Dissertations / Theses on the topic 'Foraging'

Bumble bees (bombus spp.) are significant pollinators of many plants, and are particularly attracted to mass-flowering crops such as Oilseed Rape (Brassica Napus), which they cross-pollinate. B. napus is both wind and insect-pollinated, and whilst it has been found that wind is its most significant pollen vector, the influence of bumble bee pollination could be non-trivial when bee densities are large. Therefore, the assessment of pollinator-mediated cross-pollination events could be important when considering containment strategies of genetically modified (GM) crops, such as GM varieties of B. napus, but requires a landscape-scale understanding of pollinator movements, which is currently unknown for bumble bees. I developed an in silico model, entitled HARVEST, which simulates the foraging and consequential inter-patch movements of bumble bees. The model is based on principles from Reinforcement Learning and Individual Based Modelling, and uses a Linear Operator Learning Rule to guide agent learning. The model incoproates one or more agents, or bees, that learn by ‘trial-and-error’, with a gradual preference shown for patch choice actions that provide increased rewards. To validate the model, I verified its ability to replicate certain iconic patterns of bee-mediated gene flow, and assessed its accuracy in predicting the flower visits and inter-patch movement frequencies of real bees in a small-scale system. The model successfully replicated the iconic patterns, but failed to accurately predict outputs from the real system. It did, however, qualitatively replicate the high levels of inter-patch traffic found in the real small-scale system, and its quantitative discrepancies could likely be explained by inaccurate parameterisations. I also found that HARVEST bees are extremely efficient foragers, which agrees with evidence of powerful learning capabilities and risk-aversion in real bumble bees. When applying the model to the landscape-scale, HARVEST predicts that overall levels of bee-mediated gene flow are extremely low. Nonetheless, I identified an effective containment strategy in which a ‘shield’ comprised of sacrificed crops is placed between GM and conventional crop populations. This strategy could be useful for scenarios in which the tolerance for GM seed set is exceptionally low.

Thesis (M.S.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed September 15, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 27-29).

Thesis (Ph. D.)--University of California, San Diego, 2010.
Title from first page of PDF file (viewed May 6, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

Charnov's (1976) marginal value theorem has had success in predicting that animals will optimize net rate of gain when foraging in a patchy environment. The present study attempts to apply the marginal value theorem (MVT) to human behavior in a business setting in 3 Experiments. Businesses also attempt to optimize net rate of gain when choosing to discontinue one product in lieu of another using a product life cycle (PLC). Experiments 1 & 2 attempted to assess human behavior in a business context by varying time necessary to retool and monetary cost of retooling respectively. Experiment 3 attempted to add ecological validity by introducing variability to the PLC. The results of Experiments 1, 2, & 3 indicate that the MVT does not accurately predict human behavior in a business context, though methodological issues may have affected these results. Future research must be conducted in this area.

All animals are adapted to the environmental conditions of the habitat they chose to live in. It was the aim of this PhD-project, to show which behavioral strategies are expressed as mechanisms to cope with the constraints, which contribute to the natural selection pressure acting on individuals. For this purpose, small mammals were exposed to different levels and types of predation risk while actively foraging. Individuals were either exposed to different predator types (airborne or ground) or combinations of both, or to indirect predators (nest predators). Risk was assumed to be distributed homogeneously, so changing the habitat or temporal adaptations where not regarded as potential options. Results show that wild-caught voles have strategic answers to this homogeneously distributed risk, which is perceived by tactile, olfactory or acoustic cues. Thus, they do not have to know an absolut quality (e.g., in terms of food provisioning and risk levels of all possible habitats), but they can adapt their behavior to the actual circumstances. Deriving risk uniform levels from cues and adjusting activity levels to the perceived risk is an option to deal with predators of the same size or with unforeseeable attack rates. Experiments showed that as long as there are no safe places or times, it is best to reduce activity and behave as inconspicuous as possible as long as the costs of missed opportunities do not exceed the benefits of a higher survival probability. Test showed that these costs apparently grow faster for males than for females, especially in times of inactivity. This is supported by strong predatory pressure on the most active groups of rodents (young males, sexually active or dispersers) leading to extremely female-biased operative sex ratios in natural populations. Other groups of animals, those with parental duties such as nest guarding, for example, have to deal with the actual risk in their habitat as well. Strategies to indirect predation pressure were tested by using bank vole mothers, confronted with a nest predator that posed no actual threat to themselves but to their young (Sorex araneus). They reduced travelling and concentrated their effort in the presence of shrews, independent of the different nutritional provisioning of food by varying resource levels due to the different seasons. Additionally, they exhibited nest-guarding strategies by not foraging in the vicinity of the nest site in order to reduce conspicuous scent marks. The repetition of the experiment in summer and autumn showed that changing environmental constraints can have a severe impact on results of outdoor studies. In our case, changing resource levels changed the type of interaction between the two species. The experiments show that it is important to analyze decision making and optimality models on an individual level, and, when that is not possible (maybe because of the constraints of field work), groups of animals should be classified by using the least common denominator that can be identified (such as sex, age, origin or kinship). This will control for the effects of the sex or stage of life history or the individual´s reproductive and nutritional status on decision making and will narrow the wide behavioral variability associated with the complex term of optimality.
Das Verhalten von Tieren ist das Ergebnis eines kontinuierlichen Anpassungsprozesses im Laufe der Evolution einer Art und damit der Veränderung der Umgebung in der es lebt und der Interaktion mit anderen Arten. Dies wird besonders deutlich im Verhalten von potentiellen Beutetieren, ihre Strategien beinhalten meist ein möglichst unauffälliges Verhalten im Zusammenspiel mit reduzierter Bewegung und möglichst guter Tarnung. Dementgegen stehen essentielle Bedürfnisse, wie zum Beispiel die Nahrungssuche, die Verteidigung von Ressourcen (zum Beispiel Territorien, Futterstellen) und die Suche nach Paarungspartnern. Beutetiere leben also in einem Spannungsfeld indem sie Ihr Verhalten optimieren müssen. Hierbei stehen die Ernährung, erfolgreiche Verpaarung und andere Chancen auf der einen Seite, die Vermeidung von Begegnungen mit Prädatoren auf der anderen. Vor allem Kleinsäuger sind häufig als Beutetiere mit einer Vielzahl von Prädatoren aus der Luft und auf dem Boden konfrontiert. Sie müssen für die verschiedenen Bedrohungen adaptive Verhaltensanpassungen bereit haben und in der Lage sein, auf die optischen, olfaktorischen oder akustischen Signale, die die Gefahr durch Prädatoren anzeigen, mit plastischen Verhaltensmustern zu reagieren. Die vorliegende Dissertation beschäftigt sich mit bisher als Konstanten behandelten Faktoren und untersucht anhand von Verhaltensexperimenten mit wilden Wühlmäusen (Microtus arvalis) folgende Fragestellungen: - Wie verhalten sich Tiere, die einer homogenen Risikoverteilung ausgesetzt sind, zum Beispiel weil ihr Prädator genauso gross ist wie sie, im gleichen Habitat lebt und es keinen sicheren Ort gibt? - Mit welchen Anpassungen reagieren Tiere, wenn sie gleichzeitig verschiedenen Prädatoren ausgesetzt sind? - Wie unterscheiden sich die Nahrungssuchstrategien von Männchen und Weibchen? - Wie verhalten sich laktierende Weibchen, die einer permanenten, indirekten Gefahr, z.B. durch einen Nestprädator ausgesetzt sind? Die Ergebnisse der verschiedenen Versuche in künstlichen Arenen und Aussengehegen zeigen, dass die Mäuse in der Lage sind, adaptive Verhaltensanpassung an homogenes Risiko und verschiedene Prädationstypen abzurufen. So sind sie in der Lage, Luft- von Bodenprädatoren zu unterscheiden und jeweils das Verhalten zu zeigen, dass die größtmögliche Sicherheit mit sich bringt. Die simultane Kombination von verschiedenen Prädatoren bewirkt hierbei additive Effekte. Gibt es keine Auswahl zwischen Habitaten, sondern nur unterschiedliche homogene Risikolevel, reagieren sie auf steigendes Risiko immer mit verminderter Aktivität und konzentrieren ihre Nahrungssuche auf weniger Futterstellen, beuten diese dafür jedoch länger aus. Die Wertigkeit von Futterstellen und alternativen Optionen verändert sich also mit dem Risikolevel. Ähnliches zeigt sich auch in den unterschiedlichen Futtersuchstrategien von Männchen und Weibchen. Die untersuchte Art ist polygyn und multivoltin, dementsprechend verbinden die Männchen mit ihrer Nahrungssuche Aktivitäten wie die Suche nach Paarungspartnern und unterscheiden sich die Aktivitätsmuster zwischen Männchen und Weibchen. Zusätzlich zeigen die Ergebnisse, das laktierende Weibchen in der Lage sind, das Risiko für sich und für Ihre Jungen abzuschätzen, wenn sie mit einem Nestprädator (Sorex araneus) konfrontiert werden. Für die Interaktion zwischen diesen beiden Arten ist jedoch die Saison (und damit die Ressourcenlage), in der sie sich begegnen, von entscheidender Bedeutung. Wühlmäuse reagieren mit entsprechenden Verhaltensanpassungen zum Schutz des Nestes um die Überlebenschancen ihrer letzten Würfe im Herbst zu erhöhen. Die vorliegende Arbeit konnte grundsätzliche Probleme der antiprädatorischen Verhaltensanpassung von Beutetieren klären und wichtige Faktoren der Entscheidungsfindung unter Prädationsdruck analysieren. Sie zeigt, dass Tiere das Risiko in ihrer Umgebung nicht unbedingt über direkt Signale wahrnehmen, sondern ihre Verhaltensstrategien einem empfundenen Gesamtrisikolevel anpassen. Dies ermöglicht ihnen, adaptive Strategien zu verfolgen, auch wenn sie keine Auswahl an sicheren Habitaten haben. Sie zeigt auch die unterschiedliche Wahrnehmung von Risiken durch Männchen und Weibchen, die durch die unterschiedlichen mit der Aktivität zusätzlich wahrgenommenen Chancen verknüpft zu sein scheint. Zusätzlich wurde der Einfluss des reproduktiven Status (z.B. laktierend), sowie der Ressourcenlage (z. B. je nach Saison) nachgewiesen.

