I investigate aspects of fleet dynamics in a mobile gear, groundfish fishery, on the Scotian Shelf; an area subject to a seasonal area closure. Firstly, the direct impacts of the closure on the redistribution of fishing effort and the resultant catch rates of those “fishing the line” (FTL) were examined. Effort was found to concentrate within 30km of the closure boundary. Two areas of potential FTL strategy were identified, which produced variable catch rate trends. East of the closure, areas of highest catch rate corresponded to areas of greatest effort, while to the west, catch rate was often equalized throughout the region, analogous to the ideal free distribution (IFD). Secondly, two effort distributional models were compared: an IFD-based isodar model and a discrete choice model. The isodar was determined to be the preferred model because of both its consistently superior predictive performance and its greater simplicity.

I investigate aspects of fleet dynamics in a mobile gear, groundfish fishery, on the Scotian Shelf; an area subject to a seasonal area closure. Firstly, the direct impacts of the closure on the redistribution of fishing effort and the resultant catch rates of those “fishing the line” (FTL) were examined. Effort was found to concentrate within 30km of the closure boundary. Two areas of potential FTL strategy were identified, which produced variable catch rate trends. East of the closure, areas of highest catch rate corresponded to areas of greatest effort, while to the west, catch rate was often equalized throughout the region, analogous to the ideal free distribution (IFD). Secondly, two effort distributional models were compared: an IFD-based isodar model and a discrete choice model. The isodar was determined to be the preferred model because of both its consistently superior predictive performance and its greater simplicity.

The main proponent of management of any animal species is habitat management. The ability of habitats to maintain species communities will depend on the variation in both habitat structure and composition. While spatial variation in habitat resources plays a critical role in determining the distribution of species, an equally important consideration that must be accounted for is temporal variation in the needs of the target species. Nutritional requirements, and thus the habitats used to fulfil those nutritional needs, will be different depending on if the individual is breeding, migrating, molting, enduring winter, or establishing a new range. For waterfowl, we currently assume that winter and migration are nutritionally stressful and are consequently the periods most limiting to populations. The theory of ideal free distribution assumes that animals distribute themselves according to the factor most limiting to their fitness. In the case of non-breeding waterfowl, this factor is believed to be food. We assume if habitats with abundant food resources are provided, waterfowl will make use of those habitats. Deviations from an ideal free distribution based on food become problematic for managers since these deviations will keep some areas from being exploited to their potential, while other areas may become over-exploited. Recent observations have made it clear that this assumption may need to be reconsidered for effective waterfowl management. In this dissertation I quantitatively examine the degree to which spring migrating waterfowl conform to, or deviate from, an ideal free distribution based on food. Since food availability was not expected to account for 100% of waterfowl distribution, I further investigated what other potential habitat components influence the distribution of spring migrating waterfowl. In the first chapter of this dissertation, I explicitly tested the influence of food availability on waterfowl distribution. A series of paired 0.42 ha (1 acre) plots were established in various habitat types. One plot in each pair was treated with corn to a density of 2000 kg/ha, while the remaining plot was used as a control. Background food availability was controlled for by taking core samples from each plot, and estimating the natural seed and invertebrate biomass. The abundance each species of waterfowl using the plots was recorded during morning and afternoon observation periods. Linear mixed models were used to assess how variations in food availability influenced distribution of waterfowl. Although the waterfowl community showed a significant preference for treatment plots, our ability to influence abundance was low. Food availability accounted for minimal variation in abundance of the waterfowl community as a whole or for each focal species. Since the results of the first chapter showed food availability to be a poor predictor of waterfowl distribution, in the second chapter I set out to determine other potential habitat variables could be responsible for driving waterfowl distribution during spring migration. After each observation period, a series of habitat structural measurements were made within each paired plot. Habitat measurements included water characteristics, vegetation structure, vegetation type, habitat type, and weather conditions. Linear mixed models and model selection were employed to determine which of the habitat characteristics showed the greatest ability to predict waterfowl abundance on study plots. Models containing precipitation and Wabash River flood stage predictor variables were the best performing, and were the best predictors of waterfowl abundance on study plots. The results from this chapter encouraged investigation into how environmental factors shape the formation of local duck communities are structured from regional pools. In the third chapter of this dissertation I investigate the relationship between local and regional waterfowl community structure and how this relationship is mediated through environmental filters which dictate what proportion of the regional species pool exists at local scales. To address this relationship, I tested three hypotheses: 1) resource availability drives species diversity at local scales; 2) similarity between local and regional habitats will result in a similar species community occurring at both scales, and; 3) increased heterogeneity of local habitat structure will result in more diverse waterfowl communities at local scales. I used Mahalanobis distance and cumulative standard deviation of habitat variables in conjunction with mixed models and model selection to compare hypotheses and determine which had the greatest potential for mediating local community structure from regional pools. Increasing resource abundance appeared to have the greatest influence over local duck diversity, but the model indicated that although species diversity could be increased by increasing food abundance, diversity at local scales would become saturated before becoming representative of the regional community.

