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The causes and consequences of population declines of two boreal forest species:the case of the willow tit (<em>Parus montanus</em>) and the Siberian flying squirrel (<em>Pteromys volans</em>)Lampila, S. (Satu) 08 April 2009 (has links)
Abstract
I used individual-based capture-mark-recapture data and genetic markers to gain understanding of the demographic and genetic processes operating in small and declining populations of two different species, the willow tit Parus montanus and the Siberian flying squirrel Pteromys volans. Both species have declined in Finland and the flying squirrel has been considered to be vulnerable. The willow tit study was conducted in northern Finland, near city of Oulu. The population size in the studied area has on average been stable during the past decade. Adult survival in the willow tit was high and fairly stable and was positively correlated with recruitment. Adult survival has been the most influential vital rate to the population growth rate. Local recruitment and immigration have high variation, inducing variation in the population growth rate. Female willow tits use extrapair copulations to maximise offspring heterozygosity. Heterozygous individuals are supposedly of higher quality than homozygous ones. I found weak negative association between individual homozygosity and recruitment probability. The flying squirrel populations have declined during the past ten years. Furthermore, adult survival has declined in one of the populations, most likely due to habitat loss and fragmentation that decrease the adult survival and limit dispersal. The flying squirrel populations were studied in western Finland. The flying squirrel densities in the studied areas are the highest in Finland and therefore these areas have been regarded as favourable for the flying squirrel. My results question this view. Microsatellite analyses strengthen the view of populations doing poorly, because the heterozygosities in all the populations and particularly in the most isolated one were rather low. High FST values indicate low dispersal even between adjacent populations. Following work should investigate the spatial variation in individual performance and the dispersal processes in these populations. For the flying squirrel it is vital to determine the size and quality of the patches that can support flying squirrels and the ones that apparently can not. Present estimates of survival and genetic diversity can be used to reconstruct a meaningful PVA and projections for these populations.
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Population ecology of bottlenose dolphins (Tursiops truncatus) off the east coast of ScotlandArso Civil, Mònica January 2015 (has links)
The population of bottlenose dolphins off the east coast of Scotland has been studied since the late 1980s, initially focused on the inner Moray Firth, where a Special Area of Conservation (SAC) was designated under the EU Habitats Directive. The population has since expanded its distributional range and currently ranges from the Moray Firth to the Firth of Forth. The main aims of this thesis were: (1) to estimate population parameters for this population using a 25 year individual recognition dataset, and (2) to increase knowledge of the distribution and abundance of dolphins in areas outside the SAC, especially to investigate areas of high use in St Andrews Bay. Apparent survival rate for adults and sub–adult dolphins was estimated at 0.946 (SE=0.005) accounting for temporary emigration caused by the population's range expansion. Sex-specific survival was estimated for males (0.951, SE=0.013) and females (0.956, SE=0.011) using multistate models to minimize bias caused by individuals of unknown sex. Using a newly developed approach, fecundity rate was estimated at 0.222 (95% CI=0.218-0.253) from an expected mean inter-birth interval of 4.49 yrs (95% CI=3.94-4.93). Total population size was estimated as ~200 individuals, after accounting for temporary emigration and for heterogeneity in capture probabilities. In St Andrews Bay, an area used regularly in summer by approximately half the estimated population, habitat use modelling identified the entrance to the Firth of Tay and waters around Montrose as high use areas for dolphins, whose presence was influenced by tidal current speed and direction. The results suggest that the conservation and management plan for this small and isolated population of bottlenose dolphins should be reviewed to adapt it to current knowledge, especially regarding the uncertainty around the potential impacts of offshore renewable energy developments off the east coast of Scotland.
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Beyond the Beach: Population Trends and Foraging Site Selection of a Florida Loggerhead Nesting AssemblagePhillips, Katrina 04 May 2011 (has links)
A twenty year mark-recapture dataset from the loggerhead nesting beach on Keewaydin Island, off the southwest coast of Florida, was analyzed using a two-state open robust design model in Program MARK to provide insight into recent nesting declines in the state. A total of 2,292 encounters representing 841 individual tag IDs were used for this analysis. Survival was estimated at 0.73 (95% CI 0.69-0.76), and there was no evidence from remigration rate or clutch frequency to suggest the composition of the nesting assemblage had changed over time. The mark-recapture analysis was supplemented with a satellite tracking component to identify the offshore foraging areas utilized by Keewaydin nesters. Eleven nesting females were outfitted with platform terminal transmitters, which transmitted for 42 to 300+ days including inter-nesting intervals and subsequent migration to foraging grounds. Site fidelity tests and kernel density home range analyses were used to describe foraging habitats. Females foraging in the eastern Gulf of Mexico were within the recent 64 m bottom longline fishery restriction. Areas identified as important habitats during the remigration interval should be used to inform managers in creating targeted management strategies to aid population recovery without the use of broad fishery closures.
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The interactive effects of climate, social structure, and life history on the population dynamics of hoary marmots (Marmota caligata)Patil, Vijay Unknown Date
No description available.
