Master of Science, The Ohio State University, 2023, Environment and Natural Resources

The federally threatened eastern massasauga rattlesnake (Sistrurus catenatus) occurs across the Great Lakes region of the midwestern United States in increasingly small and fragmented populations. While massasaugas are relatively well-studied among snakes, much is still unknown about their baseline habitat requirements, as well as how they move across heterogeneous landscapes. One of the most stable remaining populations outside the species strongholds of Michigan and Ontario is found at a wildlife area in northern Ohio. My research objectives were to: 1) identify land use practices and habitat features that best predict massasauga occurrence at the wildlife area; and 2) determine how the wildlife area is functionally connected for massasaugas given the amount of active agricultural production still taking place on the landscape and the species' tendency not to travel great distances. During the 2022 field season, I used adapted-Hunt drift fence technique (AHDriFT) camera arrays and timed constrained visual encounter surveys to assess massasauga occupancy and created single-species integrated occupancy models to establish which covariates best predicted occupancy. Massasaugas were more likely to occupy sites with a higher proportion of open herbaceous habitat, sites with a higher proportion of marginal habitat features like infrequently mowed ditches and field margins, and sites that had been out of agricultural production for a longer time. I created a series of cumulative kernel density surfaces using three different dispersal kernels to analyze functional connectivity for massasaugas at the wildlife area. I also examined the potential impact of agriculture on connectivity by using three alternative resistance values for agriculture in the resistance surface. The probability of detecting dispersing massasaugas was highest in and around the heavily occupied center of the wildlife area. Using the mean rank for each of the 45 agricultural fields across the nine (open full item for complete abstract)

Committee: William Peterman (Advisor); Christopher Tonra (Committee Member); Stephen Matthews (Committee Member); Gabriel Karns (Committee Member) Subjects: Conservation; Ecology; Wildlife Conservation; Wildlife Management

Doctor of Philosophy, The Ohio State University, 2022, Evolution, Ecology and Organismal Biology

Successful conservation actions require a detailed understanding of how individuals interact with their environment. For many threatened and endangered species, anthropogenic changes to their landscape have created barriers separating formerly connected populations. This isolation can have profound impacts on the long-term viability of these populations and ultimately the conservation status of the species. For example, as populations become more isolated, they may enter the “extinction vortex” where small populations experience high levels of inbreeding and genetic drift depressing demographic rates, driving the population into a positive feedback loop that can lead to a decline in numbers and eventual extinction. However, if barriers to movement are not complete, even infrequent dispersal between populations can counter potential vortex effects by bolstering local population sizes and introducing new genetic material. Determining if populations are connected via dispersal or if they are isolated is a difficult question with no single best approach. For the Federally threatened Eastern Massasauga Rattlesnakes, Sistrurus catenatus, their reclusive, sedentary lifestyle make many field-based methods for generating this information difficult and unreliable without unrealistic investments of time and resources. In my thesis, I used information from DNA single nucleotide polymorphisms (SNPs) from neutral genetic markers to address the following three fundamental questions regarding how S. catenatus move through their landscape in Ohio and how this information can be used to evaluate proposed activities for their conservation: (1) Do snakes in scattered habitat patches across Northeastern Ohio belong to a single connected population, a metapopulation with infrequent dispersal, or isolated populations? I used 1000s of DNA SNPs to reconstruct a pedigree across 86 individuals and showed that no individuals have moved between habitat patches separated by more than a few (open full item for complete abstract)

Committee: H. Lisle Gibbs (Advisor); Andreas Chavez (Committee Member); Bill Peterman (Committee Member) Subjects: Conservation; Ecology; Wildlife Conservation

Master of Science, The Ohio State University, 2021, Environment and Natural Resources

The Eastern Massasauga Rattlesnake (Sistrurus catenatus) is Federally threatened and Ohio endangered. Accepted Ohio survey protocols includes visual encounter surveys (VES) and artificial cover (corrugated tin sheets) surveys. Although effective, these traditional methods require intensive field effort (~25 weekly visits). The Adapted-Hunt Drift Fence Technique (AHDriFT) is a new low-effort camera trap and drift method for ectotherms and small mammals. However, the method has not been applied for Massasauga or in their habitats, or even evaluated beyond proof-of-concept. The objectives of this study were to: (1) assess AHDriFT as a wildlife survey tool; (2) compare AHDriFT efficacy for Massasauga presence-absence surveys to VES and tin surveys in terms of detection rates, detection probability, and cost-efficiency; (3) determine optimal AHDriFT deployment for Massasauga in terms of camera trap timing and length, array spatial placement, and weather influence; and (4) provide preliminary recommendations for a Massasauga survey protocol using AHDriFT. I deployed 15 Y-shaped AHDriFT arrays in fields with known Massasauga populations from March – October 2019 and 2020. In 2019, I compared arrays to prior VES and tin surveys, and assessed between-field detection covariates. In 2020, I evaluated concurrent surveys and assessed within-field detection covariates. Equipment for each array cost approximately US$1,570. Construction and deployment of each array took about three hours, with field servicing requiring 15 minutes per array. Arrays proved durable under wind, ice, snow, flooding, and heat. Processing two-weeks of images of 45 cameras averaged 13 person-hours. In 2019, arrays obtained 9,018 detections of 41 vertebrate species comprised of 5 amphibians, 13 reptiles (11 snakes), 16 mammals, and 7 birds. Arrays cumulatively detected all amphibians and 92% of expected snakes and small mammals. Arrays obtained a total of 206 Massasauga detections, 2 – 4 times that of (open full item for complete abstract)