In social insects, foraging is often cooperative, and so requires considerable organisation. In most ants, organisation is a bottom-up process where decisions taken by individuals result in emergent colony level patterns. Individuals base their decisions on their internal state, their past experience, and their environment. By depositing trail pheromones, for example, ants can alter the environment, and thus affect the behaviour of their nestmates. The development of emergent patterns depends on both how individuals affect the environment, and how they react to changes in the environment. Chapters 4 – 9 investigate the role of trail pheromones and route memory in the ant Lasius niger. Route memories can form rapidly and be followed accurately, and when route memories and trail pheromones contradict each other, ants overwhelmingly follow route memories (chapter 4). Route memories and trail pheromones can also interact synergistically, allowing ants to forage faster without sacrificing accuracy (chapter 5). Home range markings also interact with other information sources to affect ant behaviour (chapter 6). Trail pheromones assist experienced ants when facing complex, difficult-to-learn routes (chapter 7). When facing complicated routes, ants deposit more pheromone to assist in navigation and learning (chapter 7). Deposition of trail pheromones is suppressed by ants leaving a marked path (chapter 5), strong pheromone trails (chapter 7) and trail crowding (chapter 8). Colony level ‘decisions' can be driven by factors other than trail pheromones, such as overcrowding at a food source (chapter 9). Chapter 10 reviews the many roles of trail pheromones in ants. Chapters 11 – 14 focus on the organisation of cooperative food retrieval. Pheidole oxyops workers arrange themselves non-randomly around items to increase transport speeds (chapter 11). Groups of ants will rotate food items to reduce drag (chapter 12). Chapters 13 and 14 encompass the ecology of cooperative transport, and how it has shaped trail pheromone recruitment in P. oxyops and Paratrechina longicornis. Lastly, chapter 15 provide a comprehensive review of cooperative transport in ants and elsewhere.

Land-use and land cover changes impact the distribution of landscape features in rangelands and wildlife use of the landscape. To balance the requirements of wildlife groups that respond differently to landscape features, managers need more information on how these species use rangelands. Here, we investigate bat use of rangelands. We investigated the associations between bat activity and landscape features using acoustic monitoring and generalized linear mixed effect models. Trees and open water were positively associated with bat activity. We also investigated bat use of rangeland tree patches using a hierarchical modelling framework to build generalized linear models that included landscape, patch, and local level variables. Bats selected contiguous patches with low basal area. These studies show the importance of riparian forests for rangeland bats, and guide management of these areas. This data will aid managers in conserving rangeland bats and balancing their habitat requirements with those of other rangeland wildlife.
United States Forest Service; Prairie Biotic Research Inc.; The Nature Conservancy; North Dakota State University Agricultural Experiment Station

This thesis is focused on the analysis of eurasian beavers foraging behaviour and their strategy of getting food in the long-term perspective. First part (theoretical) of the thesis contains an explanation of the theory of the central place foraging, animal selective behaviour when food is selected and central place foraging influence on trees fertility. In this part is also mentioned the predation risk or how does the beaver perceives competitive pressure from other animals, and factors that can cause the change in population density of beaver colonies. The objective of this work is to determine the effect of long-term beaver populating on the volume of comsumed biomass and expanse of the territory, and a comparison of these results with one another in terms of different times of occupated territories. The second part describes the methodical procedure of the field survey. Data I collected from the areas of Šumava, Český les and South Moravia. I tried to find out, how the beaver´s foraging behaviour is induced depending on time inhabiting the territory and on increasing distance from the shore. This research shows that the beaver trips for food increases with age of occupation in 7-10 years and then the distance of tree cuts declined again from the shore. The volume of consumed biomass in reliance of increasing time of beaver occupation also decline and the most favoured tree species was an oak tree for which beavers were willing to walk long distances. The results of the simple analysis are presented as a measurement for both the entire region and also for each territory.

