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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.
41

Studies of the ecology of the East African buffalo

Sinclair, Anthony Ronald Entrican January 1970 (has links)
No description available.
42

Population Dynamics of Small Mammals in two Plant Communities of the Merritt Island National Wildlife Refuge

Goldberg, Jeffrey A. 01 April 1980 (has links) (PDF)
No description available.
43

Ecology of mule deer on the Pinon Canyon Maneuver Site, Colorado

Gerlach, Thomas P. 07 February 2013 (has links)
Mule deer (<i>Odocoileus hemionus</i>) population dynamics, movements, and habitat use were studied on the Pinon Canyon Maneuver Site in southeastern Colorado during January 1983-December 1984. Thirty-eight adults and 28 fawns were radio collared, and 35 adults were color collared or ear tagged. Population estimates were 365 and 370 deer for 1983 and 1984, respectively. The sex ratio (yearling and adult) was 60 males: 100 females. Adult female pregnancy rate was 95%; the mean litter size for females over 1.5 years was 1.7 fawns. Annual fawn survival was 29% in 1983 and 22% in 1984. Coyote (<i>Canis Iatram</i>) predation was responsible for 76% of fawn mortality. Adult survival was 88% in 1983 and 87% in 1984; coyote predation accounted for 67%, and hunting for 33% of the annual adult mortality. The calculated annual rate of increase (λ) was 1.01, indicating a stable population. Seasonal home range size differed (p < 0.05) between males and females only in the fall. Females preferred pinyon-juniper woodland in all seasons, and shrub grassland in winter, summer and fall; proportional use of woodland/open grassland and shrub/open grassland edge was greater than proportional availability. Males preferred pinyon-juniper woodland and avoided open grassland in all seasons. Fawns preferred shrub grassland and shrub/open grassland edge; they avoided cholla/open grassland edge. Fawns selected bed sites with greater (P < 0.05) concealment cover at all 0.5 m intervals up to 2 m in height, and greater ground cover of trees, shrubs, and grasses (P < 0.01) than random sites. / Master of Science
44

Small mammal communities at high altitude within the Sneeuberg Mountain complex, Eastern Cape Province, South Africa

Kok, Armand du Preez January 2012 (has links)
Due to their widespread and specious nature, small mammals are ideal for biogeographical studies. Small mammals also effectively connect various trophic levels by being both consumers and prey items for other animals. The Great Escarpment is the dominant mountain landscape in South Africa. Yet, very little small mammal research has been conducted on the Great Escarpment outside of the Main Drakensberg Mountains. This is surprising given the importance of mountains in shaping regional ecology. In this study, I assessed the diversity and community composition of small mammals at three high altitude (>1700m) sites within the Sneeuberg Mountain Complex (SMC) from June 2009 to May 2010. I also tested the effectiveness of five different bait types for measuring small mammal diversity (i.e. number of individuals caught, species richness, Shannon diversity index and Simpson index of diversity). Out of a total of 423 captures, 292 individuals of 12 small mammal species (one shrew, one elephant shrew and 10 rodents) were recorded over 5280 trap nights. The species richness and diversity of small mammals captured at the three sites were similar and this homogeneity was probably related to the regional processes (e.g. climate and latitude) that govern species richness and diversity. The most effective bait type in terms of capture success, species richness and diversity measurements was peanut butter and oats. In addition, the use of richness estimators revealed that peanut butter and oats was the most effective bait for sampling the species richness of small mammals. The effectiveness of peanut butter and oats was related to this bait having a more attractive scent, when compared to the other bait types. Future studies should focus on researching the range of local and regional processes that drive small mammal diversity at high altitudes in South Africa. I also recommend the use of more than one bait type when planning to survey small mammal communities.
45

A generalized stochastic birth/death population model based on Indian RiverLagoon dolphins

Unknown Date (has links)
For over a decade, researchers at Harbor Branch Oceanographic Institute (HBOI) have conducted surveys of the bottlenose dolphin (Tursiops truncatus) population of Indian River Lagoon (IRL) in Florida. I have constructed a 4-stage population model using the statistical program R. The model is used to conduct a viability analysis by analyzing the relationship between birth, calf and adult survival rates. The power analysis compares survey frequency to expected confidence intervals in estimating abundance. The sensitivity analysis shows that the population is most sensitive to changes in adult survival, followed by birth rate and calf survival. The model shows a strong chance of viability over a 50 year time span. The population is vulnerable to long periods of decline if birth, calf or adult survival rates fall below certain thresholds. Overall, the model simulates the future impacts of demographic change, providing a tool for conservation efforts. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
46

