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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.
61

Environmental, ecological, and fishery effects on growth and size-at-age of Pacific halibut (Hippoglossus stenolepis)

Sullivan, Jane Y. 30 August 2016 (has links)
<p> Size-at-age of Pacific Halibut (<i>Hippoglossus stenolepis</i>) has declined significantly since the 1980s. For instance, the average weight of a 20-year-old female declined from 55 kg in 1988 to 20 kg in 2014. The decline in size-at-age corresponds to a period of declining Pacific Halibut recruitment, spawning biomass, and reductions in catch limits for the directed commercial Pacific Halibut longline fishery. The causes of changes in Pacific Halibut size-at-age are poorly understood. Our project investigates several hypotheses related to declines in size-at-age, including the effects of environmental and ecological variability on growth, and the cumulative effects of harvest and size-selective fishing. Specific potential environmental covariates include the Pacific Decadal Oscillation, which is an index of basin-wide sea surface temperatures, and summer sea surface temperatures along the continental shelf of the Gulf of Alaska. Specific ecological variables include annual biomass estimates of Arrowtooth Flounder (<i>Atheresthes stomias</i>) and Pacific Halibut to investigate the potential role of inter- and intraspecific competition, respectively. We used a population modeling approach to simulate the effects of fishing on size-at-age. We found that the large increase in Arrowtooth Flounder biomass since the 1970s corresponds to declines in Pacific Halibut size-at-age. Our results also suggest that periods of high Pacific Halibut biomass relates to poor growth and low size-at-age. Finally, we found that harvest and size-selective fishing explains between 30 and 65% of observed declines since the 1980s in the Gulf of Alaska, and up to 100% of the declines in Southeast Alaska and British Columbia where harvest rates were high in the 1990s and 2000s. Our findings have implications for fisheries management, including balancing tradeoffs associated with size limits, and understanding how changes in environmental and ecological conditions can shift management reference points such as maximum sustainable yield.</p>
62

Exploring Public Opinion of Urban Wildlife and Effective Use of Urban Wildlife Education in Tucson, Arizona

Baker, Tina M. 07 June 2017 (has links)
<p> I studied current educational efforts about urban wildlife in Tucson, Arizona using three main approaches: a) interviews with key informants, b) analysis of the dissemination of and reaction to informative booklets about urban wildlife, and c) a review of regionally-relevant news articles published online from 2013 to 2015. These triangulated research efforts provide a general snapshot of the relative effectiveness of urban wildlife education practices and result in suggestions for improvement with future efforts. Key informants provided insight into successful human-wildlife conflict resolution and avoidance techniques and successful education practices. An analysis of the dissemination of information on living with urban wildlife, revealed that 53% of the small participating businesses valued the effort and requested additional booklets for their clients. All 45 of the recipients of the educational booklet found them useful and 65% cited them as their only such source of information about wildlife. Thus, I recommend additional concerted dissemination of such materials towards improved education of the public about urban wildlife interactions. Analysis of online news articles revealed that 51% focused on human-wildlife conflicts and, of these, 30% contained information about conflict avoidance. By contrast, 35% of all articles reviewed were strictly educational and yet, of these, 74% addressed conflict avoidance. Thus, I recommend that future media efforts continue this focus on human-wildlife conflict avoidance and resolution strategies. The culmination of this work demonstrates that much work is being conducted towards urban wildlife education and revealed education projects and strategies that may be applied in the future to help facilitate an informed coexistence with urban wildlife.</p>
63

Testing camera trap density estimates from the spatial capture model and calibrated capture rate indices against kangaroo rat (Dipodomys spp.) live trapping data

Walker, Timothy A. 01 November 2016 (has links)
<p>Camera trapping studies often focus on estimating population density, which is critical for managing wild populations. Density estimators typically require unique markers such as stripe patterns to identify individuals but most animals do not have such markings. The spatial capture model (SC model; Chandler & Royle, 2013) estimates density without individual identification but lacks sufficient field testing. Here, both the SC model and calibrated capture rate indices were compared against ten sessions of live trapping data on kangaroo rats (Dipodomys spp). These camera and live trapping data were combined in a joint-likelihood model to further compare the two methods. From these comparisons, the factors governing the SC model?s success were scrutinized. Additionally, a method for estimating missed captures was developed and tested here. Regressions comparing live trapping density to the SC model density and capture rate were significant only for the capture rate comparison. Missed image rate had a significant relationship with ambient nighttime temperatures but only marginally improved the capture rate index calibration. Results showed the SC model was highly sensitive to deviations from its movement model, producing potentially misleading results. The model may be effective only when movement assumptions hold. Several factors such as camera coverage area, microhabitat, and burrow locations could be incorporated into the SC model density estimation process to improve precision and inference.
64

Disruption and disease : how does population management affect disease risk in wild bird populations?