Master of Science
Department of Entomology
David C. Margolies
James R. Nechols
Many crops grown in greenhouses are damaged by the twospotted spider mite, Tetranychus urticae. The predatory mite, Phytoseiulus persimilis, is a commercially-available predator that is commonly used to control twospotted spider mites on greenhouse crops; but its efficacy varies among crops, and it is generally ineffective at low prey densities. In general, predator foraging efficiency depends on how well predators find prey patches, the length of stay in prey patches, and consumption of prey while in prey patches. With respect to P. persimilis, I asked how this predator responds to different prey distributions, as might be encountered at different stages of spider mite infestations. I also asked how components of foraging, namely consumption rate and dispersal tendency, affected predator efficiency. To examine the former, I established T. urticae eggs on 6-leafed cucumber plants in two distributions. To examine the latter, I imposed artificial selection on a population of P. persimilis to create a line that exhibited extremely high consumption and one that demonstrated a greater tendency for dispersal. Subsequently, foraging efficiency was assessed by observing predator oviposition and consumption of twospotted mite eggs on individual leaves of 6-leafed cucumber plants. The number of eggs laid by predators corresponded to the number of prey consumed regardless of predator line. In addition, predators from both lines distributed their eggs proportional to where they fed. However, prey consumption differed between selected lines in response to prey distribution. Predators selected for high consumption fed more on the basal leaf where they were released; whereas prey consumption by the high dispersal and control lines were more evenly distributed throughout the plant. These results contribute to a better understanding of how foraging behavior is modified in plant landscapes under different levels of expression of foraging traits. They also indicate that predator release strategies likely would need to modified in accordance with the kind of foraging trait(s) used in artificial selection programs. In general, my research, when combined with future studies at a broader landscape level, will facilitate decisions by biological control practitioners about whether changes in foraging efficiency resulting from artificial selection justify the cost investment of producing selected lines of P. persimilis

Food production and food consumption have been shown to have a great impact on our ecosystem. Human beings have been exploiting the planet in order to feed themselves. This will have negative consequences for future life on the planet. Modern food production and consumption are among the main causes of natural resource exploitation and the problem is very likely to increase. Indeed, during the past thirty years, the global population has grown exponentially by almost one billion every decade, and it is still growing at the same pace. This demographic explosion means that dramatic shifts in the production and consumption of food will be required. Working with food is a great chance to achieve or at least lead towards a condition of recovering, understanding the world around us and managing our natural resourcesÅ. Increasing control and efficiency in food production and consumption cannot solve the problem. There is a much broader spectrum of causes contributing to the ecological decline. It is necessary to look beyond the technological and economic aspects. It is, therefore, necessary to focus on cultural and behavioural causes, promoting the involvement of local peopleÇ. With this in mind, this research explores the potential of urban foraging for generating social consciousness about ecological sustainability using design as method of intervention, and involving food consumers in the process of production and consumption of food in a more sustainable way. In order to do that, this research focuses on a small scale urban foraging project. In this case, by food, I refer to spontaneous food that grow in the natural urban environment of Växjö, and that can be used as a resource for citizens. In summary, this research aims to promote the involvement of local people and to support knowledge exchange in order to pursue socio-ecological sustainability. Engaging with more participants, the research gains the capacity of addressing complexity in a more coherent manner, and use its outcome as a usable resource for the local community that aims to promote its self-sustenance.

The ability to invent new solutions to old or novel problems is often equated with intelligence, both in humans and non-human animals. Behavioural flexibility can be defined operationally by looking at the frequency of novel or unusual behaviours, i.e. innovations, in different taxa. Despite the potential survival benefits of behavioural flexibility in the face of changing conditions, there is variation among taxa in the propensity to innovate. Here, I examine in detail one foraging innovation, dunking behaviour (the immersion of food items in water) in Carib grackles (Quiscalus lugubris) of Barbados. I show that the rarity of dunking behaviour in the field is not due to the inability of most individuals to learn and/or perform it, but rather to the balance of costs and benefits not being favourable to its expression in most field conditions. In this population, dunking functions as a proto-tool food-processing technique speeding the ingestion of items that are difficult to swallow. The frequency of the behaviour depends on food characteristics, travel costs between the food source and water, and the probability of losing items to conspecifics. Dunking renders grackles vulnerable to food theft because it involves releasing food items in water, where there is often a build-up of conspecifics. When faced with a high risk of kleptoparasitism, grackles reduce the frequency of dunking, engage in aggressive displays, and keep items in the bill while dunking. Kleptoparasitism not only reduces the rate of dunking by increasing costs to the behaviour, but also by constituting an alternative foraging tactic. The payoffs to this tactic are frequency-dependent; i.e. they decrease as the frequency of kleptoparasites increases in the group. A comparative study on ecological, morphological and behavioural predictors of the occurrence of kleptoparasitic tactics among bird families point to an important role of predation and cognitive abilities in favouring the evolution of kleptoparasitism. Thus, avian food-stealing should not be regarded as a "cognitively simpler" alternative to intelligent behaviour, but as another form of behavioural flexibility. Large-brained primates and birds share the ability to learn quickly, innovate, use tools and engage in exploitative tactics, suggesting that these abilities have not been traded-off against each other, but have instead evolved together.