Ecological and socio-economic effects of industrial oil palm plantations in Southwest Cameroon

Kupsch, Denis 30 September 2019 (has links)
No description available.
47

The statistics of helicopter total counts of large ungulates in sourish mixed bushveld, northwest arid bushveld and mopane veld, Republic of South Africa

Reilly, Brian Kevin 12 1900 (has links)
Dissertation (PhD)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The use of helicopters has become almost universally accepted as the method of choice in the enumeration of large ungulates in Southern Africa. In most cases decisions affecting management of these populations are made based on a single count result. In all these instances the within technique variance is ignored, often leading to decisions based on type I or type II statistical errors where the within technique variance is misconstrued as the population change. Many studies have investigated the issue of accuracy of counting methods and a few have quoted precision values for various methods. Very few have, however, investigated power and those extant have approached the problem from a prospective point of view and predicted power values. This study has made use of replicated counts from 12 sites of the original 23 in four vegetation types of the then Transvaal Province. The study sites vary in terms of size and all counts were undertaken with an experienced, trained team in which only four observers were used. A comprehensive post hoc analysis of the results of the field surveys shows precision and power to vary widely according to species and vegetation type and concludes that gamecounting results are largely site specific. A decline in observations during the course of four hours of survey is demonstrated and although the exact cause cannot be determined, correction factors have been constructed for two vegetation types. Observers are shown to differ from one another in observation profile during the course of surveys. This study demonstrates, describes and quantifies the existence of several phenomena suspected to exist by experienced game counters, biologists and wildlife managers and makes proposals in terms of improving the data returned from expensive aerial surveys. / AFRIKAANSE OPSOMMING: In Suider-Afrika word die gebruik van 'n helikopter vir die tel van hoefdiere byna algemeen aanvaar as die metode wat voorkeur geniet. In meeste gevalle word besluitnemings rakende die bestuur van hierdie populasies gebaseer op die resultate van 'n enkele telling. In al die gevalle word tegniekverwante afwykings buite rekening gelaat en dit het die gevolg dat bestuursbesluite gebaseer word op tipe I en tipe II statistiese foute, en dit lei weer op hulle beurt dat tegniekverwante afwykings verkeerdelik geïnterpreteer word as die rede vir veranderings in die bevolkings. Verskeie studies het al die feitegeskil omtrent die akkuraatheid van telmetodes ondersoek en sommige het herhaalbaarheidswaardes vir die verskillende metodes aangehaal. Baie min het egter statistiese mag ondersoek en die wat dit wel gedoen het, het prospektiewe magsanalise as uitgangspunt gebruik en statistiese magwaardes voorspelom die probleem aan te spreek. Hierdie studie het gebruik gemaak van herhaalde tellings van 12 gebiede uit die oorspronklike 23 in vier veldtipes geleë in die ou Transvaal Provinsie. Die studiegebiede verskil in groottes. Alle tellings is deur 'n bekwaamde opgeleide span gedoen wat slegs vier waarnemers ingesluit het. 'n Omvattende post hoc analise van die resultate van die veldopnames dui aan dat herhaalbaarheid en statistiese mag baie varieer met betrekking tot spesies en veldtipes en word die gevolgtrekking gemaak dat wildtellingsresultate grootliks gebiedsgebonde is. In Afname in waarnemings gedurende die verloop van In vier uuropname, is waargeneem en alhoewel die ware oorsaak nie vasgestel kan word nie, is korreksiefaktore bereken vir twee veldtipes. Dit blyk dat waarnemers van mekaar verskil het met betrekking tot hul waarnemingsprofiele gedurende die verloop van die opnames. Hierdie studie dui aan, beskryf en kwantifiseer die bestaan van verskeie verskynsels wat vermoedelik bestaan het by ervare wildtelIers, bioloë en wildlewebestuurders en maak voorstelle met betrekking tot die verbetering van data wat tydens duur lugopnames ingesamel word.
48

Estimating abundance of rare, small mammals : a case study of the Key Largo woodrat (Neotoma floridana smalli)

