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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
461

Optimal foraging on the roof of the world: A field study of Himalayan langurs

Sayers, Kenneth A. 22 April 2008 (has links)
No description available.
462

The Foraging and Travel Patterns of White-Faced Sakis in Brownsberg Nature Park, Suriname: Preliminary Evidence for Goal-Directed Foraging Behavior

Anzelc, Avis M. 20 July 2009 (has links)
No description available.
463

Consumer as Inforagers: Ecological Information Foraging under Information Overload Paradigm - An Integrative Perspective between Darwinism and Non-Darwinism

Kim, Wooyang January 2014 (has links)
The main purpose of this dissertation is to assess ontological issues of information acquisition, focusing on information overload from an integrative perspective of two theoretical foundations, which links two perspectives of consumer behavior in information acquisition: foraging theory in behavioral ecology and information processing theory in marketing. Applying to the integrative investigation, the current research primarily emphasizes the infusion of ecological rationality (i.e., Darwinian Theory) into normative rationality (i.e., Newtonian Theory), but it is not alternative but complementary to each other. Ecological rationality, which is rooted in Darwinism, emphasizes that human behavior has developed through adaptation and natural selection as the human minds interact with environments. The current study consists of five chapters: the philosophical foundation of the rationalities, exploratory study, proposed hypotheses, empirical tests, and general discussion. A summary of the contents of each chapter is: The first chapter aims to provide an integrative framework of consumer information acquisition in order to explore ontological issues in information overload paradigm, attempting to synthesize different approaches in marketing and behavioral ecology. To explore, the current study emphasizes an integrative perspective between two theories for information acquisition (foraging and information processing), which are based on different philosophical foundations of the rationality (ecological and normative). Along with the process of the information acquisition, this study provides relevant consequences (decision-related responses and decision-related alternatives) after the information acquisition process and influential factors in temporal and psychological dimensions (time and motivation). Then, the conceptual study provides conclusion and the current research scope. The second chapter aims to examine the efficacy of the current study's theoretical integration in the process of consumer information foraging so as to approach an ontological issue in information overload paradigm: more information is better vs. less information is better (i.e., information processing theory and foraging theory under an information overload paradigm). Therefore, this study explores and examines what can be appropriate information structures to describe the ontological issue in the process of consumer information foraging. To formulate the adequate information structure, this study attempts to utilize an integrative perspective between marketing and behavioral ecology. This study examines consumers' online activities sequentially from a broad to detail approach, based on the categories of goods and services. The result, by and large, suggests a necessity of an integrative perspective to view a holistic information structure, including quantity, quality, and environment components. These structural components interactively communicate with minds when shaping the process of the consumer information foraging, which are likely to involve in the degree of information overload. Moreover, results demonstrate rather higher variation of strategic information foraging but emphasize some important communality in the initial stage of information foraging, such as the role of search engine and interpersonal communication. In addition, categories of goods and services affect shaping the pattern of strategic information foraging. Then, the conclusion of the study provides. The third chapter aims to propose a hypothetical model, based on the theoretical backgrounds in Chapter 1 and the findings of the exploratory study in Chapter 2. In addition, the pilot study was conducted to provide a concrete framework of the empirical study by checking the manipulation of holistic information structures. The manipulation of the structures includes the total quantity of information, the quality of information, and environmental information. Those structures measured on several resultant consequences, using the patch concepts (within-patch and between-patch). Controversially, in general, consumers tend to prefer more information rather than less information only when arranged information provides; otherwise, this preference attenuates. This controversial result also has conflicting variations, depending on the types of patches. Overall, the comparison in the within-patch and between-patch through displaying heterogeneous information structures suggests that holistic information structures are a more important factor than the mere quantity or quality of information. The fourth chapter empirically tests the theory-based hypothetical frameworks to assess the ontological issues in information overload paradigm using the integrative perspective of the two information acquisition theories. The findings of the empirical study suggest that the real-world information overload is not simply determined by a single dominant factor (e.g., quantity), but by the interplay of intricately intertwined factors. The factors are the following: information structures (three unarranged and four arranged information structures, including quantity, quality and environment), item categories (durables, nondurables and services), and time constraints (time pressure vs. no time pressure). The interwoven complexity implies that paradigmatic change of perspectives in relation with information overload though integrating two important conceptual factors between domain-specific dependency and universality. Moreover, the information overload begins with the browsing stage of acquiring the necessary information, not with the searching stage, suggesting the view of browsing-searching continuum that underscores the important role of the patch concept. As a whole, the conclusive findings suggest an integrative perspective between Darwinism and Non-Darwinism as a prerequisite of providing a better comprehension of the issues of the information overload paradigm. The fifth chapter is the section of general discussion including major findings, theoretical, methodological and empirical implications, limitations, and conclusive statement. / Business Administration/Marketing
464

