71 |
A multi-scale investigation of factors limiting bull trout viabilityBowerman, Tracy E. 07 June 2013 (has links)
<p> Effective conservation strategies for imperiled species require an understanding of processes that influence fitness throughout the organism's life cycle and across the range of habitats needed to complete that cycle. I evaluated factors that affect population viability of bull trout <i>Salvelinus confluentus, </i> a threatened freshwater char species, throughout individual life stages and over the entire life cycle. </p><p> I assessed the relationship between bull trout egg incubation success and environmental variables. Egg survival was negatively related to the percent of fine sediment in redds and positively related to hydraulic conductivity and the strength of downwelling. Next, I quantified juvenile bull trout survival rates and described movement patterns for this life stage. Juvenile bull trout emigrated from natal headwaters into larger rivers throughout the entire year and across a range of sizes. Estimates of juvenile survival rates improved dramatically when emigration was incorporated into the analysis. </p><p> I integrated my observations of bull trout survival, growth, and movement to create a life-cycle model, which I used to better understand how populations respond to changes in specific demographic rates. Bull trout populations were particularly sensitive to changes in juvenile growth and survival. The relative effect of changes to fertility rates and adult survival varied depending upon whether a population was composed primarily of large, migratory, or smaller, resident individuals. Dispersal helped to lower the probability of extinction for small or declining populations when neighboring populations were stable. </p><p> My research demonstrates that bull trout require access to habitats throughout entire watersheds to maintain population viability. My results suggest that limiting anthropogenic sources of fine sediment and maintaining areas of channel complexity that promote downwelling can be important for bull trout embryo survival. Management decisions should also consider the diverse behavior of juvenile bull trout and the wide range of habitat they use. Additionally, connectivity between populations is likely to be important for declining populations to persist. The diversity of life-history strategies expressed by bull trout helps maintain demographic stability within and among populations. As such, preservation of habitat integrity and full life-history diversity is imperative for conservation and recovery of bull trout populations range-wide.</p>
|
72 |
Hatchling sex ratios and nest temperature-sex ratio response of three South Florida marine turtle species (Caretta caretta L., Chelonia mydas L., and Dermochelys coriacea V.)Rogers, Micah Marie 14 August 2013 (has links)
<p> South Florida's loggerhead (<i>Caretta caretta</i>), green (<i>Chelonia mydas</i>) and leatherback (<i>Dermochelys coriacea </i>) sea turtles hatchling have environmentally determined sex. The <i> in situ</i> nest mean hatchling sex ratios (SR) were highly femalebiased: loggerhead <i>F</i>=0.89) and green turtle <i>F</i>=0.81; leatherback's SR was nearly balanced (0.55<i>F</i>). Nest temperatures and SRs differed between leatherbacks and loggerhead and green turtles. The latter two did not differ. The loggerhead response parameters were estimated within biological limitations by both 50-65% of incubation and mean middle 1/3 temperature. The maximum middle 1/3 temperature was the best-fit predictor for green turtles. No best-fit sex ratio-temperature response could be identified for leatherbacks. Clutches incubating under natural conditions can vary greatly in SR; TRT differences may account for differences among species' sex ratios.</p>
|
73 |
Nature's improvement : wildlife, conservation, and conflict in Quebec, 1850-1914Ingram, Darcy. January 2007 (has links)
This dissertation presents a new perspective on the history of conservation in North America. In contrast to historiography that locates conservation-oriented approaches to the North American environment as the product of late-nineteenth-century concerns within Canada and the United States, this study links wildlife conservation in Quebec directly to longstanding European land tenure, estate management, and associational strategies. Through a range of materials including state documents, associational records and personal and family papers, I show how advocates of fish and game protection in the province drew heavily on Old World customs and traditions, particularly those of British landowners, who displayed in their varied social, economic, and political commitments an ongoing engagement with improvement. These 'patrician sensibilities,' I argue, formed the basis of the regulatory system that developed in Quebec during the period 1850-1914, first on the remote salmon rivers of the north shore and Gaspe peninsula, and by the First World War on the bulk of the province's best and most easily accessible hunting and fishing territories. In addition to the regulatory strategies that developed during this period, the dissertation deals with forms and limits of resistance on the part of aboriginal and non-aboriginal subsistence, commercial, and sport hunters and fishers. The dissertation's major contribution lies in its demonstration of the longstanding patterns that underpinned the development of conservation strategies in North America. Class and gender are central to the project, and it also has important implications for our understanding of civil society and state formation.
