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Lora L. Smith

Publications and source records attributed to Lora L. Smith.

7 recordsLinked to original sources

Module 4: Basic biology of wetland animals

An assortment of animals inhabit wetlands, with many invertebrates, amphibians and reptiles, fishes, birds, and some mammals being wetland specialists. Wetlands provide ample water, food, and cover that benefits resident animals, but periodic high floods, frequent drying, and harsh water qualities (low-oxygen, acidic, saline) can stress wetland animals. Animals that rely on wetlands have developed numerous adaptations to cope with these stresses. The animal biodiversity in wetlands is particularly valued by people, from deep historical and cultural connections, to modern ecotourists and bird watchers who observe it and hunters and anglers who appreciate the consumptive resources they provide. Animals such as alligators and beavers create or physically-modify wetland environments; this activity is called ecosystem engineering and makes these animals among the most important organisms to wetland ecology. Wetlands are high in biodiversity and support rich communities of wetland invertebrates, are primary breeding habitats for most amphibians, and nearly all migratory birds rely on wetlands during some part of their annual cycle. The interactions of animals with plants (herbivory, cutting) and each other (predation) strongly shape wetland environments and affect nutrient cycling. Human impacts on wetlands can negatively affect many animals through habitat loss and degradation, resulting in many wetland amphibians, reptiles, and birds being listed as threatened and endangered species. Thus, wetland conservation is vital to conserve many animal species.

Wetland Science & Practice

Simulation modeling to assess line transect distance sampling under a range of translocation scenarios

The accuracy of posttranslocation population monitoring methods is critical to assessing long-term success in translocation programs. Translocation can produce unique challenges to monitoring efforts; therefore, it is important to understand the flexibility and robustness of commonly used monitoring methods. In Florida, USA, thousands of gopher tortoises Gopherus polyphemus have been, and continue to be, translocated from development sites to permitted recipient sites. These recipient sites create a broad range of potential monitoring scenarios due to variability in soft-release strategies, habitat conditions, and population demographics. Line transect distance sampling is an effective method for monitoring natural tortoise populations, but it is currently untested for translocated populations. We therefore produced 3,024 individual-based, spatially explicit scenarios of translocated tortoise populations that differed in recipient site and tortoise population properties, based on real-world examples, literature review, and expert opinion. We virtually sampled simulated tortoise populations by using line transect distance sampling methods and built a Bayesian hierarchical model to estimate the population density for each simulation, which incorporated individual-level covariates (i.e., burrow width and burrow occupancy). Line transect distance sampling was largely appropriate for the conditions that typify gopher tortoise recipient sites, particularly when detection probability on the transect lines was greater than or equal to 0.85. Designing the layout of transects relative to the orientation of soft-release pens, to avoid possible sampling biases that lead to extreme outliers in estimates of tortoise densities, resulted in more accurate population estimates. We also suggest that use of individual-level covariates, applied using a Bayesian framework as demonstrated in our study, may improve the applicability of line transect distance sampling surveys in a variety of contexts and that simulation can be a powerful tool for assessing survey design in complex sampling situations.

Florida

Accounting for spatial heterogeneity in visual obstruction in line-transect distance sampling of gopher tortoises

Line-transect distance sampling (LTDS) surveys are commonly used to estimate abundance of animals or objects. In terrestrial LTDS surveys of gopher tortoise ( Gopherus polyphemus ) burrows, the presence of ground-level vegetation substantially decreases detection of burrows of all sizes, but no field or analytical methods exist to control for spatially heterogeneous vegetation obstruction as a source of variation in detection. We propose the addition of a simple measurement of ground-level vegetation that serves as a covariate for the detection function. We present a Bayesian hierarchical model in which covariates burrow width and nearby vegetation height help to account for detection bias and improve precision of estimated density. We investigate the performance of this covariate by simulation and by using real LTDS data collected before and after application of prescribed fire. We collected data in 2018 at the Jones Center at Ichauway in Newton, Georgia, USA. Across all simulations, our model including both covariates produced the most accurate density point estimates of any of the models tested. For our case study, our Bayesian model with vegetation covariates tended to produce similar estimates of density before and after burns. Our study indicates that any level of spatial variation in vegetation obstruction decreases detection of burrows and may lead to underestimation in population size (≤68%) and proportion of individuals with small burrow sizes (≤32%) when not considered during analysis. Our work is extensible to other terrestrial sampling efforts where systematic measurement of a spatially distributed obstructing feature is feasible during the LTDS survey.