Bat Resource Utilization Along the Potomac River Corridor in Maryland

Litterer, Amber Starr 15 April 2024 (has links)
In 2021, 17-year periodical cicadas (Magicicada spp.) in Brood X emerged throughout much of the eastern United States. Due to their abundance and lack of predator avoidance during their short six-week period on the above-ground landscape, many species of animals consume cicadas and in turn have short-term habitat use and population responses. The response of bats to periodical cicadas is largely unknown. Using a before-after-control-impact study design, we deployed ultrasonic acoustic detectors during the summers of 2020–2022 within and just outside the range of the cicada emergence along the Potomac River corridor of Maryland and Virginia. For total bat activity, there was significantly more acoustic activity within the range of the cicada emergence the year during and the year following emergence than where emergence did not occur. Additionally, for all individual species and phonic groups, bat activity increased the year during and year after the emergence within the range of periodical cicadas compared to the year prior to emergence. Our study demonstrates that periodical cicadas may serve as a resource pulse that can cause an increase in bat activity and suggests at least a short-term local to regional population increase from immigration the year during and from recruitment the year following. Bats of the mid-Atlantic have been negatively affected by numerous stressors including white-nose syndrome, wind turbine development, and land use change. One species suffering widespread population decline over the last decade in the mid-Atlantic has been the little brown bat (Myotis lucifugus). Understanding the space use and resource selection of remaining populations is critical for management and species recovery. Nevertheless, there are difficulties with studying the movement of insectivorous bats due to their small size and high vagility. Traditional foraging studies of Myotis spp. have used fixed station telemetry and associated multi-azimuthal observations to estimate the location of individuals. However, single azimuth observations are often unable to be included in these studies leading to more potential location estimates missing from movement models. During the summer of 2022, I radio-tagged little brown bats from a maternity colony along the Potomac River in Maryland and collected bearings on nine individuals using fixed station telemetry from sunset until bats returned to the maternity roost. Location estimates were obtained from both single and multi-azimuthal observations. I fit movement models for each individual and used auto-correlated kernel density estimation (AKDE) to estimate space use. I also assessed second and third order habitat selection of individual bats. The average 95% AKDE for males was 889 ha ± 424.6 and 699.3 ha ± 129 for adult females. I found bats had higher predicted use of habitat that was closer in distance to water and wetlands and further from open habitat at the second order and closer to water and open habitat at the third order of resource selection. Habitat associations were similar to previous little brown bat resource selection studies. However, estimates of space use were larger than those using other movement models. This study was novel in that it incorporated single azimuth observations and periodicity into models of space use, thereby increasing sample size and offering a new framework for future telemetry studies. These estimates of space use can be used by land managers to protect the habitat of this imperiled species. / Master of Science / In 2021, 17-year periodical cicadas (Magicicada spp.) in Brood X emerged throughout much of the eastern United States in high abundance. As an abundant food resource, many animals consume periodical cicadas while they are above ground during the summers. This has allowed for short-term population increases and changes in reproduction in some species. However, the response of bats to periodical cicadas is largely unknown. To study this, I deployed ultrasonic acoustic detectors that recorded six species/species groups of bats during the summers of 2020–2022 within and just outside the range of the cicada emergence along the Potomac River Corridor, Maryland, and Virginia. I observed significantly more total bat acoustic activity within the range of the cicada during the emergence year and the year following than where emergence did not occur. Also, for all individual species and species groups, bat activity increased in the year during and after the emergence within the range of periodical cicadas compared to the year before emergence. My study demonstrates that periodical cicadas cause an increase in bat activity and may suggest a population increase in the areas where the emergence has occurred. Bats of the mid-Atlantic have experienced population declines due to numerous stressors including white-nose syndrome caused by the fungus Pseudogymnoascus destructans, wind turbine development, and habitat fragmentation. One species that has been heavily affected by white-nose syndrome is the little brown bat (Myotis lucifugus). To help conserve the species, understanding their home range and their resource needs is critical. However, little brown bats are small and agile fliers which poses difficulties for tracking them. Traditional foraging studies of species in this genus have used telemetry to obtain triangulations and location estimates of individuals but often leave out data collected from a single bearing as it is difficult to calculate the true location of the animal. During the summer of 2022, I radio-tagged little brown bats from a maternity colony along the Potomac River in Maryland and collected bearings on nine individuals using fixed station telemetry from sunset until bats returned to the maternity roost. We estimated locations from both triangulations and single bearings. I calculated movement models for each individual and fit them to an auto-correlated kernel density estimator (AKDE) of space use. The average 95% auto-correlated kernel density estimates of space use (AKDE) for males was 889 ha ± 424.6 and 699.3 ha ± 129 for adult females. I also assessed the habitat selection of individuals within their home range and across the nearby landscape. I found that bats preferred to use areas closer to water and wetlands and preferred to use areas closer to open habitat within their home range but preferred to use areas further from open habitat across the landscape. Habitat associations were similar to previous little brown bat resource selection studies. However, estimates of space use were larger than those using other movement models. My study was novel in that it incorporated single azimuth observations and periodicity into models of space use, thereby increasing sample size and offering a new framework for future telemetry studies. These estimates of space use can be used by land managers to protect the habitat of this imperiled species.
465

