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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.
51

Population Dynamics and Habitat Selection of Resident Urban Canada Geese (Branta canadensis) Scottsdale, AZ

January 2011 (has links)
abstract: Populations of resident Canada geese (Branta canadensis) that nest and reside within the contiguous United States have increased at a rate of 7.9% per year to over 3.5 million over the last few decades. Enlarged population levels have resulted in conflicts between geese and humans, including property damage and human health and safety concerns. Noticeable growth of the population of Canada geese in the Indian Bend Wash area of Scottsdale, AZ has been observed in recent years sparking concern that this population will continue to grow at high rates as seen in other urban areas throughout North America. This study was initiated to determine the current population structure, distribution, and productivity of this population of resident geese. During the 2009 to 2010 post-breeding molt, 255 geese were captured and affixed with neck collars allowing individual identification. I conducted surveys from October 2008 to September 2010 and calculated weekly population estimates from mark recapture survey data using the Lincoln-Peterson method. Productivity was also investigated. Nesting was largely limited to one island within the study area, suggesting geese preferentially nest in insular areas to avoid human disturbance. Despite limited nesting opportunities, there was a significant population increase of 15 to 25% from 2009 to 2010 based on population estimates. Goose movement patterns indicate this population has a high level of site fidelity to nesting and molting areas, as has been found in other studies of resident Canada geese. I suggest that management should be implemented to 1) reduce the current population of resident geese through adult removal and 2) limit future recruitment into the population through control of reproduction and habitat modification. / Dissertation/Thesis / M.S. Applied Biological Sciences 2011
52

Ecology of Mearns' Quail (Cyrtonyx montezumae) in the Capitan Mountains of New Mexico

Oaster, Elizabeth A. 20 December 2018 (has links)
<p> Within the United States, Mearns' quail (<i>Cyrtonyx montezumae </i>) are native to Arizona, New Mexico, and Texas. Knowledge regarding Mearns' quail populations in the United States is limited, especially on New Mexico populations. This study was initiated to answer 1) tree canopy cover and vegetation selection, 2) population characteristics, and 3) roost site characteristics of Mearns' quail in New Mexico. Mearns' quail were captured in Lincoln County, New Mexico from May 2015&ndash;May 2017. Fifty-six Mearns' quail (32 M, 24 F) were affixed with a Very High Frequency (VHF) or Global Positioning System (GPS) and VHF combination backpack radio transmitter to monitor movements and survival. The 2,510 points collected from 27 (19 M, 8 F) Mearns' quail showed that on a continuous scale, year-round basis, Mearns' quail utilized 30&ndash;69% tree canopy cover. During the covey, paired and breeding, and nesting and brooding seasons Mearns' quail selected for 30&ndash;39%, 40&ndash;59%, and 40&ndash;69% tree canopy cover respectively. Mearns' quail selected for litter basal cover (P = 0.018) and bare ground basal cover (<i> P</i> = 0.032). Annual survival rate of Mearns' quail was calculated at 0.75. The overall male-female ratio was 0.9:1 with annual variations (capture season 1 0.76:1, capture season 2 1.6:1). Juvenile-adult ratios were 2.25:1 with annual variations as well (capture season 1 5:1, capture season 2 0.6:1). In regards to roost site characteristics, Mearns' quail selected for forb basal cover (<i>P</i> = 0.015) and distance to closest tree 1&ndash;3 m in height (<i>P</i> &lt; 0.001). While visual obstruction (<i>P</i> = 0.056), grass basal cover (<i>P</i> = 0.060), litter basal cover (<i>P</i> = 0.052), and bare ground basal cover (P = 0.051) were not statistically significant, there is biological significance. These results help managers better understand habitat requirements and population characteristics of Mearns' quail in New Mexico.</p><p>
53

Ecosystem Impacts and Space Use of Double-Crested Cormorants in a Southeastern Reservoir System

