Modeling Habitat Suitability and Population Demographics of the Eastern Massasauga Rattlesnake in Managed Lands in Southwestern Michigan PDF Download
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Author: Robyn Leah Bailey
Publisher:
ISBN:
Category : Eastern massasauga
Languages : en
Pages : 280
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Author: Robyn Leah Bailey
Publisher:
ISBN:
Category : Eastern massasauga
Languages : en
Pages : 280
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Author: Kristin Marie Bissell
Publisher:
ISBN:
Category : Eastern massasauga
Languages : en
Pages : 284
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Author: Eric T. Hileman
Publisher:
ISBN: 9781369538120
Category : Eastern massasauga
Languages : en
Pages : 147
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The Eastern Massasauga (Sistrurus catenatus) is a small, cryptic North American rattlesnake with a distribution centered on the Great Lakes. It is listed as threatened and endangered in Canada. In the United States, ongoing population declines due to habitat loss, habitat fragmentation, and harvest led to the species being listed as threatened under the U.S. Endangered Species Act in 2016. Estimates of population parameters are essential for modeling population dynamics, assessing population viability, and elucidating the effects of land management practices on population persistence. However, conservation of Eastern Massasauga populations has been hampered by information gaps related to life history and hibernation phenology. In addition, key demographic parameter estimates are lacking for populations near the range center of the species where the largest number of Eastern Massasauga populations may still persist. Consequently, biologically realistic population viability analyses and management guidelines related to the timing of habitat management activities have been difficult to develop. In this study, I address these data gaps by providing 1) a range-wide synthesis to evaluate geographic variation in life history traits, 2) critically needed demographic estimates, population viability analysis, and prescribed burn simulations from a centrally located population, and 3) a predictive hibernation ingress/egress model to assist managers in minimizing mortality during ground-disturbing land management activities. To address life history data gaps, I compiled data from 47 study sites representing 38 counties across the range. I used multimodel inference and general linear models with geographic coordinates and annual climate normals as explanatory variables to clarify patterns of variation in life history traits. I found strong evidence for geographic variation in six of nine life history variables. Adult female snout-vent length and neonate mass increased with increasing mean annual precipitation. Litter size decreased with increasing mean temperature, and the size--fecundity relationship and age zero growth both increased with increasing latitude. The proportion of gravid females also increased with increasing latitude, but this relationship may be the result of geographically varying detection bias. Next, I used eight years of data and contemporary capture-recapture and matrix model methods to estimate population parameters for an Eastern Massasauga population near the range center of the species in Cass County, Michigan. From 2009--2016, 826 Eastern Massasaugas were captured 1,776 times. On average, sexual maturity occurred at age three in both sexes. Mean litter size was 7.6. Annual survival increased with increasing age (age zero=0.38, age 1=0.65, age 2=0.76, age ≥3 females=0.71), but declined slightly in age ≥3 males (0.66). Abundance estimates ranged from 84--140 adults and annual reproductive frequency was 0.44. Using these estimates, I developed a baseline population projection model to evaluate population persistence in Cass County and the degree to which increased mortality during spring, fall, and late fall prescribed burns might affect population growth 50 and 100 years into the future if current conditions persist. The baseline model, which incorporated current prescribed fire practices, indicated a stable population with only a 1% probability of extinction over 100 years, suggesting that management practices at this site are sustainable if they remain unchanged. Simulations of conservative increases in mortality due to fire changed the probability of extinction little over 50 years (0.000--0.003), but increased probability of extinction up to 14% over 100 years in the most pessimistic prescribed burn scenario. Last, I installed on-site weather stations at seven Eastern Massasauga study sites in Iowa, Illinois, Ohio (2 sites), and Michigan (3 sites). I identified dates of spring emergence using a combination of intensive visual searches, radio telemetry, and camera traps. I used observation data and soil temperature data from logging stations to validate a predictive egress phenology model and clarify geographic patterns of variation in the timing of Eastern Massasauga emergence. Emergence from hibernation was clearly associated with a reversal in soil temperature gradients although there were sometimes multiple reversals with hibernation egress lagging the first reversal by a week or more. Based on these patterns, I provide recommendations that minimize the risk for Eastern Massasauga mortality and avoid unnecessary curtailment of the burn season. This model has the potential to predict when prescribed fire or ground-disturbing management activities are least likely to cause direct snake mortality.