Application of Human-computer Interaction Theories to Information Design on Internet Portals

Rao, Sushma 27 November 2002 (has links)
Internet portals are increasingly becoming a primary source of information. A portal is a gateway to information on the Internet or a hub from which users may locate relevant information (Strauss, 2000). Because university Web sites have various user classes, universities are beginning to adopt the portal concept for their Web sites. The study conducted aimed to determine the effect of tailoring information content and presentation style on a university Web portal. User ratings of information design on three metrics and user task performance measures of time and errors were compared for four prototypes. Three prototypes were built on the basis of user requirements and two Human-computer Interaction (HCI) theories and one was a replica of an existing academic information portal. The three metrics were derived from the HCI theories. The contributions of the study are a determination of user acceptance of and user performance with the tailored presentation styles and three metrics derived from HCI theories that can be used to compare alternative information presentation styles for portals. An important contribution is the remote data collection technique that was used in the study and a time-stamping technique that recorded clicks on hyperlinks. / Master of Science
466

Foraging strategies of Southern Royal Albatrosses, Diomedea epomophora, Campbell Island during incubation

Troup, Christina January 2004 (has links)
Among the species of Diomedea albatrosses, diverse foraging strategies during breeding have been described, indicating species differences in foraging ecology and behaviour. Foraging strategies of Southern Royal Albatrosses, Diomedea epomophora (SRA) breeding on Campbell Island were studied in January – early February 1999 during the latter half of incubation. Movements and activity of ten birds were monitored using satellite transmitters and wet-dry activity recorders. Three birds from a pilot tracking study in February 1997 were also included in some analyses. Foraging strategies, zones used, factors influencing the duration of foraging trips, and the influence of wind conditions were investigated. Foraging activity took place at sites with bathymetric characteristics associated with high productivity: outer shelf and shelf-break zones, with a concentration of activity on a shelf contour south of the Snares Islands. This is in contrast to Wandering (D. exulans) and Gibson’s (D. gibsoni) albatrosses, typically deep oceanic foragers, but is similar to Northern Royal Albatross (D. sanfordi). The maximum distance of foraging trips from the colony was 1250 kilometres (mean 584 +351(SD)). This was closer than for incubating Wandering and Gibson’s Albatrosses but more distant than for Northern Royal Albatross from the Otago Peninsula. The mean duration of 77 foraging trips from 52 nests was 10.11 days for females and 8.76 for males (ns). Foraging trips became shorter as incubation progressed. Foraging trips were shorter, but not significantly so, when the median wind speed throughout the foraging trip was higher. No significant relationship was found between bird mass and duration of foraging trips. The mean cumulative distance flown by the ten birds tracked in 1999 was 4262 km + 1318 (SD). Eight of the ten SRA employed a ‘commute, forage, commute’ foraging strategy, and the other two alternated short bouts of commuting and foraging. Commuting phases were characterised by rapid directional flight with a straight-line distance (range) of 180 km to 800 km between positions 24 hours apart. Foraging phases were characterised by a range of less than 180 km per 24 hour interval and frequent tight turns. Displacement rate between successive uplinks was significantly higher during commuting phases (28.6 kph + 1.93 SE) than foraging phases (15.1 kph + 1.4 SE). Wind strength and direction influenced the timing of the return commute to the colony. SRA covered greater distances at more favourable wind angles relative to flight track (broad reach and close reach) than in head, tail or direct side winds. Birds of low mass (< 8kg) made fewer landings in winds above 40 kph than in lighter winds, whereas heavier birds had a similar level of landing activity across all wind speed bands. One bird was delayed for several days by light winds, and another flew off course during strong winds. Two birds exploited the same window of wind conditions to return to the colony, each flying a similar course in both timing and route. These results define the foraging strategies of SRA during incubation, and demonstrate the influence of wind conditions and other factors on the overall duration of foraging trips and on the timing of commuting and foraging phases.
467