Pollinating insects exhibit a complex behavior while foraging for nectar and pollen. Many studies have focused on ultimate mechanisms of this behavior, however, the sensory-perceptual processes that constrain such behavior have rarely been considered. In the present study I used bumblebees (Bombus terrestris), an important pollinating insect, to investigate possible sensory constraints on foraging behavior. Additionally, I survey inter-individual variation in the sensory capabilities and behavior of bumblebees caused by the pronounced size polymorphism among members of a single colony. In the first chapter I have focused on the sensory-perceptual processes that constrain the search for flowers. I measured search time for artificial flowers of various sizes and colors, a key variable defining the value of a prey type in optimal foraging theory. When flowers were large, search times correlate well with the color contrast of the targets with their green foliage-type background, as predicted by a model of color opponent coding using inputs from the bee's UV, blue, and green receptors. Targets which made poor color contrast with their backdrop, such as white, UV-reflecting ones, or red flowers, take longest to detect, even though brightness contrast with the background is pronounced. When searching for small targets, bumblebees change their strategy in several ways. They fly significantly slower and closer to the ground, so increasing the minimum detectable area subtended by an object on the ground. In addition they use a different neuronal channel for flower detection: instead of color contrast, they now employ only the green receptor signal for detection. I related these findings to temporal and spatial limitations of different neuronal channels involved in stimulus detection and recognition. Bumblebees do not only possess species-specific sensory capacities but they also exhibit inter-individual differences due to size. Therefore, in the next two chapters I have examined size-related effects on the visual and olfactory system of Bombus terrestris. Chapter two deals with the effect of scaling on eye architecture and spatial resolving power of workers. Foraging efficiency in bees is strongly affected by proficiency of detecting flowers. Both floral display size and bee spatial vision limit flower detection. In chapter one I have shown that search times for flowers strongly increases with decreasing floral display size. The second factor, bee spatial vision, is mainly limited by two properties of compound eyes: (a) the interommatidial angle Çå and (b) the ommatidial acceptance angle Çá. When a pollinator strives to increase the resolving power of its eyes, it is forced to increase both features simultaneously. Bumblebees show a large variation in body size. I found that larger workers with larger eyes possess more ommatidia and larger facet diameters. Large workers with twice the size of small workers (thorax width) have about 50 per cent more ommatidia, and a 1.5 fold enlarged facet diameter. In a behavioral test, large and small workers were trained to detect the presence of a colored stimulus in a Y-maze apparatus. The stimulus was associated with a sucrose reward and was presented in one arm, the other arm contained neither stimulus nor reward. The minimum visual angle a bee is able to detect was estimated by testing the bee at different stimuli sizes subtending angles between 30° and 3° on the bee’s eye. Minimum visual detection angles range from 3.4° to 7.0° among tested workers. Larger bumblebees are able to detect objects subtending smaller visual angles, i.e. they are able to detect smaller objects than their small conspecifics. Thus morphological and behavioral findings indicate an improved visual system in larger bees. Beside vision, olfaction is the most important sensory modality while foraging in bees. Bumblebees utilize species-specific odors for detecting and identifying nectar and pollen rich flowers. In chapter three I have investigated the olfactory system of Bombus terrestris and the effect of scaling on antennal olfactory sensilla and the first olfactory neuropil in the bumblebee brain, the antennal lobes. I found that the pronounced size polymorphism exhibited by bumblebees also effects their olfactory system. Sensilla number (I measured the most common olfactory sensilla type, s. placodea), sensilla density, volume of antennal lobe neuropil and volume of single identified glomeruli correlate significantly with worker’s size. The enlarged volume of the first olfactory neuropil in large individuals is caused by an increase in glomeruli volume and coarse neuropil volume. Additionally, beside an overall increase of brain volume with scaling I found that the olfactory neuropil increases disproportionately compared to a higher order neuropil, the central body. The data predict a higher odor sensitivity in larger bumblebee workers. In the last chapter I have addressed the question if scaling alters foraging behavior and rate in freely foraging bumblebees. I observed two freely foraging B. terrestris colonies and measured i) trip number, ii) trip time, iii) proportion of nectar trips, and iv) nectar foraging rate of different sized foragers. In all observation periods large foragers exhibit a significantly higher foraging rate than small foragers. None of the other three foraging parameters is affected by workers’ size. Thus, large foragers contribute disproportionately more to the current nectar influx of their colony. To summarize, this study shows that understanding the mechanisms of visual information processing and additionally comprising inter-individual differences of sensory capabilities is crucial to interpret foraging behavior of bees
Blüten bestäubende Insekten zeigen während ihrer Suche nach Nektar und Pollen ein komplexes Sammelverhalten. Bisher wurde eine Vielzahl von Studien durchgeführt um die ultimaten Mechanismen dieses Verhaltens aufzuklären; jedoch die diesem Verhalten zugrundeliegenden sensorischen Leistungen und Limitierungen wurden dabei nur selten berücksichtigt. In der vorliegenden Arbeit habe ich das Sammelverhalten von Hummeln (Bombus terrestris) und potentielle, das Verhalten limitierende sensorischen Zwänge untersucht. Zusätzlich konnte ich Unterschiede im sensorischen System individueller Hummeln aufdecken, die durch den ausgeprägten Größenpolymorphismus dieser Tiere verursacht werden. Im ersten Kapitel habe ich die visuellen Prozesse, die die Suche nach Blüten limitieren betrachtet. Hierfür habe ich die Suchzeiten von Hummeln für künstliche Blüten verschiedener Größe und Farbe in einer Flugarena bestimmt. Bei großen Blüten korrelieren die gemessenen Suchzeiten mit dem Farbkontrast zwischen der Blüte und dem blatt-grünen Hintergrund. Bei Blüten mit geringem Farbkontrast benötigen die Tiere am längsten um sie zu detektieren, obwohl die Blüten einen starken Helligkeitskontrast aufweisen. Diese Ergebnisse stimmen mit den Vorhersagen eines Farbseh-Modells überein, das die Information von den UV-, Blau- und Grünrezeptoren der Hummel verrechnet. Bei der Suche nach kleinen Blüten allerdings ändern die Hummeln ihre Strategie. Sie fliegen jetzt signifikant langsamer und näher am Untergrund um dadurch die Wahrscheinlichkeit zu erhöhen, die Blüten zu detektieren. Zusätzlich benutzen die Hummeln einen anderen neuronalen Kanal für die Blütenerkennung: anstatt des Farbkontrastes nutzen sie jetzt nur noch die Informationen des Grünrezeptors, d.h. den Kontrast zwischen Blüte und Hintergrund, der durch den Grünrezeptor wahrgenommen wird. Ich konnte zeigen, dass der Wechsel zwischen den beiden neuronalen Kanälen durch zeitliche und räumliche Eigenschaften dieser Kanäle verursacht wird. Die sensorischen Leistungen einer Hummel sind nicht nur durch ihre Artzugehörigkeit festgelegt, sondern weisen beträchtliche Unterschiede zwischen großen und kleinen Tieren auf. In den nächsten zwei Kapiteln habe ich deshalb Größeneffekte auf das visuelle und olfaktorische System von Bombus terrestris untersucht. Im zweiten Kapitel beschäftige ich mich mit den Auswirkungen des Größenpolymorphismus auf die Augenmorphologie und das räumliche Auflösungsvermögen von Hummelarbeiterinnen. Das räumliche Auflösungsvermögen des Hummelauges wird hauptsächlich von zwei Faktoren bestimmt: (a) dem Divergenzwinkel zwischen zwei Ommatidienachsen Çå, und (b) dem Öffnungswinkel eines Ommatidiums Çá. Beide Faktoren sind von der Zahl und dem Durchmesser der vorhandenen Ommatidien in einem Komplexauge beeinflußt. Ich konnte nachweisen, daß sich große und kleine Hummeln stark in der Zahl und dem Durchmesser ihrer Ommatidien unterscheiden. Große Hummeln mit der doppelten Thoraxbreite im Vergleich zu ihren kleinen Nestgenossinnen weisen 50 Prozent mehr Ommatidien und einen 1.5-fachen Linsendurchmesser auf. In einem Verhaltensversuch habe ich den kleinsten Sehwinkel, mit dem ein farbiges Objekt von einer Hummel noch erkannt werden kann bestimmt. Auch hier zeigte sich ein starker Größeneffekt. Um so größer die Hummel ist, um so kleiner ist der Sehwinkel unter dem sie ein Objekt gerade noch wahrnehmen kann. Sowohl morphologische Daten als auch Verhaltensdaten zeigen deutlich, dass größere Hummeln ein besseres visuelles System besitzen. Neben dem Sehen ist der Duft die wichtigste sensorische Modalität, die Hummeln während des Sammelns nutzen. Im nächsten Kapitel habe ich mich daher mit möglichen Größeneffekten auf das olfaktorische System beschäftigt. Ich konnte zeigen, daß die Zahl der wichtigsten olfaktorischen Sensillen auf der Antenne, Sensilla placodea, mit zunehmender Körpergröße ansteigt. Das erste olfaktorische Neuropil im Gehirn, die Antennalloben, skalieren ebenfalls mit der Körpergröße. Die Volumenzunahme des Neuropils ist auf eine Volumenzunahme der einzelnen Glomeruli und der Zahl der Interneurone zurückzuführen. Außerdem konnte ich nachweisen, daß das Volumen des olfaktorische Neuropils im Vergleich zu zentralen Hirnregionen überproportional zunimmt. Die Ergebnisse lassen eine höhere Sensitivität des olfaktorischen Systems bei großen Hummeln erwarten. Im letzten Kapitel habe ich mögliche Auswirkung der Körpergröße auf das Sammelverhalten von Hummeln unter natürlichen Bedingungen untersucht. Ein überlegenes visuelles und olfaktorisches System bei größeren Hummeln läßt eine bessere Blütenerkennung, und damit auch eine höhere Sammeleffizienz vermuten. Hierfür habe ich Nektarsammelraten von verschieden großen Tieren im Freiland bestimmt. Größere Tiere zeigen dabei eine höhere Sammelrate (Nektareintrag pro Zeit) im Vergleich zu ihren kleineren Nestgenossinnen. Größere Tiere tragen damit überproportional zum täglichen Nektarinflux einer Kolonie bei. Die Ergebnisse dieser Arbeit zeigen deutlich, dass das Sammelverhalten bei Blüten besuchenden Insekten nur dann richtig verstanden und interpretiert werden kann, wenn man die dem Sammeln zugrundeliegenden sensorischen Prozesse und mögliche individuelle Modifikationen kennt und mit einbezieht