Author: Eric Mitchell McCluskey
Publisher:
ISBN:
Category :
Languages : en
Pages : 111
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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 populations distributed across the lower third of Michigan. The Michigan SDM selected the topographic position index at a 1 km scale as the best predictor variable. This index uses a digital elevation model to provide information on relative peaks or valleys depending the scale of analysis. Importantly, this variable identified the low lying areas more prone to accumulate water and exhibit the moist conditions Massasauga prefer. The widespread distribution of Massasauga populations in Michigan also presented the opportunity to assess habitat availability and connectivity. Using the HSM from the Michigan SDM, I quantified the number of large, contiguous habitat patches and their protected status. Most were located on private land holdings. I compared least cost path (LCP) distances and distance-weighted metrics using three different resistance layers. I found LCPs based on raw HSM values were shorter than class-weighted HSM or land cover based resistance layers. Therefore conservation planners need to carefully consider the underlying resistance layers they use for connectivity based decisions. I also generated a range-wide SDM under different climate change scenarios to provide a future perspective on Massasauga conservation and evaluate potential shifts in habitat suitability and identify at-risk populations. The climate SDM indicated that southern Massasauga populations appear more at risk to changing conditions that may be unfavorable to the species.
Author: Scott Anthony Martin
Publisher:
ISBN:
Category : Massasauga
Languages : en
Pages : 0
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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 meters in the last three generations. This is despite known movements of over 2 km by individual snakes in other populations of this species found in more continuous habitat. From these results, I concluded that S. catenatus in NE Ohio is split into five genetically distinct populations in an area smaller than 15 km2 with no recent connectivity. (2) What landscape features drive the observed lack of connectivity? I next used the same SNP dataset with a second SNP dataset collected from 103 S. catenatus from a large population in Central Ohio to model landcover features that potentially impact resistance to movement between local habitat patches. I found that an inherent landscape feature, elevation, and contemporary landcover, specifically roads, were the main barriers to connectivity. I then used the resistance maps and pedigrees for S. catenatus populations in NE Ohio and Central Ohio to estimate the resistance values between all pairs of closely related individuals and used those to estimate dispersal kernels around each population. The kernels results reinforced our previous finding of no contemporary connectivity between S. catenatus populations in this region. (3) How would proposed management actions impact the demographic viability of S. catenatus in NE Ohio? The habitat occupied by populations of S. catenatus in NE Ohio has been targets of active management to prevent vegetation succession, and there has been increased interest in additional habitat management. Suggested management actions for individual S. catenatus populations have focused on increasing habitat sizes, increasing the frequency of woody vegetation removal, creating habitat between populations, and translocating snakes between populations. I built forward-in-time simulations of population trends under current management and five alternative management activities using resistance maps that I previously developed in Population Viability Analysis (PVA) models. I found that connectivity improvements via the formation of new habitats (and ideally new populations) between the current populations or a hybrid connectivity/translocation strategy offered the greatest improvement towards both overall population size and the number of occupied patches. These connectivity models were superior to the base scenario representing no changes to management. Overall, my research has generated novel tools and approaches based on landscape genetics and demographic modeling for conservation of endangered and threatened species in fragmented landscapes. When applied to S. catenatus population is in NE Ohio, these approaches have provided new and significant insights on contemporary population structure in S. catenatus in NE Ohio, how the landscape created the observed patterns, and how this information can be used to generate management recommendations to promote the long-term persistence of this threatened reptile.
Author: Stephanie Anne Shaffer
Publisher:
ISBN: 9780438337671
Category : Electronic dissertations
Languages : en
Pages : 190
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Author: Lisa Ann Hallock
Publisher:
ISBN:
Category : Massasauga
Languages : en
Pages : 106
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Author: Rebecca Ann Christoffel
Publisher:
ISBN:
Category : Eastern massasauga
Languages : en
Pages : 612
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Author: National Park Service
Publisher: CreateSpace
ISBN: 9781492156840
Category : Nature
Languages : en
Pages : 54
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The eastern massasauga rattlesnake (Sistrurus catenatus catenatus) is a candidate for federal listing as a threatened or endangered Distinct Population Segment (DPS) (U.S. FWS 2003). Although the massasauga rattlesnake is thought to be in decline throughout much of its range, only the eastern subspecies (Sistrurus c. catenatus) is currently under consideration for listing. The eastern subspecies has been described as historically ranging from central New York and southern Ontario, southwest to Iowa and Missouri (Johnson 1995; Minton 2001). This eastern subspecies encompasses all S. catenatus residing north and east of the Missouri River.
Author: Matthew David Cross
Publisher:
ISBN:
Category : Eastern massasauga
Languages : en
Pages : 82
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