Thesis (M.S.)--Bowling Green State University, 2008. / Document formatted into pages; contains x, 78 p. Includes bibliographical references.

Thesis (Ph.D.)--Bowling Green State University, 2007. / Document formatted into pages; contains xii, 121 p. : maps. Includes bibliographical references.

Thesis(M.S.) --Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Mode of access: World Wide Web. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 136-146). / Electronic reproduction. / Also available by subscription via World Wide Web / 146 leaves, bound ill. 29 cm

Includes bibliographical references.

Thesis (M.Sc. Biological Sciences)--University of Waikato, 2007. / Title from PDF cover (viewed April 7, 2008) Includes bibliographical references (p. 91-101)

abstract: The southwestern willow flycatcher (Empidonax traillii extimus) is listed as an endangered species throughout its range in the southwestern United States. Little is known about its sub-population spatial structure and how this impacts its population viability. In conjunction with being listed as endangered, a recovery plan was produced by the US Fish and Wildlife Service, with recovery units (sub-populations) roughly based on major river drainages. In the interest of examining this configuration of sub-populations and their impact on the measured population viability, I applied a multivariate auto-regressive state-space model to a spatially extensive time series of abundance data for the southwestern willow flycatcher over the period spanning 1995-2010 estimating critical growth parameters, correlation in environmental stochasticity or "synchronicity" between sub-populations (recovery units) and extinction risk of the sub-populations and the whole. The model estimates two parameters, the mean and variance of annual growth rate. Of the models I tested, I found the strongest support for a population model in which three of the recovery units were grouped (the Lower Colorado, Gila Basin, and Rio Grande recovery units) while keeping all others separate. This configuration has 6.6 times more support for the observed data than a configuration assigning each recovery unit to a separate sub-population, which is how they are circumscribed in the recovery plan. Given the best model, the mean growth rate is -0.0234 (CI95 -0.0939, 0.0412) with a variance of 0.0597 (CI95 0.0115, 0.1134). This growth rate is not significantly different from zero and this is reflected in the low potential for quasi-extinction. The cumulative probability of the population experiencing at least an 80% decline from current levels within 15 years for some sub-populations were much higher (range: 0.129-0.396 for an 80% decline). These results suggest that the rangewide population has a low risk of extinction in the next 15 years and that the formal recovery units specified by the original recovery plan do not correspond to proper sub-population units as defined by population synchrony. / Dissertation/Thesis / M.S. Biology 2012

Swamp rabbits (Sylvilagus aquaticus) in southern Illinois exist as a metapopulation due to loss and fragmentation of the bottomland hardwood forests in which they live, making their persistence in the state uncertain. I ran a spatially-explicit population viability analysis (PVA) on the metapopulation, using a habitat suitability map I created and life history parameters drawn from the literature. I varied parameters related to reproduction, survival, catastrophes, dispersal, and carrying capacity from 50 to 150% of the initial value of each parameter to compare their effects on extinction risk. I modified the map to test the effects of potential habitat loss, fragmentation, and the addition of dispersal corridors on the swamp rabbit metapopulation in southern Illinois. Under baseline conditions, the model suggested about a 20% chance of quasi-extinction (90% metapopulation decline) in 25 years. Changes in fecundity values and the effects of catastrophic flooding had the greatest effect on the risk of extinction, causing quasi-extinction probabilities to range from 0 to 100% and 0 to 87%, respectively. In contrast, changing dispersal values yielded the least impact on the risk of extinction (18-24%), and all other parameters had moderate impacts on the model. Removing groups of the largest habitat patches increased the risk of extinction, whereas removing groups of the smallest habitat patches decreased the risk of extinction, suggesting that small patches could act as population sinks with a negative impact on swamp rabbit persistence. Decreasing patch fragmentation per se reduced the risk of extinction slightly. The addition of dispersal corridors made no significant impact on the probability of extinction. My findings indicate that more research estimating fecundity and the effect of catastrophic floods on swamp rabbits in Illinois is required to more accurately predict swamp rabbit persistence in the state. I also suggest that managers should work to decrease the effect of flooding on the population by improving upland habitat, or decrease fragmentation by increasing the area of bottomland hardwood forests around existing habitat patches. Lastly, I suggest managers focus on preventing further habitat fragmentation into small patches, which will mitigate the creation of potential sink populations and will enable current populations to persist.