|
74 |
Status of a Translocated Florida Sand Skink Population After Six Years| Establishing and Evaluating Criteria for SuccessEmerick, Adam Ryan 28 March 2015 (has links)
<p>The translocation of organisms is becoming a frequently used tool in conservation biology. There are, however, a disproportionate number of unsuccessful attempts translocating populations of herpetofauna. Logistical and temporal limits of monitoring, combined with ambiguous metrics concerning “success,” have led to few advances regarding reptile translocations. Successfully established and persistent populations are those in which both the founding population and subsequent generations show consistent or positive levels of survival and reproduction. A small population of the threatened Florida Sand Skink (<i>Plestiodon reynoldsi</i>) was translocated in 2007. Data collected from 2007 to 2009 confirmed survival and reproduction among the founding individuals, but the sampling did not include a long enough period to allow for the evaluation of the survival and reproduction of individuals born on the site. In this study, individuals were collected during two separate sampling events, one during the third spring and one during the sixth spring after the translocation occurred. Survival estimates, reproduction, population size and generation structure were calculated by combining and analyzing data from all years post-translocation. The numbers of both total and new individuals captured in the sixth year exceeded captures from every prior sampling event since monitoring began in 2008. Founding individuals represented only 14% of the total individuals captured, while the number of individuals born on site continued to increase. The proportion of recruits and increased number of hatchlings despite the loss of founders shows that the filial generations are producing offspring. The methods utilized in assessing this translocation effort will further the understanding of the population dynamics of the Florida Sand Skink and allow for more informed decisions in future management studies of this threatened species. </p>
|
75 |
Habitat Use of the Southern Flying Squirrel (Glaucomys volans) in Bluff Forests of Southwestern IllinoisDunham, Loren N. 20 February 2015 (has links)
<p> Increased agriculture and urbanization in southwestern Illinois have severely fragmented the forests of the region. Habitat fragmentation may cause lower species richness, population declines, or extirpation due to phenomena such as edge effects, inbreeding depression, and stochasticity. The effects of habitat fragmentation on suburban wildlife are poorly understood, especially for small mammals such as the Southern Flying Squirrel (<i>Glaucomys volans</i>). Flying squirrels are arboreal rodents whose presence in a forest is indicative of habitat quality, as this species prefers mature and relatively open forest stands. Flying squirrels can be found in the forested areas of the Southern Illinois University Edwardsville (SIUE) campus. Demographic features of this population and habitat use among forest patches were unknown. Artificial nest boxes were utilized to perform a mark-recapture study of the flying squirrel population as well as examine habitat use. Objectives were to obtain demographic information, and to create a predictive habitat model relating habitat characteristics to presence or absence of nest box materials using logistic regression. Study sites consisted of 145 randomized plots in three forest patches located within the SIUE campus, which were monitored November 2013 through October 2014. A model was generated for combined activity (nesting or feeding materials were present) at plots, which contained forest age, dominance of hard mast at a plot, tree density, topographic position, richness of the shrub layer, and the 90th percentile diameter at breast height. Habitat models were also generated for specified response variables of feeding material presence and nesting material presence. The top model for predicting feeding material presence in a nest box contained dominance of hard mast on a plot, richness of the shrub layer, and basal area of logs. The top model for predicting nesting material presence in a nest box contained the shrub layer stem count, roughness of the nest box tree bark, proximity to edge, cavity count, and the average hard mast dominance in the area surrounding the plot. Models tended to include characteristics regarding hard mast dominance and refugia, suggesting nest box use was influenced by avoidance of predation and food resource availability.</p>
|
76 |
Assessments of Surface-Pelagic Drift Communities and Behavior of Early Juvenile Sea Turtles in the Northern Gulf of MexicoHardy, Robert F. 04 December 2014 (has links)