Potts, Joanne M. January 2011 (has links)
Estimates of animal abundance or density are fundamental quantities in ecology and conservation, but for many species such as rare, small mammals, obtaining robust estimates is problematic. In this thesis, I combine elements of two standard abundance estimation methods, capture-recapture and distance sampling, to develop a method called trapping point transects (TPT). In TPT, a "detection function", g(r) (i.e. the probability of capturing an animal, given it is r m from a trap when the trap is set) is estimated using a subset of animals whose locations are known prior to traps being set. Generalised linear models are used to estimate the detection function, and the model can be extended to include random effects to allow for heterogeneity in capture probabilities. Standard point transect methods are modified to estimate abundance. Two abundance estimators are available. The first estimator is based on the reciprocal of the expected probability of detecting an animal, ^P, where the expectation is over r; whereas the second estimator is the expectation of the reciprocal of ^P. Performance of the TPT method under various sampling efforts and underlying true detection probabilities of individuals in the population was investigated in a simulation study. When underlying probability of detection was high (g(0) = 0:88) and between-individual variation was small, survey effort could be surprisingly low (c. 510 trap nights) to yield low bias (c. 4%) in the two estimators; but under certain situations, the second estimator can be extremely biased. Uncertainty and relative bias in population estimates increased with decreasing detectability and increasing between-individual variation. Abundance of the Key Largo woodrat (Neotoma floridana smalli), an endangered rodent with a restricted geographic range, was estimated using TPT. The TPT method compared well to other viable methods (capture-recapture and spatially-explicit capture-recapture), in terms of both field practicality and cost. The TPT method may generally be useful in estimating animal abundance in trapping studies and variants of the TPT method are presented.
49

Monitoring European pine martens (Martes martes) in Scottish forested landscapes

Kubasiewicz, Laura M. January 2014 (has links)
Monitoring the distribution, abundance and demography of species is vital to ensure that conservation efforts are appropriate and effective. Monitoring enables evaluation of responses to natural or human disturbance, highlights the need for management interventions and enables these interventions to be assessed and refined. The methods used largely depend on the specific aim of monitoring and behaviour of the target species, as well as the time and spatial scale that monitoring is required to cover. The European pine marten (Martes martes) is one of few remaining mammalian predators native to the UK. Since persecution in the early 19th century resulted in their near extinction, pine martens have recovered part of their former range in Scotland. Their recent recovery and an overlap in territory with vulnerable prey species such as the capercaillie (Tetrao urogallus) make the collection of accurate baseline data and subsequent monitoring of population trends vital for conservation efforts. Faecal counts have traditionally been used to provide a relative measure of population density for pine marten. In most cases, absolute measures of population density require individual identification. Non-invasive genotyping can provide this information but the quality of DNA from these samples is often poor. Here, the process is refined for pine marten faeces (scats) and hair samples. DNA degradation increased significantly for scats exposed to rainfall, with the rate of DNA amplification success reduced by 38% over a 16 day period. Success rates for hair samples were higher when more hair follicles were included in the analysis. Population densities were estimated for three forests in Scotland using a robust combination of non-invasive genotyping of hair samples and spatially explicit capture recapture modelling. Population density estimates of 0.07 (95% CI 0.03 - 0.16) to 0.38 km-2 (95% CI 0.11 - 1.07) were obtained which are within the range of previous estimates for forests elsewhere in Scotland. The first attempt to quantify the relationship between traditional scat counts and home range size was then conducted; a significant negative correlation exists but only when population density is relatively low. Previous studies suggest that pine martens in Western Europe are less forest dependent than those in Eastern Europe. Results from this thesis support this, with populations at the highest density found at sites with intermediate forest cover. This tolerance of lower forest cover is also apparent in the diet. Despite a preference for Myodes voles in populations in Eastern Europe, those in Western Europe show a strong preference for Microtus voles as well as a higher level of frugivory. We assess the autumn diet of four populations in Scotland assess the effect of forest cover and sex on the diet. There was no evidence of differential consumption of Microtus voles or birds between the sexes. Our analysis shows that frugivory is influenced by forest fragmentation, with a 5-fold increase in the occurrence of fruit (from 2% to 10%) as forest cover increased from 4% to 47%. Diversionary feeding has been suggested as a management technique to reduce the depredation of capercaillie by pine martens. This thesis presents the first attempt to quantify the success and cost-efficacy of diversionary feeding for a range of problems (crop damage, threatened safety, livestock depredation) across 30 experimental trials. The strategy proved more effective when targeted towards food-limited populations, and when aiming to alleviate habitat damage or risks to human safety rather than depredation. A novel decision-making framework was developed to aid managers with the initial planning of the strategy and its subsequent implementation within an adaptive format. Further to this, the feasibility of using diversionary feeding with a view to reduce the depredation of capercaillie by pine martens was assessed. Questionnaire responses were collected from people who have provided food for pine martens throughout Scotland. A positive reaction to food was observed, with 58% of respondents reporting that initial visits occurred within one week of placement and 46% reporting that subsequent visits were received daily. These results suggest that diversionary feeding may be a viable option for pine marten management, although testing of its impact on capercaillie productivity would be required.
50

