Thesis (M.Sc.)--York University, 2004. Graduate Programme in Biology. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ99289

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6167. Adviser: Jeffrey D. Brawn. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3552. Adviser: Patrick J. Weatherhead. Includes bibliographical references (leaves 137-162) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6131. Advisers: Gary L. Rolfe; Jeffrey O. Dawson. Includes bibliographical references (leaves 233-242) Available on microfilm from Pro Quest Information and Learning.

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<p>A fundamental condition of the struggle for existence is resource limitation. Optimal foraging theory describes how individuals refine behavior to most efficiently exploit available resources. For colonial breeding animals, such as seabirds, competition for limited resources is amplified by a high density of competitors at feeding grounds near the colony, which can lead to a diversification of foraging strategies that best exploit available resources. Laysan and black-footed albatrosses (Phoebatria immutabilis and P. nigripes, respectively) breed sympatrically and synchronously in dense colonies on small atolls throughout the northwestern Hawaiian Islands. While the distributions and habitat preferences of these congeners are well described, the variability in foraging strategies driven by niche partitioning is not. In chapter 1, I used fine-scale behavioral data from GPS data-loggers to tease apart subtle behavioral nice partitioning between and within Laysan and black-footed albatrosses constrained to poor-nutrient tropical waters during the most energetically-demanding reproductive stage in birds: the brood-guard. Albatrosses showed discrete behavioral partitioning both between and within species, which was driven by differences in nocturnal and diurnal foraging and by sex-specific strategies. Black-footed albatrosses exhibited greater variability in foraging patterns suggesting they may experience strong intraspecific competition at Tern Island. In chapter 2, I employed a novel adaptation of a biochemical diet analysis, quantitative fatty acid analyses, to investigate dietary niche partitioning across the breeding season. This analysis characterized diet of individual adult albatrosses across the breeding season, from incubation to the chick-brood, for the first time in these species. Additionally, this research extended beyond diet characterization to quantify dietary dependence on fisheries-associated resources for these two species. One of the primary threats to albatross is the incidental mortality of birds from fisheries bycatch, therefore, understanding the incidence of fisheries-associated food in the diet of a breeding colony of albatrosses could have important conservation implications. While older birds tended to consume more squid than younger birds, we did not identify an age bias in birds that exploited fisheries resources. Parallel with results from the behavioral analysis in chapter 1, I found that black-footed albatrosses had greater dietary flexibility than Laysan albatrosses at a population level, and a greater degree of dietary specialization at the individual level. In the final chapter, I looked at how the obligatory act of flight feather molt impacted activity levels and space use across the post-breed migrations, when albatrosses are freed from central place foraging constraints, but limited by demands of self-maintenance. I found that activity levels, but not habitat use, were impacted by molt extent. Habitat use appeared to be primarily driven by consistent individual preferences, with birds showing a high degree of site fidelity to their post-breeding molting grounds. A clear decrease in home range size with age indicated that birds spend less time searching for profitable feeding grounds when they are older, likely a product of accumulated memory and experience in these long-lived species.

This dissertation summarizes three investigations in which immunosuppressive effects of environmentally relevant concentrations of dietary methylmercury (MeHg) were assessed in adult non-breeding male kestrels, female kestrels during egg laying, and nestling kestrels. Immunological endpoints included cell-mediated immunity (CMI) using the phytohemagglutinin (PHA) skin-swelling assay and antibody-mediated immune function using the sheep red blood cell (SRBC) hemagglutination assay. Hematology profiles were evaluated over time in adult males and nestlings to monitor immunological and physiological status of kestrels. Primary and secondary immune system organs were examined histopathologically to identify T and B cell-dependent structural changes related to immunosuppressive effects of MeHg. Male kestrels dosed with 3.9 µg/g MeHg in the diet for 13 weeks exhibited suppression of CMI (p = 0.019), elevation in the proportion of heterophils (p < 0.001) and total white blood cell counts (p < 0.001), and a decline in the proportion of peripheral blood lymphocytes (p < 0.001). Primary antibody-mediated immune response was suppressed at 0.6 µg/g MeHg (p = 0.014), but secondary immune function was not adversely effected. Female kestrels were dosed with 2.8 µg/g MeHg in the diet for 13 weeks prior to egg laying and exhibited a higher primary immune response to sheep red blood cells (SRBC) than controls (p = 0.013). Subtle reproductive effects were also apparent including a 4.3-day delay in egg laying (p < 0.001) and depletion of egg mass (p = 0.037), egg volume (p = 0.050), and eggshell thickness (p = 0.004). The quantity of antibody production during egg laying, as measured by anti-SRBC antibody concentrations in egg yolk, did not differ from controls. However, the duration of antibody production was significantly longer for MeHg dosed females (p = 0.007), suggesting immunomodulation occurred among dosed kestrels during egg laying. Nestlings dosed with 0.6 and 3.9 µg/g in the diet for 25 days post-hatch also exhibited suppression of CMI at 11 days of age (p = 0.004) and lymphoid depletion in spleen (p < 0.001) and thymus tissue (p = 0.017). Antibody-mediated immune function was not adversely affected in nestling kestrels. Results from these three investigations suggested suppression of CMI and lymphoid depletion occurred at a dose concentration of 3.9 µg/g MeHg in adult, non-breeding male kestrels and at both 0.6 and 3.9 µg/g MeHg dose concentrations in nestlings. Immunosuppressive effects and immune dysfunction with respect to antibody-mediated immune function occurred at a dose concentration of 2.8 µg/g in female kestrels during egg laying; estrogen-disrupting characteristics of MeHg during avian reproduction cannot be excluded as a potential influence on this response. Immunotoxic effects of dietary MeHg in female kestrels during egg laying were primarily immunosuppressive and targeted T cell-mediated immune function. Cell-mediated immunity was highly sensitive to the immunosuppressive effects of dietary MeHg at low, environmentally relevant exposure concentrations, and at comparatively high doses (> 3 ppm) at which reproductive effects have been demonstrated in kestrels in other investigations.