Explaining spatial and temporal variation in the abundance of species is one of the primary goals of ecology. Habitat selection, the behaviour that organisms use to choose habitat patches that maximize fitness, can explain patterns in abundance between patches at small spatial scales within the dispersal capacity of the species. However, habitat selection models assume there is a reduction in individual fitness as population density increases due to increased competition between individuals. Ectotherms, which often select habitats based on temperature, a density-independent resource, may not display density-dependent responses if temperature limits energy assimilation more than finite food resources limit energy acquisition. As predicted by their dependence on environmental temperatures, some ectotherms select habitat largely independently of population density when temperatures are far from the optimal temperature for performance. But, is density-dependence prevalent in ectotherm populations when temperatures are close to the optimal temperature for performance? Habitat selection models also assume that all individuals of a population exhibit the same strategy for maximizing fitness through habitat selection. However, differences in morphology and behaviour (e.g., reproductive strategy) can modify the optimal habitat selection strategy for different phenotypes. Finally, observed patterns in habitat selection and abundance can also be modified by competition with other species. Quantifying the relative importance of these different factors that affect habitat selection behaviour will improve our ability to predict the spatial distribution and relative abundance of organisms. The objective of my thesis was to explain spatial variation in the abundance of ectotherms, using the ornate tree lizard (Urosaurus ornatus) as a study species. In chapter one, I tested whether density-dependent habitat selection explained patterns in abundance and fitness of lizards between two habitats differing in suitability. In chapter two, I tested whether density dependent habitat selection in tree lizards was caused by intraspecific competition for food that limited body size and growth. In chapter three, I tested whether variation in reproductive strategy, as indicated by throat colour phenotype, affected space use and habitat selection in male tree lizards. Finally, in chapter four, I tested whether interspecific competition with another lizard species affected habitat selection, fitness, and abundance of tree lizards. My thesis emphasizes the importance of intraspecific competition in shaping patterns of habitat selection and abundance in terrestrial ectotherms. I show that habitat selection is strongly density-dependent despite differences in thermal quality between habitats. I show that density-dependent mortality and growth lower the fitness of individuals when populations reach high densities, and this likely caused habitat selection to be density-dependent. Despite this evidence for density-dependent habitat selection, I show considerable variation between individuals in habitat selection and space use. Males with different throat colour phenotypes select habitats differently, demonstrating that variation in morphology can influence habitat selection patterns within a population. Finally, I show that interspecific competition with another lizard affects space use and how frequently tree lizards switch habitats, but this does not lead to differences in fitness or in the relative abundance of tree lizards in habitats. Therefore, intraspecific competition for resources was the dominant force shaping the relative abundance of tree lizards in different habitats.

Archaeologists describe the Uinta Fremont (A.D. 0 – 1300) as a mixed foraging-farming society that underwent a dramatic social change from A.D. 700 – 1000. Researchers observe through different architectural styles and subsistence activity a change from large, aggregated settlements to more dispersed and defensively oriented villages and hamlets. The Ideal Free Distribution (IFD) model provides an explanatory framework through which to interpret these changes. IFD predicts the order in which people or animals will occupy habitats based on a habitat’s relative suitability and suggests hypothetical behaviors that people or animals might engage in to improve or maintain the relative suitability of a habitat. One prediction of IFD is that behaviors indicating resource competition will become more frequent when population density increases. I test whether this hypothesis explains changes in storage features by considering storage behavior as a manifestation of resource competition, and I investigate whether storage feature frequency correlates with periods of Fremont population increases and paleoenvironmental degradation. These tests explain aspects of Fremont culture change and suggest future research possibilities. Storage feature frequency, representing resource competition, remains low from A.D. 0 – 700, suggesting that the habitats could absorb growing Fremont populations. After A.D. 700, however, resource competition rose and remained high, a condition that likely spurred the defensive architecture and dispersed settlements that became increasingly common after A.D. 1000. The successes and limitations of applying IFD to the archaeological record point the way toward future uses of the model to investigate settlement spacing and reaffirm the use of radiocarbon data in archaeological science.