The role of seasonality, environmental correlates and edge effects on the diversity and abundance of small mammals in Afromontane forest patches, Eastern Cape, South Africa / Small mammal diversity and abundance and the effects of seasonality within and at the edge of fragmented Afromontane forests in the Eastern Cape, South Africa

Junkuhn, Kyle Peter January 2015 (has links)
The Eastern Cape contains the majority of the remaining forested areas in South Africa (95.8 percent Coastal forests and 47.6 percent Afromontane forests), however these occur in fragments. Due to the rapid rise in the human population and its needs, conversion of forests to agricultural land and the extraction of timber increases, natural vegetation are lost and this therefore leads to forests becoming fragmented into small forest patches. One of the main consequences of forest fragmentation is loss of contiguous habitat, which is the dominant threat to species globally as it negatively affects both species richness and genetic diversity. This research investigates the effects that forest fragmentation has on small mammal diversity and abundance. The study sampled small mammals in Southern Mistbelt Afromontane forest patches in the Eastern Cape. The first aim of this study was to identify which environmental variable, or combinations of variables, affect the diversity and abundance of small mammals in fragmented forest patches in the Eastern Cape during the austral summer. The second aim was to compare seasonal changes in small mammal diversity and abundance at a forest edge compared to the forest core at Beggars Bush, an Afromontane forest in the Eastern Cape, South Africa. To identify the environmental impacts that different forests have on small mammals, nine different forests were chosen in the Eastern Cape and sampled during the summer in 2013. These nine forests were: Fort Fordyce Forest, Thaba Ndoda Forest, Hogsback Forest, Dassie Kraans Forest, Langeni Forest, Burchell’s Reserve Forest, Maiden Dam Forest and Kagaberg Forest. At each site, three transects of 30 Sherman Traps each were used. Trapping periods within each forest patch lasted between three to five consecutive nights and traps were inspected once a day in the morning. Nine environmental variables were initially identified and after being tested for normality and colinearity, five variables were chosen. These variables were Altitude, Mean Annual Temperature, Gradient, Patch Size and Mean annual potential evaporation. The number of individuals captures and species richness were then incorporated as dependent variables for best subset multiple regression model selection using the Akaike Information Criterion (AIC). For the second aim, the same trapping methods were used when comparing seasonal changes to diversity and abundance within the forest core. However at the forest edge, due to the small size of the forest, only 20 Sherman traps were used in each transect with five traps (25 percent) placed in the grassland and 15 (75 percent) placed in the forest along each transect. This study was one of few to survey small mammal diversity and abundance in fragmented forests in the Eastern Cape. Gradient, patch size and mean annual potential evaporation were the variables that best predicted the individual number of small mammal captures while only gradient best explained species richness. It does however, need to be noted that capture rates and species richness were very low and this would therefore effect the analysis of environmental variables. Future studies should have a larger sample size of forest patches and include more microhabitat environmental variables to determine their effects on small mammal diversity and abundance. However, it should be noted that through climatic extinction filtering, forest mammals are resilient generalists that can tolerate fragmentation effects. Furthermore, it was found that forest edges appear to play a significant role in small mammal diversity and abundance in the Beggars Bush Afromontane forest. Some species were habitat specialists such as Rhabdomys pumilio preferring the grassland habitat and Graphiurus murinus and Aethomys namaquensis the forest habitat, while Myosorex varius was the only species that was not habitat dependant. It was found that there was a greater diversity and abundance at the forest edge compared to within the forest core throughout most of the seasons. One possible flaw was that the sampling methods were different at the edge and within the forest and therefore future studies should ensure that the method stays uniform throughout the study.

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