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Seasonal migration and reproductive behaviour of the Common River Frog (Amietia quecketti) / Joanita ViviersViviers, Joanita January 2013 (has links)
The Common River Frog Amietia quecketti is a well-known and widely distributed species in southern Africa. Despite the fact that it is a common species and quite prevalent in urban areas little is known about its behaviour. The North-West University Botanical Gardens was selected as study area as it supports a healthy population of Common River Frogs at a series of 18 water bodies. Each pond in the Garden was assigned a reference number and the surface area, depth and vegetation were noted. Frogs were located with the aid of strong flashlights. Specimens were caught by hand and transferred to clear plastic bags. Frogs were sexed and their mass and their snout-vent length (SVL) were determined. Frogs were subsequently individually marked by means of injecting a micro-transponder (pit-tag) subcutaneously.
Field observations were conducted over two consecutive evenings every two weeks for a period of one year. On the first night all sites were visited and all frogs were scanned and their position, orientation and activity were noted. During the second night focus was on Pond 6 as it sustained the biggest population. Observation started at 19:15 and continued until 02:30. All frogs in and around the pond were scanned and detailed notes were taken, focusing on their orientation, behaviour, calling activity and distance to the nearest other frog.
Results showed that limited movement between ponds in the Garden does occur. A number of individuals were recorded regularly. Some males had preferred call sites, and clear circadian and seasonal patterns with regards to males and females exist. The complex call structure consist of a chuck and a whine and then a combination of the two. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2013
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Seasonal migration and reproductive behaviour of the Common River Frog (Amietia quecketti) / Joanita ViviersViviers, Joanita January 2013 (has links)
The Common River Frog Amietia quecketti is a well-known and widely distributed species in southern Africa. Despite the fact that it is a common species and quite prevalent in urban areas little is known about its behaviour. The North-West University Botanical Gardens was selected as study area as it supports a healthy population of Common River Frogs at a series of 18 water bodies. Each pond in the Garden was assigned a reference number and the surface area, depth and vegetation were noted. Frogs were located with the aid of strong flashlights. Specimens were caught by hand and transferred to clear plastic bags. Frogs were sexed and their mass and their snout-vent length (SVL) were determined. Frogs were subsequently individually marked by means of injecting a micro-transponder (pit-tag) subcutaneously.
Field observations were conducted over two consecutive evenings every two weeks for a period of one year. On the first night all sites were visited and all frogs were scanned and their position, orientation and activity were noted. During the second night focus was on Pond 6 as it sustained the biggest population. Observation started at 19:15 and continued until 02:30. All frogs in and around the pond were scanned and detailed notes were taken, focusing on their orientation, behaviour, calling activity and distance to the nearest other frog.
Results showed that limited movement between ponds in the Garden does occur. A number of individuals were recorded regularly. Some males had preferred call sites, and clear circadian and seasonal patterns with regards to males and females exist. The complex call structure consist of a chuck and a whine and then a combination of the two. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2013
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The interactive effects of climate, social structure, and life history on the population dynamics of hoary marmots (Marmota caligata)Patil, Vijay 11 1900 (has links)
I used 8 years of mark-recapture data to test alternative hypotheses about the relative influence of winter climate, social structure, and life history on survival, reproduction, and population dynamics of hoary marmots (Marmota caligata) in the southwest Yukon. Climate, characterized by the mean winter Pacific Decadal Oscillation index (PDO), was strongly related to juvenile survival, more weakly linked with adult survival and fecundity, and did not appear to influence breeding probability. Group social structure had little influence on population dynamics. Variation in adult and juvenile survival affected the population growth rate more strongly than fecundity or breeding probability, but the relative influence of life history parameters changed from year to year. Comparisons between hoary marmots and other alpine mammals indicated that the average environment to which an animal is adapted, the strategies employed to survive winter, and life history constraints may all affect demographic sensitivity to winter climate. / Ecology
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The impact of fire on the honey possum Tarsipes rostratus in the Fitzgerald River National Park, Western Australiaaeveraardt@hotmail.com, Annika Everaardt January 2003 (has links)
The honey possum Tarsipes rostratus is a tiny (7 - 12 g) highly specialised flower-feeding marsupial endemic to the south-western corner of Australia. The impact of fire on this small mammal was studied, over a 19-year period, in the Fitzgerald River National Park, a large (330,000 ha) area of relatively undisturbed heathland/shrubland, rich in the proteaceous and myrtaceous plants upon which the honey possum appears to rely for food. The honey possum is the most abundant and widespread mammal in this Park.
Capture rates of honey possums were significantly related to the years since the vegetation was last burnt, annual rainfall in the preceding (but not the current) year, the season when trapping occurred, and the trapping grid operated. Capture rates declined markedly after fire and remained low (less than one third of those in long unburnt vegetation) for about 4 - 5 years following a fire. Rates of capture then increased steadily over the next 20 - 25 years, with maximal abundance recorded about 30 years after fire. Thereafter, there appeared to be a slight decline in capture rates, but even in the vegetation unburnt for longest (> 50 years since fire), honey possum abundance was substantial and relatively stable. In contrast to these changes in abundance, the structure of the honey possum population, with 79 % adults and 57 % males, appeared little influenced by fire history, annual rainfall, season or grid.
