I compared the performance of habitat models created from data of differing reliability. Because the reliability is dependent on the probability of detecting the species, I experimented to estimate detectability for a salamander species. Based on these estimates, I investigated the sensitivity of habitat models to varying detectability. Models were created using a database of amphibian and reptile observations at Fort A.P. Hill, Virginia, USA. Performance was compared among modeling methods, taxa, life histories, and sample sizes. Model performance was poor for all methods and species, except for the carpenter frog (Rana virgatipes). Discriminant function analysis and ecological niche factor analysis (ENFA) predicted presence better than logistic regression and Bayesian logistic regression models. Database collections of observations have limited value as input for modeling because of the lack of absence data. Without knowledge of detectability, it is unknown whether non-detection represents absence. To estimate detectability, I experimented with red-backed salamanders (Plethodon cinereus) using daytime, cover-object searches and nighttime, visual surveys. Salamanders were maintained in enclosures (n = 124) assigned to four treatments, daytime__low density, daytime__high density, nighttime__low density, and nighttime__high density. Multiple observations of each enclosure were made. Detectability was higher using daytime, cover-object searches (64%) than nighttime, visual surveys (20%). Detection was also higher in high-density (49%) versus low-density enclosures (35%). Because of variation in detectability, I tested model sensitivity to the probability of detection. A simulated distribution was created using functions relating habitat suitability to environmental variables from a landscape. Surveys were replicated by randomly selecting locations (n = 50, 100, 200, or 500) and determining whether the species was observed, based on the probability of detection (p = 40%, 60%, 80%, or 100%). Bayesian logistic regression and ENFA models were created for each sample. When detection was 80 __ 100%, Bayesian predictions were more correlated with the known suitability and identified presence more accurately than ENFA. Probability of detection was variable among sampling methods and effort. Models created from presence/absence data were sensitive to the probability of detection in the input data. This stresses the importance of quantifying detectability and using presence-only modeling methods when detectability is low. If planning for sampling as an input for suitability modeling, it is important to choose sampling methods to ensure that detection is 80% or higher. / Ph. D.