Experimental studies in simple choice behaviour

Monteiro, Pedro Tiago dos Santos January 2013 (has links)
This thesis addresses decision mechanisms in foraging situations, using laboratory experiments with European starlings (Sturnus vulgaris). Building on previous work from the Behavioural Ecology Research Group, I chose the Sequential Choice Model (SCM; reviewed in Kacelnik et al., 2011 − Appendix 1) as a starting point, and tested its premises and predictions generalising it to different experimental protocols. Classical decision models do not relate choice preferences to behaviour towards isolated options, and assume that choices involve time-consuming evaluations of all alternatives. However, previous work found that starlings’ responses to isolated options predict preference in choices, and that response times to single-option encounters are not reliably longer than response times in choices. Since, in the wild, options are normally encountered sequentially, dealing with isolated options can be considered of greater biological, and possibly psychological, significance than simultaneous decisions. Following this rationale, the SCM postulates that when multiple simultaneous stimuli are met they are processed in parallel, each competing against the memory of background opportunities, rather than comparing present options to each other. At the time of launching this research, these ideas had only been applied to protocols involving just two deterministic alternatives and offering no chance to explore the influence of learning history (i.e., how animals learn to choose; see Chapter 4). To increase their relevance and offer more rigorous tests, I generalised them to situations with multiple (see Chapters 2, 4 and 5), and in some cases probabilistic alternatives (see Chapter 3), controlling the learning regime. I combined these extensions with tests of economic rationality (see Chapter 6), a concept that is presently facing sustained debates. Integrating the result of all experimental chapters (see Chapter 7), my results support the notion that behaviour in single-option encounters is fundamental to understand choice behaviour. The important issue of whether choices involve a decision time cost or the opposite, a shortening of response times, remains unsolved, as neither could be evidenced reliably.
468

The trade-off between starvation and predation risk in overwintering redshanks (Tringa totanus)

Sansom, Alex January 2010 (has links)
In order to meet their energy budget animals must often increase their risk of predation, either through their choice of foraging location or by decreasing anti-predation behaviours, which are incompatible with foraging. I investigated the starvation-predation risk trade-off in redshanks overwintering in the area of the Firth of Forth in Scotland over different spatial scales. On a small spatial scale, where redshanks foraged in an area where risk of attack was high I investigated the role of competition for food and decreased individual vigilance within groups and how this related to predation risk, additionally I looked at the relative roles of individual variation in time spent exposed to risk and variation in anti-predation behaviours on individual survival time. On larger spatial scales of 100s of meters and over several kilometres, I considered how choice of overwintering site was affected by predation risk, profitability and population density. Time available to feed increased with increased group size, allowing redshanks to compensate for increased competition and allowing large groups to form, thus decreasing individual predation risk. Individuals that spent less time exposed to attacking predators survived for longer, however individuals constrained by cold weather to spend long periods exposed to risk could increase their survival through increased intake rates and vigilance. On an intermediate spatial scale redshanks selected overwintering sites based on profitability rather than risk, and only used less profitable site when population density was high. On a large spatial scale redshanks increased their use of less profitable sites in warmer weather, but did this without increasing their risk of predation. Overall this suggests that across most spatial scales redshanks can minimise their predation risk by their choice of foraging location, but when forced by weather conditions or competition to be exposed to attack, capture reducing behaviours also reduce predation risk.
469