Knowing how species will respond to environmental variability and climate change requires understanding the factors that influence their distribution and movement patterns. I investigated the processes that drive individuals to concentrate in specific areas of their home range by modeling encounter rates of humpback whales (Megaptera novaeangliae) in relation to environmental variables using GIS tools, generalized additive models, and remote sensing and in situ data. I conducted this work at two foraging areas: the coastal waters of British Columbia, Canada, and the Bransfield and Gerlache Straits, Antarctica. Humpback whales in British Columbia were strongly associated with latitude and bathymetric features. The relationships with remotely sensed variables reflecting primary productivity were not consistent, but higher numbers of whales seemed to be associated with higher productivity. In fact, the highest concentrations of humpback whales appeared to reflect areas where concentration and retention processes lead to higher biological productivity, including south Dixon Entrance, middle and southwestern Hecate Strait and off Juan de Fuca Strait. Humpback whales in the Southern Ocean also preferred areas of enhanced biological productivity. In Gerlache Strait, humpback whales were associated with areas of higher chlorophyll-a concentration in the central and northern sections of the strait, which also corresponded to relatively higher temperatures and shallower mixed layer depths for the in situ data. In Bransfield Strait, humpback whales appeared to prefer the near-frontal zones and the deep basins, where surface waters are influenced by the Bransfield Current. Interannual variability in both humpback and minke whale encounter rates in Gerlache Strait was correlated with the Oceanic Niño Index, the oceanic component of ENSO. In addition to investigating species-habitat relationships with statistical models, I conducted the first study to describe the satellite-monitored movements of humpback whales on their feeding grounds along the Antarctic Peninsula. Results showed considerable individual variation in direction, speed and range of movements, and an overall pattern characterized by short- and long-distance movements between presumed foraging areas with relatively short residency times. All told, the results of my research show that humpback whale distribution within foraging habitat is influenced by physical and biological variables that enhance biological productivity.

Movements of animals form a vital link between individual behaviour and spatial processes affecting populations, communities and ecosystems. Predators often have to search for prey that is unpredictable or patchily distributed and increasingly have to do so in habitats that are changing as a result of climate change or anthropogenic activity. Our understanding of animal movement has been revolutionised by the development of miniaturised loggers which allow tracking of individual animals over a range of spatial and temporal scales. However, while flight heights of birds are a critical component of avian movement ecology, they have been little-studied in comparison to horizontal movements. In this thesis I examine the three-dimensional foraging behaviour of northern gannets (Morus bassanus) at the world's largest breeding colony, at Bass Rock, Scotland. I first combine GPS and pressure data to estimate flight heights, and develop a novel refinement that uses sea surface pressure data to correct estimated heights during long periods of sustained flight. I then investigate sexual differences and effects of weather on three-dimensional foraging behaviour, before examining potential population-level consequences of mortality from collisions with offshore wind turbines. I found that sexual differences in foraging behaviour extend to the heights at which birds fly, and that wind speed in particular has a marked effect on movements and behaviour at sea. I also found that predicted levels of mortality from offshore wind farms would be likely to retard population growth but unlikely to drive the population into long-term decline. My thesis describes some of the complexity and flexibility of gannet foraging behaviour and highlights the importance of understanding movements in three dimensions.