The southeastern United States is a global biodiversity hotspot but has experienced severe declines of natural ecosystems. The southeast is currently facing widespread change, particularly from an increasing human population and climate change, that is likely to impact all remaining natural areas to some degree. In this work, I examine some of the challenges currently facing imperiled species of reptiles and amphibians in this region. The work is focused on two species, the Reticulated Flatwoods Salamander (Ambystoma bishopi) and the Eastern Indigo Snake (Drymarchon couperi) both of which are listed on the U.S. Endangered Species List. Chapter 1 used Light Detection and Ranging (LiDAR) data to measure wetland bathymetry (basin shape) in flatwoods salamander breeding wetlands. Bathymetry data were used to construct stage–area relationships for each wetland, and a history of water level monitoring data were applied to these relationships to build multi-year time series of flooded area metrics. These metrics were then combined with an assessment of vegetation characteristics to map potentially suitable habitat for flatwoods salamander breeding within each wetland. Chapter 2 focused on flatwoods salamander phenology (the timing of life history events) in response to climate change. I quantified flatwoods salamander movements into and out of breeding wetlands over a 10-year period (2010–2020), identifying temperature and precipitation patterns that were conducive to salamander movements. I then used future climate projections to forecast movement opportunities for flatwoods salamander from 2030–2099 and used an existing hydrologic model built on the same climate data to understand how phenology may interact with hydrology. Overall, only a small number of years are likely to have an ideal intersection of phenology and hydrology as has been observed during recent breeding seasons. Chapter 3 described the construction of a stochastic Integral Projection Model for flatwoods salamanders. I integrated the projections from Chapter 2 with the population model to estimate the viability of two flatwoods salamander populations from 2030–2099 under multiple climate change scenarios. The results indicated that approximately half of the examined scenarios resulted in a high probability (>0.5) of extinction when considering both wetland hydrology and salamander phenology. In Chapter 4, I described the creation of a stochastic Integral Projection Model for indigo snakes. I then demonstrated the utility of this model by examining the effects of initial population size, road density, and removal of individuals to support a captive colony on indigo snake populations. I found that high road densities and high collection rates would likely lead to population declines, although the rate of declines and extinction risk varied across scenarios. Taken together, these projects highlight some of the challenges currently facing herpetofauna in the southeastern United States, demonstrate the difficulty in conserving these often-overlooked species, and provide useful tools for ongoing conservation efforts focusing on these two imperiled species. / Doctor of Philosophy / We are in the midst of a global biodiversity crisis, with rates of species extinction far exceeding normal levels. Species loss is largely driven by global change attributable to human activities. A rapidly changing world can make it challenging to effectively conserve and manage imperiled species. In this work, I studied two species found only in the southeastern United States that are listed on the U.S. Endangered Species List. Chapters 1–3 focused on the Reticulated Flatwoods Salamander (Ambystoma bishopi), while Chapter 4 focused on the Eastern Indigo Snake (Drymarchon couperi). In Chapter 1, I used high resolution elevation data to map the shape of flatwoods salamander breeding wetlands. These data were then used to estimate flooded areas across multiple years. Flooded area metrics were combined with vegetation measurements to map potential flatwoods salamander breeding habitat. In Chapter 2, I examined how flatwoods salamander movements may respond to climate change. I identified time periods and weather conditions that coincided with flatwoods salamander movements into and out of breeding wetlands. I then projected potential movement opportunities based on multiple future climate scenarios for each breeding season from 2030–2099. My results showed that few years are likely to be ideal for flatwoods salamander reproduction, which is similar to trends observed in recent years. In Chapter 3, I built a population model for flatwoods salamanders. I then combined the model with predictions made in Chapter 2 to estimate the probability that populations would go extinct by the end of the century. The results indicated that the two flatwoods salamander populations examined had a high probability (>0.5) of extinction in about 50% of the climate scenarios. In Chapter 4, I constructed a population model for indigo snakes using a variety of available data. I used this model to examine the effects of road density, initial population size, and removal of individuals to support a captive colony on indigo snake populations. The results suggested that populations experiencing high road densities or high collection rates were likely to decline over time. These projects highlight some of the difficulties in conserving often-overlooked reptiles and amphibians in the southeastern United States and provide important tools for ongoing conservation projects working with these two imperiled species.

We examined the short-term (1 - 4 years postharvest) effects of 7 silvicultural treatments on terrestrial salamander populations at 4 sites in southwest Virginia and West Virginia. The 3 silvicultural treatments with the most canopy removal (4-7 m2 basal area Shelterwood, Leavetree, Clearcut) had significantly fewer salamanders than the control (p < 0.10) postharvest. No differences were found among treatments in age class distribution, the percent of females that were gravid, or average clutch size. We tested the nighttime, surface-count census method for visibility and behavior-induced bias among silviculture treatments and estimated the proportion of a salamander population that is active on the surface in harvested and control habitats. Instantaneous rates of salamander activity ranged from 1.3 to 11.7% of the population for redback (Plethodon cinereus) and slimy salamanders (P. glutinosus). Timber harvest caused up to a 2-fold increase or decrease in activity rates. There was evidence for bias in the night census method, but differences were not consistent enough to suggest general bias corrections. We also tested whether poorly fed salamanders exhibited risk-sensitive foraging in a dry environment in a laboratory experiment. Poorly fed salamanders were observed out of their simulated burrows less than well fed salamanders suggesting salamanders, particularly females and small adults, are risk-averse. / Master of Science

