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1187 Uppsatser om Habitat selection - Sida 1 av 80

Pre-spawning habitat selection of subarctic brown trout (Salmo trutta L.) in the river Vindelälven, Sweden

Habitat selection of migratory brown trout at the upper reaches of River Vindelälven, wasstudied in September during the pre-spawning period. The fish migrate from down- orupriver lakes for spawning in the river and data was collected by habitat mapping andradio-telemetry. Habitat selection of fish was analysed with preference curves andstatistical modelling, using the physical variables; depth, stream velocity and streambedsubstrate. Preference curves were derived by comparing fish habitat use with their nearbyavailable environment while the statistical modelling aimed to answer three main questions.1) Do the trout have a specific preference of depth, water velocity and streambed substrate?2) Is there any difference in Habitat selection between sexes? 3) Is there a shift in habitatselection over time? The preference curves indicated that trout favored water depths of 1-2m, velocity compositions characterized as glides (c.

Neonate mortality in fallow deer (Dama dama) in relation to bed-site selection and habitat use

The level of neonate mortality in a free ranging fallow deer (Dama dama) population at the Koberg estate in south western Sweden was investigated using radio-tracking techniques. During this study a total of 36 fawns (17 ?, 19 ?) were captured and marked with vhf or gps radio collars; 12 fawns in 2008 and 24 fawns in 2009. The neonate mortality calculated by the Kaplan-Meier method was 23.6 % and the mortality caused by predation was low, since only 1 of 8 non-surviving fawns died from predation by red fox (Vulpes vulpes). The spatial behavior of the fallow deer neonates were examined at two different levels i.e.

Selection of habitat and resources during migration by a large mammal : a case study of moose in northern Sweden

Migration is a worldwide phenomenon that has occurred for thousands of years in a vast variety of species. The general knowledge of migrating animals is poor even though billions of animals from a range of different groups migrate every year. The human impact on migrating ungulates is high and many populations are declining globally due to direct and indirect causes. Hence it becomes vital to study the migration phase and the habitat and resources selected during migration. The objective with this study was to identify the habitat characteristics and resource selection of moose during migration and compare the selection between different seasons and utilization distribution (relative frequency distribution for the points of location of an animal over a period of time) categories.

The influence of forestry stands treatments on brown bears (Ursus arctos) habitat selection in Sweden ? an option for Alberta forestry?

The brown bear population in Alberta, Canada has been decreasing, while the Swedish has been increasing and all the affecting parameters are not known. This study examined the difference in these populations to see if an explanation could be found in differences between the forest management. The aim of the paper was to see if stand treatments had an influence of brown bears Habitat selection in autumn in Sweden and how the results can be used in Alberta. This was done by analyzing bear positions in Sweden with forest data, and comparing forest management data for the study area in Sweden with forest management data for Alberta. The results displayed that mature forests over 60 years that have been commercially thinned are selected by bears rather than forests over 60 years that have not been commercially thinned in.

Spawning site selection of brown trout in habitat restored streams

During the timber floating era, most of Sweden?s watercourses were altered. This decreased the amount of available spawning habitats for salmonids, and hence had a negative effect on the riverine brown trout (Salmo trutta) populations. Reconstruction of spawning grounds is today a common measure in restoration of altered streams in Sweden. However, very little evaluation of the effectiveness of these reconstructed spawning grounds exists.

Flottledsåterställning i norra Sverige: : effekter på habitatkvalitet och populationstätheter av juvenil öringar (Salmo trutta L.)

In an effort to evaluate the effects of restorations of float ways on population density of stream dwelling fish in relation to the changes in habitat, I studied the physical habitat restored and channalized sites and their population density of brown trout (Salmo trutta L.) in three streams in the municipality of Sorsele. The differences between the channalized and the restored sites where most noticeable regarding substrate which where generally coarser in the restored sites. The analyses showed that the proportion of habitat that where suitable to the age class 0+ where significantly lower in the restored sites compared to the channalized sites. Regarding age class ?2+, no statistical differences in habitat quality were found.

Squatting i Alexandra : Om illegal bosättning i Sydafrika och hur landets bostadspolitik påverkats av Habitat II

Squatting innebär att människor illegalt bosätter sig på mark eller ockuperar tomma hus för att ha någonstans att bo. I samband med att världens storstäder växer, växer även squattingområden. För att förbättra situationen för bland annat squatters, hölls 1996 en FN-konferens, Habitat II.Syftet med uppsatsen är att belysa problemet med squatting och undersöker om Habitat II:s beslut haft någon inverkan på det deltagande landet Sydafrika. Den teoretiska ansatsen är realism och managerialism, där man menar att bostadssegregation beror på sociala och rumsliga hinder, samt att det är de med makt som ansvarar för bostadsituationen. De dokument från Habitat II har studerats som berör squatters samt sydafrikanska bostadspolitiska dokument.

Fåglar i urbana miljöer : kvaliteten på urbana habitat och om beståndstäthet är ett bra mått på habitatkvalitet

The urbanization of the world is increasing. How it affects bird populations have been well studied during the last decade, and comparisons between urban and non-urban habitats have been carried out. A common method for measuring habitat quality is to calculate the population density. This method is easy to use, but have been criticized during the last couple of years. In this study, data of population densities was compared with data on reproduction success.

En undersökning av Bergvik skogs och Skogsstyrelsens gallringsmallar mot en gallringsoptimering på simulerade typbestånd

The purpose of this study was to analyze the two thinning models: Bergvik Skog´s thinning model, which is based on total stems and dominant height, And Swedish forest agency´s thinning model which is based on basal area, habitat index, dominant height and recommended number of stems at final felling in Heureka´s StandWise and PlanWise. The data we chosen for our study were taken from the Swedish National Forest Inventory and we were creating a simulated stand based on a great number of sample plots in Region three from The Swedish National Forest Inventory. We had chosen to create one stand with low habitat index (T20) and one with high habitat index (T24). Our purpose were to come as close as possible to a natural stand in central Sweden. We performed the thinning in StandWise and analyzed the data I Excel files. Our thinning optimizing´s were performed and analyzed in PlanWise. There wasn´t any big differences between the thinning on the lower habitat index.

Habitat diversity and composition among growing wild boar (Sus scrofa L.) populations in Sweden

The wild boar (Sus scrofa L.) has expanded across Europe and Sweden in the last decades. It is a generalist species which utilizes a variety of habitats, and its presence has been shown to have both positive and negative effects for people and the landscape they are in. The abundance and increase of wild boar has previously been shown to differ between counties in Sweden, but there have been few explanations as to why. In this study, I investigated correlations between the per capita rate of change (r) among wild boar populations in Sweden and a variety of different habitats on the county level. I also investigated if fragmentation per se or in certain habitats could be associated with the wild boar?s per capita rate of change. My results show that fragmentation/diversity per se was not correlated with wild boar r.

Influence of the habitat on the potential for cannibalism and population dynamics in stream-dwelling European grayling (Thymallus thymallus L.)

Cannibalism can have major influence on fish population dynamics. A prerequisite for cannibalism is that the cannibal and the potential victim meet, and besides density effects, the encounter rate between cannibals and their victims is therefore also largely dependent on habitat use and habitat heterogeneity. In this study I quantified and compared the potential for cannibalism in stream-dwelling European grayling populations in three rivers in Jämtland by means of habitat classifications. I also analyzed population dynamic consequences of varying the potential for cannibalism in terms of intensity, using a physiological structured population model. Findings based on habitat characteristics were that the potential for cannibalism is in general not favourable in these types of streams.

Foraging and anti-predation behavior of Thomson?s gazelles (Gazella thomsoni) and Grant?s gazelles (Gazella granti) at a waterhole

Prey species make behavioral decisions to reduce the perceived risk of predation and the time spent vulnerable to predation. Behavioral responses to predators are for example selection of specific habitat types and the presence of predators influence individual vigilance. Furthermore, there is a variation in feeding niches with different herbivores focusing their foraging effort on different vegetation types which is also expected to affect the choice of habitat. Behavioral data on anti-predation and foraging behavior at on waterhole is collected from Thomson?s and Grant?s gazelles at Ol Pejeta Conservancy (0°00?N, 36°56?E) located in semiarid bushed grassland in Laikipia district of central Kenya.

Habitat selection of the European bison

Skogens konung eller präriens prins: var hör visenten hemma egentligen? Visenten är Europas tyngsta nu levande landdjur. Då en vuxen tjur kan nå nästan två meter i mankhöjd och väga upp mot ett ton så är det sannerligen en uppseendeväckande best. Trots detta är den relativt okänd: många jag talat med har varit omedvetna om existensen av denna art. Av dom som känt till den har flera haft föreställningen om att den är utdöd, eller blandat ihop den med antingen uroxen eller myskoxen.

Habitatmanipulering, en tveeggad bekämpningsmetod? : potentiella möjligheter och risker med alternativa födoresurser och skyddande habitat

Bevarande biologisk bekämpning är en bekämpningsstrategi som används för att bevara eller öka mängden av en specifik naturlig fiende till den skadeorganism som ska bekämpas. En skillnad i jämförelse med andra strategier inom biologisk bekämpning är att inga biologiska bekämpningsorganismer tillförs, i stället främjas de naturliga fiender som redan finns i odlingen och det omgivande landskapet. Habitatmanipulering är en metod inom bevarande biologisk bekämpning som bygger på en förändring av de naturliga fiendernas habitat som skall resultera i en förbättrad tillgång av nödvändiga resurser så som alternativ föda, skyddande habitat och alternativa bytes- och värddjur. Den här litteraturstudien undersöker potentiella möjligheter och risker med två metoder inom habitatmanipulering. Den ena metoden bygger på att inkludera blommande växter i en odling för att skapa en förbättrad tillgång av alternativa födoresurser, så som pollen och nektar, till naturliga fiender.

Internetbaserad rekrytering: mål, möjligheter och praktiker : En fallstudie av urvalet vid rekryteringen av sommarvikarier i Luleå kommun

The purpose of this study is to examine web-based recruitment to short term summer jobs at the SocialServices Department in Luleå municipality in Sweden. Recruitment goals, selection options on therecruitment homepage Offentliga Jobb and recruitment practices were analysed in order to reach a deeperunderstanding of the interactions between these three levels in the selection process. Pre-selection throughOffentliga Jobb was a special concern of the study. Different consciousness levels in the selection process areemphasised according to Anthony Giddens' structuration theory. Ten recruiters from different parts of thedepartment were interviewed.

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