<p> Knowledge of species distribution and habitat associations are essential for conservation measures. Such information is lacking for many marine species due to their occupancy of broad and ephemeral habitats that are difficult to access for study. Sea turtles, specifically the surface−pelagic juvenile stage of some species, are a group for which significant knowledge gaps remain surrounding their distribution and habitat use. Recent research has confirmed the long−standing hypothesis that the surface−pelagic juvenile stage occurs within surface−pelagic drift communities (SPDC). Within the North Atlantic and surrounding basins, the holopelagic macroalgae <i> Sargassum</i> spp. dominates SPDC and serves as a remotely−detectable indicator of SPDC. The present study focuses on surface−pelagic habitats of four sea turtle species and addresses knowledge gaps using two approaches: habitat mapping and behavioral examination. Remote sensing techniques were used to identify SPDC, and satellite telemetry to examine behavior. This work was conducted in three parts and is presented in three chapters. </p><p> Imagery collected from the Landsat satellites (5 and 7) was used to quantify the area of SPDC (km<sup>2</sup>). Approximately 1,800 Landsat images collected from 2003–2011 were examined for SPDC. The first chapter discusses the abundance, seasonality, and distribution of SPDC within the eastern Gulf of Mexico waters where surface−pelagic green, hawksbill, Kemp’s ridley, and loggerhead turtles are known to occur. SPDC was found year−round within the eastern Gulf of Mexico, and the amount of habitat peaked during summer months. The amount of SPDC within the eastern Gulf of Mexico varied annually with peaks in 2005, 2009, and 2011. High concentrations of SPDC were discovered within offshore waters of the northeastern Gulf of Mexico and southern West Florida Shelf. </p><p> Within the second chapter, the behavior of 10 surface−pelagic juvenile Kemp’s ridleys was examined using satellite telemetry. Using remotely−sensed imagery, the sea surface habitats used by tracked turtles were examined. Surface−pelagic juveniles are hypothesized to be principally passive drifters. The behavior of tracked turtles was examined to determine if they exhibited periods of active and passive behavior, which may indicate periods of swim and drift. The proximity of tracked turtles to remotely−detected SPDC was examined when coincident Landsat imagery was available (within one day of the turtle’s position). Turtles were tracked for 36.5 days (mean) and exhibited primarily passive behavior during the tracking period. The satellite transmitters messaged frequently and reported temperatures significantly higher than sea surface temperatures. Landsat imagery was available coincident to the tracks of nine individuals. SPDC was present within 74% of images, and the mean distance between tracked turtles and SPDC was 54 km. Close associations between tracked turtles and SPDC were documented for four individuals. Results suggest that the tracked turtles spent a majority of the time drifting within SPDC. </p><p> The final chapter discusses the density of SPDC within northern and western Gulf of Mexico waters from 2009–2011. Seasonal abundance peaks occurred throughout the study area, but the timing varied. SPDC peaked earlier (late spring) within the northwestern Gulf of Mexico. Moving eastward, the timing of seasonal peaks shifted progressively later during the year. Within the western portions of the study area, SPDC was found to be significantly higher than in the eastern Gulf of Mexico. </p><p> The eastern Gulf of Mexico may provide critical developmental habitats for several North Atlantic sea turtle species. Additional study is necessary to determine if portions of the western Gulf of Mexico could serve in a similar capacity. SPDC is extremely vulnerable to anthropogenic impacts, specifically oil spills and the occurrence of persistent marine debris. Conservation of SPDC may be challenged by its ephemeral nature; however, the results presented herein could advise conservation efforts (e.g., delineation of critical habitat). The present study described spatial patterns of SPDC occurrence, regions of high abundance, and seasonality. The description of the behavior surface−pelagic sea turtles offers refinements to the spatial distribution of this life stage. These results, coupled with information on circulation patterns and the distribution of sea turtle nesting beaches, can be used to better predict when and where sea turtles and SPDC may be found. For example, the year−round persistence of SPDC within the eastern Gulf of Mexico and the location of major nesting beaches located upstream support the area’s designation as critical habitat for surface−pelagic green, hawksbill, Kemp’s ridley, and loggerhead turtles.</p>
|
77 |
Orang-utan conservation : epidemiological aspects of health management and population geneticsK.Warren@murdoch.edu.au, Kristin Shannon Warren January 2001 (has links)
This research addressed two important issues concerning conservation of orang-utans in
Indonesia, the prevalence of diseases in orang-utans at reintroduction centres and the
extent of intra-subspecific genetic variation between isolated populations of Bornean
orang-utans. The research was conducted at the Wanariset Orang-utan Reintroduction
Centre in East Kalirnantan fiom 1994 to 1997, during which time extensive field
excursions were made throughout Borneo, and at the Biomedical Primate Research
Centre in the Netherlands in 1998.