Habitat alteration (i.e. degradation, fragmentation, and destruction) is the primary driver of amphibian decline and extinction. Despite their ecological importance and threatened status, very little long-term research has been conducted on how methods of forest management impact salamanders. In this research, I examine how experimental silviculture impacts plethodontid salamander relative abundance and count, and I compare three different body condition indices. Chapter 1 focuses on plethodontid salamander relative abundance 30 years after experimental treatments (including clearcut and shelterwood harvests, understory herbicide, uneven-aged management, and an untreated control) were first applied. I found that plethodontid salamander populations in all silvicultural treatments without stand re-entry have reached pre-harvest relative abundance levels. Chapter 2 describes how artificial tip-up mounds that could be used to mimic old-growth forest characteristics impact plethodontid salamander count. Salamander count significantly declined in treatment units with artificial tip-up mounds but this could be an artifact of the heavy disturbance required for installation. Chapter 3 compares three different body condition indices for plethodontid salamanders. I found that bioelectrical impedance analysis (BIA) is likely not suitable for use with plethodontid salamanders and mass divided by snout-to-vent-length is likely a superior estimate to tail width divided by snout-to-vent-length. These findings further our understanding of how different forest management practices affect salamander populations and provide guidance for evaluating body condition. / Master of Science / Forest understory salamanders play an important role in energy transfer and their position in leaf litter food webs affects multiple ecosystem functions. Despite their ecological importance, very little long-term research has been conducted on how habitat change impacts salamanders. This research investigates how different forest management techniques influence forest-dwelling salamanders and compares three different ways to evaluate salamander health. Chapter 1 focuses on the salamanders 30 years post-harvest. I found that salamander populations in all silvicultural treatments except one had recovered. Chapter 2 described how tipping over trees to mimic old-growth forest characteristics impacts the number of forest-dwelling salamanders. There were significantly fewer salamanders in treatment units after the disturbance created by installing artificial tip-up mounds. Chapter 3 compares three different ways to evaluate forest-dwelling salamander health. I found that bioelectrical impedance analysis (BIA)is likely not suitable for forest-dwelling salamanders, and weight divided by body length is likely a superior estimate to tail width divided by body length. These findings together further our understanding of how different forest management practices affect salamander populations and provide guidance for evaluating body condition.

Mountaintop removal mining (MTR) is a notorious stressor of stream ecosystems in the Central Appalachians. Valley fills (VF) lead to reduced occupancy, abundance, and species richness of stream salamanders. Multiple factors may be responsible for these reductions, but specifically habitat fragmentation and degradation may reduce colonization rates and increase local extinction rates. From 2013-2015, repeated counts of salamanders were conducted in stream reaches impacted by MTR/VF and compared to counts in reference reaches to answer the question: do stream salamander population dynamics differ between stream reaches impacted by MTR/VF and reference stream reaches? I also investigated dynamics of stream habitat using measures relevant to stream salamander persistence. Accordingly, I examined number of cover objects, percent detritus, hydroperiod, and specific conductance. From the salamander capture data, colonization and survival probabilities were lower in MTR/VF reaches than reference reaches. MTR/VF reaches also had fewer cover objects, higher percent detritus, constant stream flow, and elevated specific conductance. Although specific conductance was increased in MTR/VF reaches, it was not strongly correlated with colonization and survival. I suggest reduced rates of colonization and survival in MTR/VF stream reaches are driven by inhibited dispersal and reduced individual survival due to degraded terrestrial and aquatic environments.

Bruce Peninsula National Park (BPNP) clears a 2 m swath of trees on the boundary in order to make it clear when one is entering the park from any neighbouring land; this in particular aims to protect the park and its inhabitants from illegal actions such as hunting and logging. This study looks at the ecological effects of this practice by measuring various microclimate variables and the abundance of eastern redback salamanders (Plethodon cinereus) on the boundary and comparing these measurements to parallel transects at 5, 10, 15, 20, and 40 m. Because it is a small linear development, it is then compared to other types of linear developments, such as roads, trails, and pipelines. The microclimate variables of air temperature, slug abundance, canopy cover, soil pH, total cover area, litter depth, and relative humidity were all significantly affected (p<0.05) up to 10 m into the adjacent forest, indicating that the cleared boundaries do change the surrounding microclimate. Soil pH, downed woody cover area, litter depth, and canopy cover were significantly affected (p<0.05) up to 5 m away from the boundary. Sixty hectares, or 0.4%, of the land area of BPNP is thus affected by the microclimate changes caused by the cleared boundary. These effects are similar to those found for other narrow, vegetated linear developments such as trails. Over double the number of salamanders were found on the boundary as compared to in the forest; this is due to higher cover area availability on the cleared boundary from the felled trees. Therefore, the boundary does not act as a barrier to eastern redback salamander movement, nor does it fragment the local population. Salamander abundance was best explained by the amount of cover area, snail abundance, and the dominant type of vegetation present along transects. It was also found in an additional study that salamander abundance tended to increase with increasing days since the last precipitation event, contrary to most woodland salamander monitoring protocols and methods. The boundaries were seen also to be used by hunters and recreationalists through incidental observations of human disturbance. This increased access to remote areas of the park through use of the cleared boundaries is an issue that requires further study, as the boundary itself may be leading to an increase in illegal activity. Recommendations to BPNP include leaving downed woody cover on the boundary, minimizing the boundary width, reducing lines of sight, decreasing accessibility, increasing landowner and park staff education, communicating with adjacent landowners, and securing funding to complete and maintain the boundary clearing.