<p> This study provides the first assessment of demographic and habitat information for pinto abalone (<i>Haliotis kamtschatkana</i>) in San Diego, California, two decades after the closure of all abalone fisheries in southern California. SCUBA surveys conducted from June 2014 to December 2016 indicate that current low densities (0-0.03 individuals/m²) were far below critical thresholds identified for other abalone species (0.15-0.30 abalone/m²) for successful spawning and recruitment. A broad range of sizes were represented (13-146 mm), however, only 95 individuals were found. Some sites showed significant aggregation of adult (> 50 mm) pinto abalone, 30% of adults had a nearest-neighbor within a critical spawning distance of 2 m, and 65% had a neighbor within 5 m, indicating that at least a small proportion of individuals may be capable of reproducing successfully. Pinto abalone showed a significant preference for boulder habitat at a lower relief (&lt; 10 cm) relative to available habitat&ndash; a preference that may influence aggregation around habitat features and enhance reproduction. The frequency, timing, and broad spatial distribution of these surveys was not sufficient to measure patterns in recruitment or changes in abundance, particularly over a strong El Ni&ntilde;o event that occurred during the study period. There is a critical need for consistent long-term monitoring in southern California to better understand demographic and environmental processes affecting recovery and persistence of populations, particularly at the southern edge of the broad range of pinto abalone.</p><p>

<p> Reliable estimates of species abundance, distribution, and population trajectories are critical in conservation and management. However, for many tropical species that information is missing. We conducted Sharp-shinned Hawk (SSHA) searches during the breeding seasons of 2013, 2014, and 2016 in eight montane forest reserves and their adjacent private lands of Puerto Rico. Further, we developed a maximum entropy model (MaxEnt) of the SSHA&rsquo;s potential distribution using the following environmental variables: aspect, canopy closure, elevation, rainfall, slope, and terrain roughness. Elevation accounted for 89.8% of model fit, predicting the greatest probability of occurrence (> 60%) at elevations above 900 m. The model estimated 0.6%Puerto Rico (56.1 km²) has the greatest probability of occurrence. We developed a periodic population matrix model to describe the influence of early life stages on population growth of the Red-tailed Hawk (RTHA) in eastern Puerto Rico. Our results suggest that the RTHA population has an average annual population increase of 5%, with rates differing between highlands (&lambda;_h = 1.05) and 27% lowlands (&lambda;_l = 1.27). Adult survival was the most important population growth parameter, with more effect in highlands (elasticity = 0.86) than in lowlands (elasticity = 0.53). Sensitivity of &lambda; to changes in nestling survival was greater than for other life-stages (sensitivity lowlands = 0.46, sensitivity highlands = 0.48). I developed an open population N-mixture model to estimate abundance, availability, and detection probability of RTHA in the Luquillo Mountains and western Cordillera Central. The abundance estimates were 0.05 RTHA/ha, with an availability of (&phis;) = ~1 RTHA/per survey point and a detection probability (r) = ~0.25. In Luquillo Mountains, abundance was positively influenced by slope and elevation. In the western Cordillera Central, abundance of RTHA was constant across elevation, slope, and canopy closure. Detection probability decreased with increasing slope and wind conditions and showed a gradual small negative decrease with slope with reduced winds conditions. My findings are a contribution to our knowledge of how population traits and ecological constraints imposed by insular environments are influencing distribution, abundance, and population dynamics of raptors to propose management or conservation schemes.</p><p>

Master of Science / Department of Horticulture and Natural Resources / Ryan L. Sharp / Elk in Kansas were an abundant tallgrass prairie species prior to European settlement. Elk were extirpated in the 1870s and reintroduced in the late 1980s. After three decades, wild populations continue to be low in spite of good biological conditions. Broad, low stakeholder acceptance are a suspected limiting factor. Wildlife stakeholder acceptance capacity (WSAC) and tolerance models helped to frame results from an internet based survey (n=460) directed to all Kansas counties. Respondents reported high mean positive wildlife values, acceptance for elk population increase, and significantly (p<0.05) higher personal acceptance for elk than the level of acceptance they perceived in others. Encountering wild elk in Kansas was unrelated to acceptance but strongly predicted providing wildlife habitat on private land. Hunters reported the strongest wildlife attitudes but this result was not correlated with elk acceptance. Intangible benefits (e.g. positive meaningful experiences) strongly affected (p<0.00) wildlife attitudes and elk acceptance. Tangible benefits (e.g. money) was unrelated to wildlife values but respondents who reported tangible benefits from four or more wildlife species showed higher acceptance for elk on personal property than groupings based on other variables. WSAC theory suggests social carrying capacity for elk is significantly above the current population and Kansans are more accepting of wildlife than previously thought. Wildlife managers may be encouraged by these results to conduct their own social feasibility study regarding increasing the elk population to a more ecologically sustainable level.