The consequences of predation have become a central focus of marine ecological research. Numerous studies have emphasized the importance of apex predators in structuring assemblages at various organisational levels and in determining how ecosystems function. However, less appreciated currently is the fact that predators display multiple foraging behaviours, thereby allowing them to overcome problems associated with unpredictability of food resources in space and time. The primary goal of this dissertation is to contribute to growing understanding of the ecological causes and consequences of foraging plasticity displayed by Greater Flamingo Phoenicopterus ruber roseus in intertidal sandflat ecosystems in Langebaan Lagoon, South Africa. P. roseus feeds by either (1) creating pits, which involves flamingos stirring up deep sediments with their feet or (2) creating channels, in which their inverted bills are swept from side-to-side on the sediment surface. The first objective of the study was to quantify the ecological drivers of decisions made by flamingos to feed, and to implement either pit- or channel-foraging strategies. The latter was achieved through RandomForest modelling techniques that identified the prominent ecological drivers from a suite of biotic and abiotic variables. Results indicate that biotic variables, i.e. those associated with flamingo prey assemblages, were key in driving choices made by flamingos to forage and to implement either pit- or channel-foraging strategies. The second aim of this dissertation was to quantify the repercussions of the two different foraging behaviours on benthic assemblages. Comparisons of benthic assemblages in flamingo foraging structures (pits and channels) with adjacent non-foraged sediments (controls) indicated differential effects of both flamingo foraging methods on benthic communities, with channel-foraging eliciting a greater negative impact compared to pit-foraging, for which impacts were negligible. Abundance of macrofauna and surface-dwelling taxa such as micro-algae and the amphipod Urothoe grimaldii were all negatively impacted by channel-foraging. Sizes of channels constructed by flamingos were inversely related to their impacts, with impacts on macrofaunal abundance being greater in smaller channels. Overall, this study has shed light on the differential effects of foraging plasticity on prey assemblages and its importance in enhancing spatio-temporal heterogeneity in intertidal sandflats. The study also emphasizes the need to incorporate foraging plasticity into current thinking and conceptual models of predation in marine soft sediments, in order to appreciate the full spectrum of predation effects on assemblages.

Social foraging behaviour has an important influence on individuals’ survival and reproduction through its role in the acquisition of food resources. It also determines the amount of foraging time required in differing environments, and so the amount of time available for other activities, such as socialising and resting, which have been implicated in an individual’s fitness, as well as the stability of the wider social group. In this thesis I explore the links between these two processes by investigating the drivers of social foraging behaviour, and how the foraging time budgets that this behaviour produces vary between environments. I do this using data collected from a wild population of chacma baboons (Papio ursinus) in Namibia, under both natural and field-experimental conditions, and through the development of an individual-based model (IBM). I show that baboon foraging decisions are influenced by social and non-social factors, but that the relative influence of these factors is dependent on the characteristics of the forager and the habitat it is in. These differences in decision-making appear to allow all individuals in a group to experience similar foraging success under natural conditions, but this pattern breaks down in extreme conditions. Using these findings to build an IBM of social foraging, I show that the time individuals need to spend foraging can increase rapidly in a deteriorating environment to the point where they are no longer able to gather enough resources. Overall, the findings of this thesis contribute to the growing appreciation that social foragers can exhibit a high degree of behavioural flexibility. These findings also emphasise the long-standing recognition that individual-level behaviours have an important influence on higher-level ecological patterns and processes and that an appreciation of this is important, not only for our understanding of these patterns and processes, but also for informing conservation and management.

This thesis investigates nesting success, foraging behaviour, chick diet and growth of three ecologically contrasting species (skylark Alauda arvensis, yellowhammer Emberiza citrinella and song thrush Turdus philomelos) on farmland, in relation to microhabitat and the availability of invertebrates. Fieldwork was conducted on a lowland mixed arable farm in Leicestershire over the breeding seasons 2000 - 2002. Telemetry was used to monitor adult song thrushes and fledgling skylarks. Skylark nest density was highest in set-aside and lowest in crops, yellowhammer nest density was greatest in herbaceous vegetation and field margins whilst song thrush nest density was greatest in hedgerows and woodland. Birds did not utilise the available habitat at random for nesting. Provisioning skylarks and yellowhammers utilised managed set-aside strips more than would be expected, although both foraged in cereals. Song thrushes foraged primarily in woodland and boundary habitats, avoiding cereal crops, permanent pasture and set-aside. The largest cause of nest failure for each study species was predation. Skylark nest survival improved with increasing vegetation density at the nest site. Yellowhammer nest survival was affected by temperature and rainfall. Song thrush nest survival was affected by predator control, nest site location on the farm and habitat. Skylarks selected sparse vegetation and bare ground when foraging in winter cereals. Each species selected some invertebrate taxa over others, independently of chick age. Skylarks and yellowhammers did not forage in sites with greater invertebrate abundance than others, but song thrushes tended to forage in habitats with higher invertebrate biomass. Skylark chick growth rates were positively influenced by set-aside and negatively by spiders in the diet and the proportion of 'other habitats' around the nest. Skylark chicks with higher growth rates were more likely to fledge. No habitat effects or environmental factors were found to affect song thrush chick growth rates. Tagged skylark chicks exhibited a low post-fledgling survival rate, with most predated whilst flightless. This thesis identified actual and potential conservation benefits for nationally declining skylark, yellowhammer and song thrush populations arising from the management of cropped and non-cropped habitats.

This is a study of the foraging behaviour of Carcinus maenas on Mytilus edulis and of Thalamita danae on Perna viridis. Particular attention is given to differences arising in foraging behaviour as a result of intraspecific prey heterogeneity and experimental protocol. Intersite and temporal differences in the population density, shell morphology, biomass and byssal attachment strength of Mytilus edulis were found. Byssal attachment strength and shell strength were highly variable amongst individuals of a similar size. Carcinus maenas is strongly heterochelous. Intraspecific differences in the chelal mechanics, but not in the chelal geometry, were recorded; major chelae of large male crabs were significantly stronger than the major chelae of females and small males. Stomach content analyses showed that Carcinus maenas has a broad diet in which Mytilus edulis forms an important component. Intersite differences inMytilus edulis shell morphology altered the foraging behaviour of Carcinus maenas, and intersite and temporal variations in mussel flesh weight altered the prey value curves. Both C. maenas and Thalamita danae were highly prey size-selective when foraging on groups of different sized mussels, the size of prey most vulnerable to predation altering with the size composition of the group. The handling times of mussels for both species of crab were reduced when mussels were presented as part of a group as compared to when mussels were presented singly. For Carcinus maenas the reduced handling times resulted from the less extensive gleaning of mussel shells whilst for Thalamita danae reduced handling times appeared to result from the greater use of a more time efficient opening technique. When Carcinus maenas were presented with mussels of differing attachment strengths, crabs selected more weakly attached mussels over those with a more firm and rigid attachment. This selection did not appear to be based on prey value or prey length but rather on the resulting slight movement of weakly attached mussels whenever these were touched by a foraging crab.