Moran, Leah L.K. 08 September 2018 (has links)
<p> Double-crested Cormorants are expanding their breeding range to historic wintering and migratory regions, such as Guntersville Reservoir in Alabama. This study lends insight into how cormorants breeding in a temperate ecosystem impact plants, trees, soil and bird communities as well as home range and movement of cormorants during the breeding season and whether they reside on this reservoir year-round. Results suggest that breeding cormorants have a negative impact on this ecosystem and do not move far from colony sites. Stable isotopes from cormorants and prey fish suggest that cormorants are migrating from this system after breeding, potentially to a marine source. This study corroborates past studies of negative impacts of cormorant colonies, and provides novel results of how southeastern cormorants use and move on Guntersville Reservoir. This thesis can provide biologists information on how best to control populations and mitigate impacts on this and other similar southeastern systems.</p><p>
54

Using Stable Isotope Analysis to Infer Breeding Latitude and Migratory Timing of Juvenile Pacific-Slope Flycatchers (Empidonax difficilis)

Moffitt, Emily B. 17 August 2017 (has links)
<p> Effective conservation of migratory species is hindered by a lack of knowledge of population links between breeding, wintering and stopover habitats. The Pacific-slope flycatcher (<i>Empidonax difficilis</i>) is one of the many Neotropical migratory songbirds whose populations are steadily declining throughout western North America. This research contributed to the assessment of connectivity in this species by inferring relative breeding origins and habitat selection of juvenile birds that migrate along the Pacific Flyway to the South San Francisco Bay Area in the fall. Feather data collected from July 20 to October 12, 2014 were analyzed for three stable isotopes (&delta;<sup>2</sup>H, &delta;<sup>13</sup>C, &delta;<sup> 15</sup>N). Findings revealed that populations migrated sequentially from western regions throughout expected breeding latitudes, with early season migrants most likely coming from the more southern, warmer, and dryer regions of northern California, Oregon, and southern Washington while late season migrants had probable origins in the more northern, cooler, and wetter regions of northern Washington and southwestern British Columbia. This study provided new information on the annual cycle and migratory timing of Pacific-slope flycatchers, and lays the foundation for future assessments of migratory connectivity of this species.</p><p>
55

Growth of Atlantic salmon (Salmo salar) in freshwater

Sigourney, Douglas Bradlee 01 January 2010 (has links)
Growth plays a key role in regulating ecological and population dynamics. Life history characteristics such as age at maturity, fecundity and age and size at migration are tightly linked to growth rate. In addition, size can often determine survival and individual breeding success. To fully understand the process of growth it is important to understand the mechanisms that drive growth rates. In Atlantic salmon, growth is critical in determining life history pathways. Models to estimate growth could be useful in the broader context of predicting population dynamics. In this dissertation I investigate the growth process in juvenile Atlantic salmon (Salmo salar). I first used basic modeling approaches and data on individually tagged salmon to investigate the assumptions of different growth metrics. I demonstrate the size-dependency in certain growth metrics when assumptions are violated. Next, I assessed the efficacy of linear mixed effects models in modeling length-weight relationships from longitudinal data. I show that combining a random effects approach with third order polynomials can be an effective way to model length-weight relationships with mark-recapture data. I extend this hierarchical modeling approach to develop a Bayesian growth model. With limited assumptions, I derive a relatively simple discrete time model from von Bertalanffy growth that includes a nonparametric seasonal growth function. The linear dynamics of this model allow for efficient estimation of parameters in a Bayesian framework. Finally, I investigated the role of life history in driving compensatory growth patterns in immature Atlantic salmon. This analysis demonstrates the importance of considering life history as a mechanism in compensatory growth. Information provided in this dissertation will help provide ecologists with statistical tools to estimate growth rates, estimate length-weight relationships, and forecast growth from mark-recapture data. In addition, comparisons of seasonal growth within and among life history groups and within and among tributaries should make a valuable contribution to the important literature on growth in Atlantic salmon.
56