Trade-offs between the risks of predation and starvation in subtropical granivorous finches

Brandt, Miriam J. January 2007 (has links)
Animal community structures, life histories and individual foraging behaviour are all an outcome of a trade-off between competition for resources (and thus the risk of starvation) and survival (and thus the risk of predation). The relative importance of these factors however, differs between ecosystems, and especially when comparing temperate to tropical ones, we usually find marked differences. The seasonality of tropical ecosystems is much reduced compared to temperate ones, and weather conditions are less extreme. Accordingly tropical systems are characterised by higher species diversity, and different life history traits have been found between temperate and tropical birds. However, how the different environmental factors interact, and how predation and starvation risk vary to cause these differences still remains largely unknown. We studied the feeding behaviour of several granivorous Estrildid finches in scrub savannah habitat in central Nigeria to test how they respond to varying degrees of starvation and predation risk. During field observations and aviary experiments we investigated whether there is seasonal variation in the birds’ foraging behaviour correlating with the abundance of grass seeds and tested how they respond to different group sizes and differing distances from cover (representing a difference in predation risk). Further we also carried out field observation on the natural feeding behaviour of several closely related sympartic Estrildid finches to investigate inter-specific and seasonal differences in competition and microhabitat choice to see if this could explain their coexistence. Finally we studied habitat choice, movement behaviour and breeding biology of the potentially threatened endemic Rock Firefinch (Lagonosticta sanguinodorsalis) between the wet and the dry season via radio-tracking to establish its habitat requirements and gain the first information in its life history traits and population trends. We found little seasonal variation in the species’ foraging behaviour, and parameters that varied did not do so in a consistent manner. Thus, we found little evidence for a seasonal change in the risk of starvation. However, the abundance of several bird species varied widely between seasons and species leaving during periods of food shortage might have released competition for remaining resources. Birds did not show a strong response in their feeding behaviour with respect to cover in either intake rate or timing of feeding. However, intake rate increased with group size, which we believe to be due to scramble competition rather than risk dilution. We therefore conclude that predation did not shape the foraging behaviour of tropical granivorous passerines as markedly as that of temperate ones. Rock Firefinches were found to breed between the late rainy and the early dry season. They selected inselberg habitat, where most nests were found between rocky boulders. During the dry season, when water sources in inselberg habitat had dried out, they had to fly distances of up to 700 m to the gallery forest to get water and this led to the inclusion of more scrub savannah and gallery forest within their home ranges. Daily egg survival was 0.89 ± 0.03 calculated after the Mayfield analysis and most failing nests were depredated probably mainly by lizards. We suggest that in addition to nest predation, water availability might limit breeding time and thus reproductive output of Rock Firefinches. Predation risk did not seem to be of high importance in shaping the birds’ feeding behaviour because there was no seasonal variation in the risk of starvation. We found some suggestive evidence that competition might be important and it is likely that bird populations constantly stay close to carrying capacity. In contrast to temperate regions the need to conserve water might be of higher importance in shaping the birds’ feeding behaviour. High adult survival rates might be due to reduced seasonality in the risk of starvation thereby leading to reduced predation risk on adult birds. High nest predation might also be of higher importance in shaping the life history traits of tropical passerines, but at present this suggestion remains speculative. The results fit into the general framework that there is a trade-off between starvation and predation risk, and in the absence of starvation risk for some species in tropical areas, predation risk is also relatively unimportant.
470

Individual and environmental drivers of the foraging behaviour in a long-lived coastal seabird

Pelletier, Laure 16 September 2013 (has links) (PDF)
To study the impact of environmental changes in a coastal marine ecosystem, it is necessary to use indicator species. It is crucial to understand the foraging performances that proceed from environmental changes. The aim of my thesis was to examine the influence of intrinsic and extrinsic factors on the foraging activity of the little penguins (Eudyptula minor). The thermocline allowed birds to approach optimal behaviour. However, the thermocline is an unstable element. I did not find any effect of individual characteristics on their foraging behaviour and success. My work suggests that environmental conditions are major factors that will influence the behaviour of little penguins, allowing me to conclude that little penguins are good ecological indicators.

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