Lo scopo principale dei motori di ricerca, che supportano il compito di information retrieval, è quello di fornire agli utenti un metodo facile per trovare informazioni sul Web. Nonostante i loro vantaggi, i motori di ricerca hanno ancora numerosi limiti. Sono state realizzate diverse opere per migliorare i sistemi di accesso alle informazioni e offrire un'esperienza di utilizzo migliore in settori diversi, come distribuite e contestuali information retrieval, link analysis e exploratory search. Questa tesi si occupa di Web Information Foraging, un paradigma di information access più recente che mira a scoprire i percorsi che portano a informazioni rilevanti sul Web. L'obiettivo principale della ricerca intrapresa durante il Ph.D. è stato quello di progettare e implementare sistemi efficaci ed efficienti di Information Foraging basati sulla tecnologia multi-agent. A questo scopo, abbiamo studiato information foraging in diversi domini, tra cui salute, pubblicazioni scientifiche e social media. Per affrontare questo problema, abbiamo proposto un'architettura modulare con due fasi importanti per il sistema di Information Foraging. La prima fase è un processo di apprendimento che mira a localizzare le pagine Web più rilevanti che potrebbero interessare l'utente secondo i propri interessi. Questo può essere eseguito su un'istanza fissa del Web. La seconda fase tiene conto dell'apertura e della dinamicità del Web e consiste in un apprendimento incrementale partendo dai risultati della prima fase e ricondizionando i risultati tenendo conto delle modifiche apportate sul Web. L'intero sistema offre uno strumento per aiutare gli utenti a accedere facilmente alle informazioni online. Lo sviluppo del sistema ha attraversato tre importanti passaggi in cui sono stati utilizzati diversi concetti e tecnologie per ottenere efficacia ed efficienza e anche rendere il sistema in grado di operare in diversi ambienti. Innanzitutto, abbiamo proposto un approccio basato sulla Swarm Intelligence per simulare il processo di foraggicazione come descritto nella Information Foraging Theory. Abbiamo eseguito la nostra proposta utilizzando Bee Swarm Optimization (BSO) per realizzare un processo automatico di information foraging fondato sul comportamento del foraggicazione delle informazioni dell'uomo. Conoscendo che BSO è un approccio di swarm intelligence che coinvolge agenti reattivi e che il concetto di Information Foraging si basa sulla natura, abbiamo pensato che questo potrebbe essere uno dei modi più appropriati per affrontare il problema del Web Information Foraging. Per convalidare la nostra proposta, sono stati condotti esperimenti su MedlinePlus, un sito dedicato al dominio medico e che contiene informazioni su oltre 1000 malattie e condizioni sanitarie. I risultati sono stati promettenti e hanno dimostrato la capacità di Information Foraging di accedere alle informazioni pertinenti sul Web in base agli interessi di un utente.
The main purpose of search engines, which support the task of Information Retrieval, is to provide the users with an easy method to find information on the Web. Despite their advantages, Web search engines still have numerous limitations. Several works have been done to enhance information access systems and offer a better user experience in different fields such as distributed and contextual information retrieval, link analysis and exploratory search. This thesis deals with Web Information Foraging, which is a recent information access paradigm that aims at discovering paths leading to relevant information on the Web. The principal goal of the research undertaken during the Ph.D. has been to design and implement effective and efficient Information Foraging systems based on multi-agent technology. For this purpose, we investigated Information Foraging in different domains including health, scientific publications and social media. To address this issue, we proposed a modular architecture with two important phases for the Information Foraging system to be developed. The first phase is a learning process, which aims to locate the most relevant Web pages that might interest the user according to his/her interests. This can be performed on a fixed instance of the Web. The second phase takes into account the openness and dynamicity of the Web and it consists of an incremental learning starting from the results of the first phase and reshaping the outcomes taking into account the changes that occur on the Web. The whole system offers a tool to help users access information online easily. The development of the system went through three important steps, where different concepts and technologies were used in order to achieve both effectiveness and efficiency and also to make the system able to operate on various environments.

The current study utilized two experiments to assess Smith's (1981) simple per capita-maximization model, which provides a quantitative framework for predicting optimal group sizes in social foraging contexts. Participants engaged in a social foraging task where they chose to forage for points exchangeable for lottery prizes either alone or in a group that has agreed to pool and share all resources equally. In Experiment 1, groups (“settlements”) of 10 or 12 participants made repeated group membership choices. Settlements were exposed to three conditions in which the optimal group size was either 2, 5, or 2 for the 10 person settlement or 3, 4, or 6 for the 12 person settlement. A linear regression of the data from Experiment 1 revealed a strong relationship between the observed group sizes and group sizes predicted by the simple per capita maximization model. Experiment 2 was a systematic replication of Experiment 1 in which single participants foraged for shared resources with groups of automated players in a computerized simulation. Automated player group choices mirrored group choices of participants in Experiment 1; excluding the data for the best performing participant. Thus, the participant acted essentially in the stead of the best performing participant for each condition. Two logistic regressions provided mixed support for the model, while failing to replicate the results of Experiment 1, providing mixed support for the use of the simple per capita maximization model in predicting group sizes in social foraging contexts.

