UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

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Subject: search.filters.subject.movement ecology

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    INTEGRATING BIOTELEMETRY AND HYDROACOUSTIC DATA TO ESTIMATE THE ABUNDANCE OF THE FALL SPAWNING RUN OF ATLANTIC STURGEON IN THE MARSHYHOPE CREEK-NANTICOKE RIVER SYSTEM
    (2022) Coleman, Nicholas; Secor, Dr. David H; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Once thought to be extirpated, fall spawning runs of Atlantic sturgeon (Acipenser oxyrinchus) have been rediscovered in the Nanticoke River-Marshyhope Creek system in Maryland and are currently listed as an endangered species within the Chesapeake Distinct Population Segment. Previously tagged adults predominate survey captures, suggesting a very small population size. A key challenge is to estimate abundance for such a small population distributed between presumed spawning reaches of the connected Nanticoke River and Marshyhope Creek. This study leverages data collected from a dense telemetry receiver array and multiple side-scan sonar surveys conducted from August to October to estimate reach specific and superpopulation abundances in 2020 and 2021. I modified an approach that integrates mobile hydroacoustic data with biotelemetry, here applying for stationary telemetry receiver data. In 2020 and 2021, I estimated that 36 (95% confidence interval: 25-55) and 74 (95% confidence interval: 52-109) sturgeon used the Nanticoke River-Marshyhope Creek system, respectively. The higher estimate in 2021 coincided with higher sonar count data and low and stable river flows and temperature. Still, this large difference has no clear cause. Overall, run estimates support previous hypotheses that the Nanticoke system supports a very small population and that both the Marshyhope Creek and upper Nanticoke River serve as important areas for spawning activity. Going forward, enhanced sampling of the Upper Nanticoke River and targeted analysis assessing the relationship between phenology and environmental conditions would further develop our understanding of interannual changes in spawning run abundance.
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    TIME IS ENERGY: DRIVERS OF MIGRATORY AND NON-MIGRATORY MOVEMENTS BY SOARING BIRDS
    (2020) Mallon, Julie Marie; Fagan, William F; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Vultures are obligate scavengers and search over large areas for carrion, which is ephemeral. To profit from carrion, they are also obligate soarers that rely on the availability of environmental updrafts to subsidize flight. This restricts their flight spatially and temporally to where and when strong updrafts are available. In this dissertation, I investigate how Turkey Vultures (Cathartes aura) use stopovers to both avoid inclement weather and to replenish spent fuel reserves, as well as how the timing of movement activity differs according to flight mode.Using GPS-tracking data from four migratory Turkey Vulture populations, I evaluated how Turkey Vultures respond to changing weather conditions. During stopovers, movement activity was positively correlated with conditions that promote thermal development, suggesting not all stopovers are used for weather-avoidance. Turkey Vultures began stopovers immediately in response to deteriorating weather conditions but their departure from stopovers was delayed relative to improvements in weather, behavior that is consistent with an energy-minimization strategy. I estimated total energetic costs for each migration and identify probable refueling stopovers. Only long-distance Turkey Vulture migrants regularly stop to feed. Overall migratory costs are driven by migration duration, and therefore are lower in the spring when vultures migrate faster, which may contribute to seasonal differences in flight behavior. Last, I compared the non-migratory movements of 49 avian species to test for the influence of flight mode on the timing of movement activity. Terrestrial soaring birds began activity later and stopped activity earlier than other birds. This study demonstrates that flight mode influences temporal patterns of daily movement activity of birds. This dissertation enhances our understanding of how soaring birds cope with the temporal and spatial restrictions on their movements. During non-migration, soaring birds are active for longer proportions of the day to search for food over greater spatial areas than flapping birds. During migration, total energetic costs are driven more by migration duration than by behavior. Therefore, an energy minimization strategy for Turkey Vultures is also a time minimization strategy and vultures are expected to optimize their migration so that they spend the fewest days migrating as possible.
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    THE EFFECT OF SUMMER STORM EVENTS AS A DISTURBANCE ON THE MOVEMENT BEHAVIORS OF BLACK SEA BASS IN THE SOUTHERN MID-ATLANTIC BIGHT
    (2019) Wiernicki, Caroline Jane; Secor, David H; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Storm events are a key disturbance in the Middle Atlantic Bight (MAB), driving thermal, hydrodynamic, and acoustic perturbations on demersal fish communities. Black sea bass are a model MAB species as their sedentary behavior exposes them to storm disturbances. I coupled biotelemetry with an oceanographic model, monitoring black sea bass movement behaviors during the summer-fall of 2016-2018. Storm-driven changes in bottom temperature (associated with rapid destratification) had the greatest effects on fish movement and evacuation rates, while the cumulative effects of consecutive storms had little to no observed effect. Storms also generate substantial noise, but the hearing frequencies of black sea bass are currently unknown. I conducted a quantitative literature analysis on fish hearing based on swim bladder elaboration, successfully classifying detected sound frequency ranges among fishes, including black sea bass. Climate change will likely alter the intensity of MAB storms, prioritizing research on their impacts to fish communities.
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    ECOLOGICAL CAUSES AND CONSEQUENCES OF NON-BREEDING MOVEMENTS IN A DECLINING MIGRATORY SONGBIRD, WOOD THRUSH (HYLOCICHLA MUSTELINA)
    (2019) Stanley, Calandra Quinn; Dudash, Michele R; Marra, Peter P; Behavior, Ecology, Evolution and Systematics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In this dissertation I evaluate the ecological correlates of non-breeding space-use strategies and how these drive within and between season movement dynamics in a declining migratory songbird, wood thrush (Hylocichla mustelina). In Chapter 1, I deployed high-resolution GPS transmitters across 5 breeding populations to quantify habitat selection as wood thrush moved across the annual cycle. I found seasonal variation in habitat selection at the regional, landscape and local scales which suggests the factors driving the evolution of habitat selection preferences vary across seasons and environmental conditions. In Chapter 2, I combined radio telemetry and GPS tracking to examine how environmental conditions drove space-use strategies during the non-breeding stationary period. I found evidence that both small- and large-scale movement dynamics were dependent on moisture levels on tropical non-breeding grounds. At small spatial scales, dry conditions drove low food availability, reduced individual body condition and these individuals had larger home ranges. In this same chapter I integrated archival GPS tag data to demonstrate that wood thrush from across the breeding range engaged in permanent large-scale mid-winter shifts in home ranges and, similar to radio-tagged birds, that individuals from wetter, higher quality habitats were more likely to use this strategy. I suggest that the facultative movements are a condition-dependent strategy allowing wood thrush to find alternative habitats as conditions deteriorate across the dry season in their non-breeding grounds. Finally, to determine how food availability may influence timing of spring migration, I performed a food manipulation experiment with captive wood thrush in Chapter 3. I found that food availability and body condition modulated the intensity, but not onset, of migratory restlessness (Zugunruhe), an index of migratory disposition in captive birds. These results suggest that non-breeding food limitations could constrain migration preparation in wood thrush. Low food availability also advanced the onset of migratory fattening. I suggest that advancing migratory fattening when food availability is low may provide a mechanism to flexibly adjust migration timing under poor environmental conditions. Together these findings suggest that wood thrush exhibit a diversity of behavioural mechanisms to handle environmental heterogeneity across the annual cycle.