Conservation and ecology of four sympatric felid species in Bukit Barisan Selatan National Park, Sumatra, Indonesia

McCarthy, Jennifer Lynn 01 January 2013 (has links)
Indonesia has one of the highest diversities of plants and animals in the world and nine of the eleven felid species present in Southeast Asia are found in Indonesia. Yet, Indonesia now leads the world in the number of threatened and endangered mammal and bird species, with new species constantly added to the list. The biggest factor driving the disappearance of wildlife in Indonesia is large-scale habitat loss and degradation. The country is losing its forests at the fastest rate of any nation in the world. In Sumatra alone, nearly 3.1 million hectares of forest were lost in the past decade, and lowland forests have all but disappeared. In the face of continued habitat loss and fragmentation, and a continually increasing human population, it is becoming increasingly apparent that we have to gain some knowledge of these species on Sumatra in order to create effective conservation initiatives, else we risk losing them for good. The present project was initiated to gain such information on small felids in Sumatra. There were three elements to our study: camera trapping, live trapping, and an analysis of human-felid conflict. The camera trapping portion of our study allowed the examination of the distribution, habitat preferences, and activity patterns of small felids on Sumatra. This is the first such information on these species from anywhere in their range and is invaluable to managers as they prioritize habitats for conservation. Our study was the first to attempt live trapping and collaring of small felid species in Sumatra, and one of a very few which had been conducted in the tropical forests of Asia. We were able to capture and collar the first golden cat ever collared in Indonesia, and only the third in the world. The information gained from tracking her movement once again provides invaluable information on the ecology of this species in Sumatra. Finally, we conducted surveys of human-small felid conflict around BBSNP. Prior to our study, human conflict with small felids was not thought to be a major factor in their conservation in Southeast Asia because it was rarely reported to governmental officials. Our study is the first in Southeast Asia to characterize this conflict and its effect on the conservation of small felids in Sumatra. We also assessed the efficacy of simple education and mitigation techniques in reducing conflict, creating a successful model that can be replicated throughout the species range. Overall, this study provides valuable knowledge on the Sunda clouded leopard, the Asiatic golden cat, the marbled cat, and the leopard cat, generating information which may be used for their more effective conservation in Sumatra.
57

Population structuring in Southern Africa zebras

Moodley, Yoshan January 2002 (has links)
Bibliography: leaves 157-172.
58

The movements, habitat use, and population assessment of western pond turtles (Actinemys marmorata) in a Southern California seasonal wetland

Nerhus, Barry S., Jr. 03 June 2016 (has links)
<p> This study investigates the population dynamics, movements, and habitat use of a population of western pond turtles in Orange County, California from 2008-2012 using radio telemetry and mark-recapture data. Western pond turtles have been thought to be declining throughout their range. However, few studies have documented their status in southern California, where urbanization has changed the landscape drastically in recent decades. I individually marked 236 pond turtles using hoop-net funnel traps and estimated the population size at 308 individuals, which is the largest estimate reported in southern California. Mean capture per unit effort was 5.03&plusmn;0.87. Mean female carapace length (CL) (142&plusmn;14mm) was not significantly larger than males (139&plusmn;14 mm). I also documented 20 nest and 9 estivation locations. Mean distances included 176 &plusmn;130.80 meters (m) and 91&plusmn;58.6 m. These data identify the population demography, which can be a metric of population stability. Other known populations need to be estimated to determine their regional status.</p>
59

Population Dynamics of Northern Cardinal and Carolina Wren in an Urban Forest Fragment| Safe Refuge or Ecological Trap?