Downing, Beatrice Catherine January 2017 (has links)
Despite the ubiquity of wildlife management, from reintroductions and supplemental feeding to culling and habitat destruction, very little is known of the effects of management practices on species’ social dynamics. Species’ social structure has the potential to affect not only behaviour and evolution but also the transmission of information or disease. Understanding the effects of population management on social behaviour and organisation is a key step in understanding these species’ ecology. This thesis examines the differences between individuals’ roles in the social structure and what this means for the transmission of disease. It demonstrates how similarity in movement behaviour scales with increasing social circles, how seasonality in movement and seasonality in association rates covary as well as detailing post-cull behavioural changes. It finds that there is the potential for certain individuals (most likely non-breeding individuals) to transmit infection far and wide. It reveals the similarities in movement behaviour and body condition that birds share with their pair and social group. It emphasises the importance of autumn and winter movement in the transmission of infectious disease and it follows the short- and long-term changes in social structure and movement behaviour following a cull. Cull survivors were observed to retain a higher proportion of associations with their previous associates and moved less far in the year following the cull than in the year preceding it. This is the first application of social network analysis to quantify social structure before and after culling. The findings suggest that culling an infected population may facilitate rather than constrain the transmission of disease.
65

Influence of landscape- and stand-scale factors on avian communities in open pine ecosystems

Hannah, Taylor Idora 09 September 2015 (has links)
<p> Identifying species occurrence in ecosystems of high conservation concern is especially important in the context of modern landscapes. This study investigated how stand-scale and landscape-scale factors affect priority birds associated with longleaf pine (<i>Pinus palutris</i>) ecosystems. Herein, I compared priority bird occupancy among 12 stand types throughout the historic range of longleaf pine. I found open pine stands positively influenced red-cockaded woodpecker (<i>Picoides borealis</i>) and Bachman&rsquo;s sparrow (<i>Peucaea aestivalis</i>) occupancy, but were not significantly linked to northern bobwhite (<i>Colinus virginianus</i>) and brown-headed nuthatch (<i>Sitta pusilla</i>) occurrence. Landscape- and stand-scale factors affected red-cockaded woodpecker, Bachman&rsquo;s sparrow, and brown-headed nuthatch occupancy. Northern bobwhite occupancy was influenced solely by landscape-scale factors. Red-cockaded woodpecker and Bachman&rsquo;s sparrow were positively influenced by metrics associated with longleaf pine ecosystems suggesting they are effective indicator species. My analysis indicates that using this multi-scale approach is valuable to identifying areas on the landscape of conservation and restoration priority.</p>
66

Demographic and ecological approaches to understanding Ring Ouzel (Turdus torquatus) population declines

Sim, Innes M. W. January 2012 (has links)
Populations of many species are decreasing, but the underlying causes are often poorly understood, impeding effective conservation action. One useful approach is to determine which demographic rates drive variation in population growth rate () and identify ecological and environmental causes. I identified key demographic rates driving the decrease in Ring Ouzel (Turdus torquatus) population size, a species of high conservation concern in the UK, and explored underlying ecological and environmental causes. The number of breeding pairs decreased by 44-100% during 1979-2009 across 13 study areas throughout the UK. The population in my study area in Glen Clunie, Aberdeenshire, Scotland, decreased by 67%, from 39 to 13 breeding pairs, during 1998-2009. Mean  calculated from annual censuses was 0.91. I recorded reproductive success, and used re-sightings of marked individuals to estimate survival rates in each year, thus measuring the mean, variance and covariance among key demographic rates. Prospective elasticity analysis indicated that  was most sensitive to adult survival. However, integrated elasticity analysis, accounting for estimated demographic covariance, indicated that  was most sensitive to first-year survival. Retrospective decomposition of variance indicated that first-year survival contributed most to observed variation in . However, adult survival was low compared with species with similar life histories. Juveniles fledged from early-season broods had higher survival probability during each four-day period post fledging (0.952 ± 0.011) than juveniles fledged from late-season broods (0.837 ± 0.021). Predation was the main apparent cause of mortality. Juveniles foraged on invertebrates in grass-rich areas during June to mid-July, but then switched to feed mainly on moorland berries in higher-altitude, heather-rich, areas during mid-July to early-September. Thus, a variety of habitats providing different food types is required during the late summer. This thesis illustrates the value of integrating demographic and ecological studies to understand population change in species of conservation concern.
67

Ungulate invasion on a Mediterranean island : the Cypriot Mesopotamian fallow deer over the past 10,000 years

Daujat, Julie January 2013 (has links)
No description available.
68

An ecological study of a previously unexploited lynx population during the first two years of a commercial trapping program /

Noiseux, François, 1960- January 1986 (has links)
No description available.
69

Factors influencing alert and escape responses of California Towhees to recreationists| Implications for buffer areas

Mace, Cristhian 07 July 2015 (has links)
<p>Recreational activities have been shown repeatedly to have negative effects on wildlife. Appropriate management to minimize the effects of such activities, especially to species of conservation concern, is therefore a goal of utmost importance. This study characterized the visual ecology and anti-predator behaviors of the California Towhee, <i>Melazone crissalis</i>, in the context of parameterizing models for estimating the size and shape of wildlife buffer areas. Contrary to expectation, explicitly incorporating species-specific data on the towhee's visual system and individual-level data on physiological condition and life history traits did not significantly alter estimated buffer area requirements relative to models based solely on behavior. Similarly, towhees exhibited no differences in average alert or flight initiation distances with respect to direct versus tangential approaches. In contrast, data collected across a variety of habitat types in the field suggest that minimum approaching distances for the birds were highly dependent upon local vegetation parameters that included percent cover, density, and height. In general, more vegetative cover was associated with smaller alert and flight initiation distances. Together, these results suggest that a simple management solution (e.g., calculating buffer areas based on mean alert distance alone) may be adequate for this species, but that local habitat conditions will need to be taken into consideration for optimal management solutions. </p>
70

Ultra-managing nature technology and the re-creation of Eden /

Breen, Kevin Christopher. January 2009 (has links) (PDF)
Thesis (MFA)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Ronald Tobias. Restoring Eden is a DVD accompanying the thesis. Includes bibliographical references (leaves 27-29).

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