Although deer abundance is high throughout most areas of Virginia, parts of western Virginia, especially on public lands, have comparatively low density deer populations. Concerns voiced by sportsmen regarding declining deer numbers in this region prompted interest in research to investigate the role of predation on deer populations. The coyote (Canis latrans) is a relative newcomer to Virginia, and relatively little is known about the role coyotes play in Virginia ecosystem dynamics, including their interactions with other sympatric predators. Research studies in other areas suggest that predation from coyotes, bobcats (Lynx rufus), and black bears (Ursus americanus) may be a significant source of deer (Odocoileus virginianus) mortality, especially for fawns, and the cumulative effects of predation from these sources may also increase the potential for additive mortality in deer populations. An important consideration when comparing feeding strategies of carnivores is the relative availability of food items across the landscape. I estimated the relative seasonal availability of several potential food items in a mosaic landscape that included some areas of prescribed burning and variable timber harvest in the mountains of western Virginia between June 2011 and May 2013. I focused on 4 broad categories of food items: white-tailed deer, mid-sized mammals (raccoons, Procyon lotor, opossums, Didelphis virginiana, cottontails, Sylvilagus spp., and squirrels, Sciurus spp.), small mammals, and soft mast. I used distance sampling to estimate deer density, camera trapping techniques to estimate mid-sized mammal trapping rates and occupancy, mark-recapture techniques to estimate small mammal abundance, and vegetation sampling to estimate % cover, which I used as measures of food availability for predation. To estimate carnivore diet, I analyzed scats of coyotes (n = 334), bobcats (n = 258), and black bears (n = 107) collected monthly from June 2011 and May 2013. Additionally, I compared estimates of % occurrence to estimates of seasonal availability of deer, mid-sized mammals, small mammals, and soft mast by ranking availability of food items from 0 (unavailable) to 4 (highly available) from my monthly and seasonal food item abundance and density estimates. I then ranked % occurrence in scat on a 0 - 4 scale and compared diet rankings to food item availability where changes in rank indicate differences from the generalist diet.

Deer densities were substantially higher in Bath County (4.75 - 16.06 deer/km2) than in Rockingham County (0.17 - 3.55 deer/km2). I estimated availability of other food items only in Bath County. For mid-sized mammals, I estimated low activity as shown by constant, but low, trapping rates (#photo events/trap nights*100) of opossums, and relatively higher, constant trapping rates of cottontails. Raccoon and squirrel trapping rates were highly variable across seasons and raccoon occupancy (proportion of sites occupied) was higher in summer and fall (0.51 - 0.59) whereas squirrel occupancy was highest in October-November (0.51 - 0.53). Cottontail and opossum occupancies were higher in burned areas (0.40 - 0.57, 0.24 - 0.46, respectively), whereas raccoon and gray squirrel occupancies were higher in unburned areas (0.23 - 0.78, 0.12 - 0.58, respectively). Using program MARK I estimated high abundance and density of Peromyscus spp. in all seasons relative to other small mammal species. Densities of meadow voles and jumping mice were high seasonally in open field habitat. Densities of eastern chipmunks, red-backed voles, and Peromyscus spp. were significantly higher in burned areas relative to unburned sites. Among soft mast species, blueberries comprised the largest % occurrence. I expect a generalist predator to consume deer at a constant rate and have lower % deer occurrence in Rockingham County where deer densities are much lower. I expect seasonally constant, but low, occurrence of opossum and relatively higher, but similarly constant, occurrence of cottontail. I expect raccoon occurrence to be relatively high in summer and fall, and lower in winter. Squirrel occurrence should peak in October and November, followed by a steady decline until June. Based on availability, Peromyscus spp. should be the most commonly occurring small mammal in the diet of a generalist predator, rivaled by meadow voles (Clethrionomys gapperi) in fall and perhaps summer. I expect chipmunks (Tamias striatus) and red-backed voles to occur at constant but low rates in predator diets. I predict that various species of soft mast may occur during their respective fruiting seasons.

Deer were the most frequently occurring food item of coyotes in all months in both counties, with % biomass consumed highest in June (Bath: 60.0 - 90.9 %; Rockingham: 55.6 - 92.3%). Deer occurrence in bobcat scat peaked in June (77.54 %). In black bear scat, deer occurrence was highest in February and March (100 %), however sample sizes in these months were extremely low (n = 2, 3 respectively). All 3 predators consumed deer more than expected in June and July. In most months, coyotes consumed deer and soft mast more often than expected (1 rank higher) and they consumed deer much higher (2-3 ranks higher) than expected in January and February. While deer was a major food item in the diets of all 3 predators, it is unclear whether this observed result was caused by predation or scavenging. It is unlikely that coyotes, bears, or bobcats are preying on adult deer with high frequency. I did not estimate the availability of deer carcasses for scavenging in this study. If deer carcasses are highly available in the study area, this may explain the high occurrence of deer in carnivore scat and the lack of seasonality in coyote samples.

Mice (Peromyscus spp.) were consumed by predators less than expected based on availability, whereas squirrels and chipmunks were consumed by bobcats more than expected. Meadow and red-backed voles were consumed more than expected by both bobcats and coyotes. Mid-sized mammals occurred with expected frequency or lower in predator scats. Coyotes had the lowest diversity and variation in diet, whereas bobcat and bear diets were more diverse including seasonal use of many species. Coyotes exhibited more selectivity (based on changes, and magnitude of changes, in rankings for food item occurrence versus availability) and appear more specialized on deer in all months than bobcats.

I analyzed 203 randomly-selected coyote fecal samples using a modified Wisconsin fecal flotation technique. I identified 13 parasite taxa, 9 of which occurred with adequate frequency to permit statistical analysis. No landscape patterns or statistically significant seasonal differences were found in prevalence of parasite taxa, and only A. caninum and Eimeria spp. were significantly higher, and Cystoisospora spp. was somewhat significantly higher, in Bath versus Rockingham Counties. By comparing my data on spatio-temporal patterns of food availability to patterns in the scats of predators, we have better understanding of predator foraging strategies and can identify opportunities for targeted management to balance predator-prey dynamics with human needs and values. More research is needed on the interactions of sympatric predators in specific areas to gain further inferences regarding population-level impacts of predation on deer in western Virginia.
Master of Science

Thesis (Ph.D.)--University of North Carolina Wilmington, 2008
Title from PDF title page (viewed May 26, 2009) Includes bibliograpical references (p. 80-83) Includes bibliographical references (p. 80-83)

The principal objective of the research project Wolverines in a Changing World was to gain better insights into the role wolverines have in ecosystem dynamics, their adaptation to ecosystem change, and its implications for sustainable management of the natural environment. The aim of this thesis, within these settings, was to investigate wolverine foraging strategies in a multiple-use landscape, especially in higher alpine habitat where livestock are grazed without human supervision or protection and in the boreal forest where wolverines co-exist with other intra-guild species. This aim was addressed by focusing on the following research questions.

1. Which analytical method is most appropriate to analyze wolverine diet? [Paper I]

2. Do wolverines shift their food habit in areas where they co-exist with wolves? [Paper II]

3. Which foraging strategies do wolverines employ within a predator guild? [Paper III]

4. Is the large carnivore guild differentiated in habitat tolerances and distribution, and what effect does this have on the potential for regional zoning of large carnivores? [Paper IV]

5. Can spatio-temporal variation in lamb depredation rates be explained by local wolverine density and/or predator removal programs, and are certain demographic classes of wolverines responsible for the increased depredation rate during the latter portion of the grazing season? [Paper V]