Karmacharya, Binab 28 January 2016 (has links)
<p> Conserving bird populations in urban landscapes often depends on interactions between extinction, recolonization, and survival in remnant habitat patches such as small nature preserves. Thus, determining the ecological value of small nature preserves to birds is a necessary step towards an informed conservation strategy. As such, I conducted a year round capture-mark-recapture study from April 2010 to March 2014 to examine population dynamics of Northern Cardinals (<i>Cardinalis cardinalis</i>) and Carolina Wrens (<i> Thryothorus ludovicianus</i>) in a 41.7-ha nature preserve embedded in an urban matrix. More specifically, we examined variation in survival, recruitment, and realized population growth rates relative to year, season, sex, age, and wing length (as a proxy for body size) to investigate attributes that affect individual survival and to assess whether the reserve served as a population source or sink. The overall annual apparent survival rate of Northern Cardinals (0.520 &plusmn; SE 0.050) was higher than that of the Carolina Wrens (0.349 &plusmn; 0.050), and estimates in both species were similar to regional baseline estimates. The survival rates for adults were significantly higher than for immatures in both species, with body size having a positive influence on survival. Seasonal variation in survivorship was evident only in Northern Cardinals, being highest in the winter and lowest during the breeding season. Average annual population growth rate was slightly greater than 1.0 for both species, indicating stable or perhaps modestly increasing populations. These results represent the first published full annual cycle estimates of survival and population growth relative to age, sex, and body size for non-migratory passerines. Our results suggest that urban forests can provide the necessary resources to sustain growing populations of locally common birds. Furthermore, our demographic estimates derived from two healthy bird populations can serve as target values for other species of conservation concern within human-modified landscapes. </p>
60

Environmental drivers of deer population dynamics and spatial selection in southeast Alaska

Gilbert, Sophie L. 08 October 2015 (has links)
<p> The coastal temperate rainforest is one of the rarest ecosystems in the world, and a major portion of the global total is found in Southeast Alaska. In this ecosystem, Sitka black-tailed deer are the dominant large herbivore, influencing large carnivores that prey on deer such as wolves and bears, as well as plant species and communities through browsing. In addition, deer play an important economic and cultural role for humans in Southeast Alaska, making up the large majority of terrestrial subsistence protein harvested each year as well as providing the backbone of a thriving tourism industry built around sport hunting. Given the importance of deer in this system, there remain a surprisingly large number of key gaps in our knowledge of deer ecology in Southeast Alaska. </p><p> These knowledge gaps are potentially troubling in light of ongoing industrial timber-harvest across the region, which greatly alters habitat characteristics and value to wildlife. This dissertation research project was undertaken with the aim of filling several connected needs for further understanding deer ecology, specifically 1) patterns of reproduction and fawn survival, 2) population dynamics in response to environmental variability, and the underlying drivers of spatial selection during 3) reproduction and 4) winter. To fill these knowledge gaps, I developed robust statistical tools for estimating rates of fawn survival, and found that fawns must be captured at birth, rather than within several days of birth, in order to produce unbiased estimates because highly vulnerable individuals died quickly and were thus absent from the latter sample. I then use this robust approach to estimate vital rates, including fawn survival in winter and summer, and developed a model of population dynamics for deer. I found that winter weather had the strongest influence on population dynamics, via reduced over-winter fawn survival, with mass at birth and gender ratio of fawns important secondary drivers. </p><p> To better understand deer-habitat relationships, I examined both summer and winter habitat selection patterns by female deer. Using summer-only data, I asked how reproductive female deer balance wolf and bear predation risk against access to forage over time. Predation risks and forage were strong drivers of deer spatial selection during summer, but reproductive period and time within reproductive period determined deer reaction to these drivers. To ensure adequate reproductive habitat for deer, areas with low predation risk and high forage should be conserved. Focusing on winter, I evaluated deer spatial selection during winter as a response to snow depth, vegetation classes, forage, and landscape features. I allowed daily snow depth measures to interact with selection of other covariates, and found strong support for deer avoidance of deep snow, as well as changes in deer selection of old-growth and second-growth habitats and landscape features with increasing snow depth. Collectively, this dissertation greatly improves our understanding of deer ecology in Alaska, and suggests habitat management actions that will help ensure resilient deer populations in the future.</p>

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