The increase in the rates of capture of honey possums following fire paralleled the pattern of availability of cover in the vertical and, to a lesser extent, horizontal plane. Indeed, projective foliage cover took around 20 years after fire to reach levels similar to those available in areas unburnt for even longer. The trend in capture rates was also congruent with the maturation of the most frequently visited foodplants of honey possums, particularly Banksia nutans (summer flowering) and B. baueri (winter flowering). Areas long unburnt still contained shelter and foodplants adequate for honey possums even 50 years or more after fire, with only slight evidence of senescence.
Pollen loads indicated that honey possums caught in burnt areas, where their preferred foodplants were absent, continued to feed on these favoured foodplants (Banksia and Dryandra spp.) at nearby unburnt areas. In addition, they also fed, in both burnt and long unburnt areas, upon a suite of other plant species that regenerated more rapidly from lignotubers and epicormic buds, as well as from seeds (e.g. Eucalyptus and Calothamnus spp.). Thus, honey possums appeared to persist with their preferences for feeding from a limited number of flowering plants despite some of these species not being available in recently burnt areas for many years. Nearby patches of unburnt vegetation can clearly be important refuges, feeding grounds and shelter for the few honey possums that visit recently burnt areas, and appear to be the source of honey possum colonists in the years following a fire.
Capture rates were also greater following years when rainfall was higher than average. Indeed, rainfall had as great an influence upon capture rates as time since fire. Capture rates were also consistently higher over winter, and to a lesser extent over summer, than in either autumn or spring. Individual grids, even those close together in apparently similar vegetation with a similar fire history, still differed significantly overall in their capture rates of honey possums. This last finding has implications for the use of chronosequences in the study of post-fire changes in biota.
Although not the primary focus of the study, data on the limited suite of other, far less abundant, small mammals present indicated that house mouse Mus musculus domesticus numbers peak soon after fire (about two years after fire), grey-bellied dunnart Sminthopsis griseoventer numbers somewhat later (about eight years after fire) and that southern bush rats Rattus fuscipes fiuscipes, like honey possums, are later successional species. Most species were present in vegetation over a range of post-fire ages, with data consistent with models based on sequential changes in relative abundance.
Like many Australian mammals, the range of the honey possum has contracted substantially over the last 200 years and the coastal heathlands of the south-west are its last stronghold. In terms of its conservation, this study indicates that, if possible, management burns in these heathlands should be separated by intervals of at least 20 years between successive burns, and preferably even longer. If burns are required more frequently to meet other management priorities, it is highly preferable that they are small and patchy, rather than large scale. Such practices may help ensure the long-term survival of this unique, highly specialised and endemic marsupial.
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Demography and dispersal ability of the Alpine Longhorn \kur{Rosalia alpina} (Coleoptera: Cerambycidae) / Demography and dispersal ability of the Alpine Longhorn \kur{Rosalia alpina} (Coleoptera: Cerambycidae)DRAG, Lukáš January 2011 (has links)
This Master Thesis brings results of study on endangered species Alpine Longhorn Rosalia alpina in beech forest of National Nature Reserve Maly and Velky Bezdez and Slatinne Hills. We used mark-recapture method to study the population size, longevity and dispersal ability of this species. We also assessed the distribution pattern of the species on another 15 habitat patches in the Ralska Upland.
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Improving the Computational Efficiency in Bayesian Fitting of Cormack-Jolly-Seber Models with Individual, Continuous, Time-Varying CovariatesBurchett, Woodrow 01 January 2017 (has links)
The extension of the CJS model to include individual, continuous, time-varying covariates relies on the estimation of covariate values on occasions on which individuals were not captured. Fitting this model in a Bayesian framework typically involves the implementation of a Markov chain Monte Carlo (MCMC) algorithm, such as a Gibbs sampler, to sample from the posterior distribution. For large data sets with many missing covariate values that must be estimated, this creates a computational issue, as each iteration of the MCMC algorithm requires sampling from the full conditional distributions of each missing covariate value. This dissertation examines two solutions to address this problem. First, I explore variational Bayesian algorithms, which derive inference from an approximation to the posterior distribution that can be fit quickly in many complex problems. Second, I consider an alternative approximation to the posterior distribution derived by truncating the individual capture histories in order to reduce the number of missing covariates that must be updated during the MCMC sampling algorithm. In both cases, the increased computational efficiency comes at the cost of producing approximate inferences. The variational Bayesian algorithms generally do not estimate the posterior variance very accurately and do not directly address the issues with estimating many missing covariate values. Meanwhile, the truncated CJS model provides a more significant improvement in computational efficiency while inflating the posterior variance as a result of discarding some of the data. Both approaches are evaluated via simulation studies and a large mark-recapture data set consisting of cliff swallow weights and capture histories.
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