Georgia

Biological connectivity of seasonally ponded wetlands across spatial and temporal scales

Many species that inhabit seasonally ponded wetlands also rely on surrounding upland habitats and nearby aquatic ecosystems for resources to support life stages and to maintain viable populations. Understanding biological connectivity among these habitats is critical to ensure that landscapes are protected at appropriate scales to conserve species and ecosystem function. Biological connectivity occurs across a range of spatial and temporal scales. For example, at annual time scales many organisms move between seasonal wetlands and adjacent terrestrial habitats as they undergo life‐stage transitions; at generational time scales, individuals may disperse among nearby wetlands; and at multigenerational scales, there can be gene flow across large portions of a species’ range. The scale of biological connectivity may also vary among species. Larger bodied or more vagile species can connect a matrix of seasonally ponded wetlands, streams, lakes, and surrounding terrestrial habitats on a seasonal or annual basis. Measuring biological connectivity at different spatial and temporal scales remains a challenge. Here we review environmental and biological factors that drive biological connectivity, discuss implications of biological connectivity for animal populations and ecosystem processes, and provide examples illustrating the range of spatial and temporal scales across which biological connectivity occurs in seasonal wetlands.

Journal of the American Water Resources Associatio

The effect of coachwhip presence on body size of North American racers suggests competition between these sympatric snakes

When sympatric species compete, character divergence may help maintain coexistence. Snakes are often found in species-rich assemblages while exploiting similar resources; because snake body size is a relatively plastic trait that determines the range of prey sizes an individual may consume, divergence in body size between sympatric species may arise as a result of interspecific interactions. The North American racer, Coluber constrictor, and the larger coachwhip, Coluber flagellum, have a close taxonomic relationship and similar foraging strategies. Therefore, we hypothesized that C. constrictor would be smaller where they co-occur with C. flagellum, as compared to where C. flagellum is absent, throughout the southeastern extent of their range. To evaluate this hypothesis, we obtained data on body size for 2321 adult C. constrictor and 526 adult C. flagellum, along with habitat data and other potentially important factors influencing body size. Coluber constrictor was smaller than elsewhere when in peninsular Florida, in pine forests, on hydric soils and in the presence of the larger and potentially competing C. flagellum. Body size of C. flagellum did not vary by any measured habitat variables. The trends we documented are consistent with the hypothesis that C. constrictor body size is influenced by several variables, including co-occurrence with C. flagellum.

Alabama;Florida;Georgia;Louisiana;Mississippi;Sout

Status and distribution of the angonoka tortoise ( Geochelone yniphora ) of western Madagascar

From 1993 to 1995, field surveys were conducted in western Madagascar to assess the current status of the angonoka tortoise ( Geochelone yniphora ) in the wild. Tortoise presence was documented at 10 of 11 localities surveyed. These localities represent at least five populations, all within a 30-km radius of Baly Bay, near the town of Soalala. The populations occur on fragments of habitat ranging from <50 to 4&ndash;6000 ha in size. One hundred and forty-five tortoises were marked in the five populations. Hatchling or juvenile tortoises were observed in all populations, indicating that reproduction was occurring. Most of the 145 tortoises (68%) were marked on Cape Sada, where monthly surveys were conducted. The tortoise density on the c. 150 ha peninsula was 0.66 tortoises/ha. The remains of 22 dead juveniles were found on Cape Sada over the 2-year period. This evidence, combined with the low number of juveniles in intermediate size classes in the Cape Sada population suggests that juvenile mortality may be high.

Biological Conservation