Indoor spaces have become increasingly prevalent in human lives. While scholarship in other fields has studied the relationship between humans and the indoors, it has not been readily investigated in Geography. This study draws from prior research in Building Design, Managerial Science, and Education to examine the relationship between building users and resources in indoor spaces. To better understand how users seek resources in an indoor, academic space, this research asks: (1) what spaces and resources do building users value?; and (2) how are their perceptions of value associated with observed measures of occupancy? This research takes place in Goodwin Hall, on the Blacksburg campus of Virginia Polytechnic Institute and State University. This research relies on surveys conducted in 2018 as well accelerometer data collected in 2018 to examine the relationship between users' perception and use of resources in informal learning environments. Through quantitative analysis this research tests the ideal free distribution hypothesis. Findings indicate that certain measures of use and value support the ideal free distribution hypothesis. These results help to lay a groundwork for future geographic research in indoor spaces. / Master of Science / Indoor spaces have become increasingly created, used, and occupied by humans. Geography, as a discipline, has traditionally studied the relationship that humans have with their surrounding outdoor environments. This research studies how humans interact with their indoor environments. Other disciplines, such as Building Design, Managerial Science, and Education have examined how indoor spaces can impact human movement, behavior, and choice. Geography is a spatial discipline (observes how variables affect each other over space) and offers a differing lens to view human-indoor relationships. To better understand how users seek resources in an indoor, academic space, this research asks: (1) what spaces and resources do building users value?; and (2) how are their perceptions of value associated with observed measures of occupancy? This research takes place in Goodwin Hall, on the Blacksburg campus of Virginia Polytechnic Institute and State University. This research relies on surveys conducted in 2018 as well accelerometer data, which observes the amount of acceleration, collected in 2018 to examine the relationship between how users' view and use resources and spaces within an indoor environment. Through quantitative analysis this research tests the ideal free distribution hypothesis. Findings show that certain measures of use and value support the ideal free distribution hypothesis. Findings from this paper help to provide more insight into how humans interact with indoor spaces and lays the groundwork for future indoor geographic research.

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Amphibian populations are declining globally due to a litany of factors including pollution, disease, climate change, and most importantly, habitat destruction. As most amphibian life histories involve their populations being recruitment limited, focusing on the mechanism behind breeding habitat selection will reveal useful cues that managers may use to increase abundance and breeding success. Though there are many theoretical models that describe the distribution of animals in response to a resource, the ideal free distribution (IFD) theory has not yet been applied to amphibian settling decisions. Through this application of the IFD, I have found that a population of wood frogs (Lithobates sylvaticus) in Patuxent National Wildlife Refuge select vernal pools that are large, deep, and hold water into the summer months to breed from 2010-2015. This information will provide managers with the ability to predict sites where wood frogs will breed in the future, as well as describe the cues that wood frogs are cueing in on so we can protect, alter, or create ideal breeding habitat.

The hierarchical levels at which resource selection occurs can have important consequences for individual and population energy budgets and structure the impacts of a forager on its ecosystem. Assessing factors affecting resource selection of large marine herbivores across scales is important because of their potentially large impacts on seagrass community dynamics and historical and current changes in their population sizes and those of their potential predators. I explored the factors (predation risk, resource abundance, quality and identity) affecting resource use of large marine herbivores (green turtles, Chelonia mydas) from the scale of habitat patches to forage species within patches. I used a combination of in-water surveys, aerial drone video transects, baited camera surveys, and seagrass community and nutrient content analyses to provide insights into resource use by turtles in multiple ecological contexts. In Abaco, The Bahamas I found relatively intact shark populations, including apex predators, relative to other parts of the Caribbean. In the context of healthy predator populations in Abaco, I tested a priori predictions rooted in Ideal Free Distribution (IFD) theory. Green turtles off Abaco deviated from predictions of an IFD determined by the standing stocks of seagrass. Instead, distributions are consistent with predictions of the foraging arena hypothesis with turtles largely restricted to safe habitat patches and selecting locations within these where seagrass N content is relatively high. Marine invasive species can have detrimental effects on coastal ecosystems and economies. Therefore, understanding the effects of, and factors influencing the rate of spread of the invasive seagrass Halophila stipulacea in the Caribbean is important. In the French West Indies (Guadeloupe, Martinique and St. Martin), I investigated foraging preferences for native versus invasive seagrass species and whether green turtles might facilitate or attenuate the invasion through their choice of habitats and feeding patterns. Green turtle distributions were correlated with native seagrass distributions. Also, despite similar nutrient contents, turtles preferred feeding on native seagrasses irrespective of their relative abundance within a patch. These results suggest that, as predicted by the Enemy Release Hypothesis, green turtles likely facilitate the invasion and spread of the invasive seagrass that may reduce energy flow into turtle populations.