Analysis of clinical records fiom 1991 to 1997 showed that during this period 339
orang-utans were admitted to Wanariset, of which 96 (28.3%) died and 108 (31.8%)
were released. Studies were designed to identify and determine the prevalence of
diseases, specifically gastro-intestinal parasites, tuberculosis and certain viral diseases.
Further studies defined the factors associated with mortalities of orang-utans at the
reintroduction centre.
Gastro-intestinal parasites, in particular Strongyloides spp. and Balantidium coli, posed
health problems for rehabilitant orang-utans. Strongyloides spp. and Strongyle sp. eggs
and B. coli were detected in faecal samples from new arrivals, rehabilitant, released and
wild individuals. Trichuris trichura was present in new arrivals, released and rehabilitant
orang-utans, whereas Ascaris sp., and Cyclospora sp. were present only in rehabilitants.
There was a high prevalence of B. coli in new arrivals (41.6%), rehabilitants (100%) and
released individuals (100%) and a low prevalence in wild individuals (12.5%). Faecal egg counts of individuals infected with Strongyloides spp. showed that 47.8% of
rehabilitants and 14.3% of new arrivals had egg counts over 1000 eggs/gm, 81.8% of
released individuals had egg counts less than 500 eggslgm and all wild individuals had egg
counts less than 100 eggs/mg. Strongyloidosis was the primary cause of death (21.9%)
of rehabilitant orang-utans, prior to the incorporation of oral ivermectin into the parasite
control program.
There was a low prevalence of tuberculosis, which was detected in one individual
(0.8%) and suspected to have caused the death of two others (2.1% of deaths).
Diagnosis of tuberculosis in orang-utans was complicated by inaccuracies and
difficulties in interpreting the diagnostic tests commonly used in humans and nonhuman
primates. Further research is required to develop more reliable and accurate tests
for the diagnosis of tuberculosis in orang-utans.
A study of the serological prevalence of a number of viral infections in captive orangutans
showed evidence of exposure to hepatitis B virus (42.6%), hepatitis A virus
(34.9%), herpes simplex viruses (14.7%), simian D-type retroviruses (11.2%) and
human T-lymphotrogic viruses (1.4%). There was no evidence of exposure to simian or
human immunodeficiency viruses.
Molecular studies to determine the origin of the hepatitis B virus, showed the virus was
not of human origin as has been generally assumed, but was an indigenous virus which
also occurred naturally in wild populations. The virus was subsequently named Orangutan
Hepadnavirus.
A molecular study using mitochondrial DNA was undertaken to determine whether
there was significant genetic diversity between six isolated populations of wild orangutans
within Borneo. It was concluded that there are at least four genetically distinct
populations located in East Kalimantan, southwest Kalirnantdcentral Kalirnantan,
northwest KalimantdSarawak, and Sabah.
The findings of this research are discussed in terms of the implications for management
policies for reintroduction centres, as well as for the conservation of wild populations.
They will also be of relevance to zoos and primate centres.
|
78 |
Survival rate estimates of Florida manatees (Trichechus manatus latirostris) using carcass recovery dataSchwarz, Lisa Kimberley. January 2007 (has links) (PDF)
Thesis (Ph. D.)--Montana State University--Bozeman, 2007. / Chairperson, Graduate Committee: Daniel Goodman. Includes bibliographical references (leaves 124-144).
|
79 |
Public perception of mammals and mammal conservation in Fairfax County, VirginiaWong, Dorothy L. January 2009 (has links)
Thesis (M.S.)--George Mason University, 2009. / Vita: p. 160. Thesis director: E.C.M. Parsons. Submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Science and Policy. Title from PDF t.p. (viewed Oct. 11, 2009). Includes bibliographical references (p. 152-159). Also issued in print.
|
80 |
Influence of a three-week wildlife education curriculum on knowledge and attitudes of South Carolina's Marlboro County High School ninth and tenth-grade biology studentsKrishon, Diane M., January 2004 (has links)
Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vii, 68 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 40-42).
|
Page generated in 0.1365 seconds