Bruce Peninsula National Park (BPNP) clears a 2 m swath of trees on the boundary in order to make it clear when one is entering the park from any neighbouring land; this in particular aims to protect the park and its inhabitants from illegal actions such as hunting and logging. This study looks at the ecological effects of this practice by measuring various microclimate variables and the abundance of eastern redback salamanders (Plethodon cinereus) on the boundary and comparing these measurements to parallel transects at 5, 10, 15, 20, and 40 m. Because it is a small linear development, it is then compared to other types of linear developments, such as roads, trails, and pipelines. The microclimate variables of air temperature, slug abundance, canopy cover, soil pH, total cover area, litter depth, and relative humidity were all significantly affected (p<0.05) up to 10 m into the adjacent forest, indicating that the cleared boundaries do change the surrounding microclimate. Soil pH, downed woody cover area, litter depth, and canopy cover were significantly affected (p<0.05) up to 5 m away from the boundary. Sixty hectares, or 0.4%, of the land area of BPNP is thus affected by the microclimate changes caused by the cleared boundary. These effects are similar to those found for other narrow, vegetated linear developments such as trails. Over double the number of salamanders were found on the boundary as compared to in the forest; this is due to higher cover area availability on the cleared boundary from the felled trees. Therefore, the boundary does not act as a barrier to eastern redback salamander movement, nor does it fragment the local population. Salamander abundance was best explained by the amount of cover area, snail abundance, and the dominant type of vegetation present along transects. It was also found in an additional study that salamander abundance tended to increase with increasing days since the last precipitation event, contrary to most woodland salamander monitoring protocols and methods. The boundaries were seen also to be used by hunters and recreationalists through incidental observations of human disturbance. This increased access to remote areas of the park through use of the cleared boundaries is an issue that requires further study, as the boundary itself may be leading to an increase in illegal activity. Recommendations to BPNP include leaving downed woody cover on the boundary, minimizing the boundary width, reducing lines of sight, decreasing accessibility, increasing landowner and park staff education, communicating with adjacent landowners, and securing funding to complete and maintain the boundary clearing.

The number of California vernal pools and vernal lakes are diminishing. Through the present study, this investigator hopes to increase the understanding of vernal pool biota, as well as the awareness that these unique habitats need protection. Other studies of California vernal pools have emphasized their flora, their plankton and their physicochemical aspects. The purpose of this investigation is to survey the insects and other macrofauna found in two vernal lakes of eastern Stanislaus County, to examine the phenology of the insects within one of these lakes, and to compare the insect taxa found in these vernal lakes to those reported from studies of similar vernal pools.

The southern Appalachian Mountains have among the highest salamander diversity in the world, largely due to local speciation in the family Plethodontidae. Plethodontid salamanders (i.e., lungless salamanders) are particularly sensitive to habitat climate conditions due to their reliance on cutaneous respiration, and their immediate environmental conditions (microhabitat) likely influence their dispersion and activity more than the large-scale atmospheric conditions. The Northern Gray-cheeked salamander (Plethodon montanus) is restricted to high elevations in the Appalachian Mountains. Our goal was to investigate the relationship between P. montanus and its microhabitat by examining behavioral preference for climatic conditions, characterizing the microclimate with small-scale models, and testing for differences in stress hormones at different elevations. We found that behavioral preference is most restricted by relative humidity, microclimate models predicted far less prevalence at lower elevations than typical coarse-scale models, and stress hormones were elevated at a low elevation plot compared to a high elevation plot.

No description available.