Committee: William Peterman Dr. (Advisor); Stanley Gehrt Dr. (Committee Member); Christopher Tonra Dr. (Committee Member) Subjects: Environmental Science; Natural Resource Management; Wildlife Conservation; Wildlife Management

Doctor of Philosophy, The Ohio State University, 2016, Evolution, Ecology and Organismal Biology

The Eastern Massasauga Rattlesnake (Sistrurus catenatus catenatus) is a rare species across its range and is thought to be experiencing widespread population declines. Application of conservation-oriented management practices to this species is hindered by incomplete knowledge of the spatial distribution of populations and suitable habitat. To address this obstacle to conservation efforts I developed species distribution models (SDMs) for northeastern Ohio and Michigan and incorporated the resulting habitat suitability maps (HSMs) in a range of landscape ecology applications. These models were generated using the software program Maxent and a series of environmental variables that represent different elements of Eastern Massasauga habitat association, including vegetation attributes (Landsat derived vegetation indices; LiDAR) and relative elevation (topographic position index). The Maxent model with the best predictive capacity to identify extant northeastern Ohio populations used location data from across the state. The model selected LiDAR data as the top contributing variable. Northeastern Ohio is a priority for Eastern Massasauga conservation in the state so I also conducted an analysis of historical land use and land cover change to better understand the distribution of populations and habitat in this region. I used object-based classification techniques to analyze historical aerial photographs (covering ~75 years) and found that present day populations and suitable habitat largely coincided with abandoned agricultural fields. In the absence of natural disturbance agents, agricultural fields that were allowed to go fallow represented an important source of early successional habitats that are vital to Massasauga. The early successional, open canopy habitats that Eastern Massasauga rely on are not permanent fixtures in this landscape making habitat management a necessity. The Michigan SDM was on a much broader scale than the Ohio modeling effort incorporating 60 (open full item for complete abstract)

Committee: Thomas Hetherington (Advisor) Subjects: Ecology; Wildlife Conservation

Doctor of Philosophy, The Ohio State University, 2011, Evolution, Ecology and Organismal Biology

Many evolutionary and ecological factors can have strong and significant effects in small isolated populations when compared to larger, more connected populations. For example, isolated populations of endangered species are often at greater risk for extinction because of the potential loss of genetic diversity and the negative effects of inbreeding and inbreeding depression. Reduced levels of gene flow among isolated populations may also lead to differentiation in important ecological factors such as diet. The eastern massasauga (Sistrurus c. catenatus) is an endangered snake that is found in isolated populations throughout eastern North America. In this dissertation, I address both genetic and ecological consequences of these snakes existing in small isolated populations. In Chapter 2, I used data from 19 microsatellite loci to assess levels of genetic variation and to compare rates of historical and contemporary gene flow among populations of the these snakes. Overall, massasauga populations display high levels of genetic differentiation and differ by an order of magnitude in genetic effective population size. Historical and contemporary migration rates are low and similar in magnitude. There is little evidence that populations have experienced a sharp decline in population size and a comparative modeling approach favors a model of long-term drift-migration equilibrium. In Chapter 3, levels of inbreeding were accessed in these populations and I tested for the presence of a heterozygosity-fitness correlation between individual multilocus heterozygosity (MLH) and an estimate of fitness, body condition This analysis revealed significant variation in mean MLH and mean body condition among populations but no correlation between them. This result was true even after controlling for non-genetic factors such as sex, season of capture and year of capture. Tests for inbreeding were also negative and suggest snakes are mating randomly within each population. Finally, in Ch (open full item for complete abstract)

Committee: H. Lisle Gibbs PhD (Advisor); Peter Curtis PhD (Committee Member); Paul Fuerst PhD (Committee Member) Subjects: Biology; Ecology; Genetics; Molecular Biology