Long-lived, top-level predators, such as some marine mammals, serve as important indicators of ecosystem health. Assessing the abundance and habitat use of such marine top predators is essential for the formulation of effective conservation and management actions. There is considerable concern over the viability of small humpback dolphin opulations across a global scale and a number of studies have raised concerns over their vulnerability to extinction. In light of the recent uplisting of Indian Ocean humpback dolphins (Sousa plumbea) to ‘Endangered’ on the South African Red Data list, there is an urgent need for a greater understanding of the abundance and spatial distribution of this species along the South African coastline. Using small vessels as survey platforms between March 2014 and June 2015, this study attempted to determine the abundance, spatial distribution and habitat preferences of Indian Ocean humpback dolphins along 150 km of South Africa’s south coast. A further aim was to assess the utilisation of the current Marine Protected Area network by humpback dolphins along this coastline relative to areas outside of formal protection. Mark-recapture methods applied to photo-identification data produced abundance estimates of 84 individuals (95% CI: 72-115) within the study area for both open and closed models. An average group size of 3.94 individuals (range 1-12; SD = ± 2.82) was observed during the study, indicating a decrease in average group size of ~45 % from a previous assessment in 2002/03. Such a decline in group size could potentially be a result of a change in social structure in response to reduced prey availability. Spatial analyses of humpback dolphin geographic positions, using a kernel density estimator (KDE) and effort-weighted density grid analyses, indicate that the species is unevenly distributed over the coastal zone within the area. Sightings occurred at the highest densities within Buffels Bay and along Goukamma MPA, followed by Plettenberg Bay, Nature’s Valley, and around the Bloukrans, Elandsbos and Groot River East mouths. Habitat preference was assessed using a standard classification-based method and the results indicate a strong preference, in particular, for Dissipative Intermediate Sandy Coast habitat, followed by Very Exposed Rocky Coast, Intermediate Sandy Coast, Estuarine Shore, Mixed Shore and Inshore Reef habitats. Areas of high humpback dolphin densities appear to be associated with these habitat types, especially with Dissipative-Intermediate Sandy Coast habitat. Humpback dolphins were sighted at relatively low densities along stretches of coastline consisting predominately of Exposed Rocky Shore habitat. Long expanses of this habitat type may limit humpback dolphin movements along the coast. The observed patterns in distribution and habitat preferences may be linked to the availability of prey and/or the avoidance of predators. Average sightings per kilometer travelled (SPUE) indicate that the utilisation of the Robberg and Tsitsikamma MPAs by humpback dolphins was low, most likely due to the low availability of sandy coastline in these areas. In contrast, the utilisation of the Goukamma MPA, which is characterised by a high availability of Dissipative-Intermediate Sandy Coast, was very high. The low population numbers and declines in average group size of Indian Ocean humpback dolphins within the study area warrant concern and call for effective conservation and management measures. In light of ever-increasing levels of anthropogenic threats to coastal areas, future research and long-term monitoring of the population is essential to broaden our knowledge of the species and to detect population trends.

Marine turtles produce many offspring which offsets the high mortality experienced by turtles during early development. Juvenile mortality might be reduced by evolving effective behavioral as well as morphological anti-predator defenses. Body proportions of three species (Caretta caretta, Chelonia mydas, Dermochelys coriacea) of turtles were measured in the first fourteen weeks of development to examine how growth may mitigate predation by gape-limited predators. Growth was categorized as isometric if shape did not change during development or allometric if body shape did change. All three species showed allometric growth in carapace width; however it was less pronounced in the larger D. coriacea turtles. Allometric growth in carapace width decreased as all three species grew in size. When high predation occurs in early development, many species will favor rapid growth into a size refuge. Juvenile sea turtles may optimize their survival by growing allometrically when predation risk is the greatest. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection