrative bio-logging approaches in field studies of movement behavior through the development and validation of the novel RT-ACT framework, and 2) the retained value of traditional data collection techniques (i.e., radio telemetry) in specific contexts

BEHAVIORAL CORRELATES OF OVERWINTERING SITE SELECTION IN A SOUTHEASTERN POPULATION OF TIMBER RATTLESNAKES (CROTALUS HORRIDUS)**

Studies of temperate snake behavioral ecology are historically focused on the active season. However, behavior during the winter inactive period also carries significant fitness consequences, as populations are under strong selective pressure to select optimal shelter sites that minimize the costs of low temperatures and prolonged inactivity. This importance of overwintering site selection is well illustrated by the widespread documentation of large communal dens in northern species and populations. However, comparatively little systematic research exists for overwintering behavior at more southern temperate latitudes, despite winter in these regions presenting snakes with the same selective pressures, albeit moderated in intensity. Temperate species that occur across wide latitudinal gradients can therefore serve as ideal models for exploring variability in winter behavior and ecology across different selection regimes. Timber Rattlesnakes (Crotalus horridus) are one such example, as the majority of inactive season research is conducted on northern and montane populations for which communal denning is common. We aim to capitalize on a unique southeastern population of C. horridus from the lower Piedmont of Georgia, USA, wherein solitary and communal overwintering site use are observed at comparable frequencies. We will use a novel combination of remote videography, radio telemetry, and accelerometry to evaluate associations between winter shelter type and rattlesnake behavior from two perspectives: 1) migratory distance (radio telemetry) to overwintering site and 2) basking frequency (remote videography) and activity level (accelerometry) during the overwintering periods (November-April) in 2022 and 2023. Our aim is to explore the relative behavioral trade-offs associated with communal and solitary overwintering strategies in this population, and when combined with ongoing monitoring of body mass loss and Opidiomyces ophidiicola (“Snake Fungal Disease”) infection prevalence in this system, we intend to provide a comprehensive framework for evaluating the causes and consequences of variability in overwintering site selection in temperate snake populations