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Klenzendorf, Sybille A. « Management of brown bears (Ursus arctos) in Europe ». Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/36807.
Texte intégralRésumé :
Successful conservation of brown bears (Ursus arctos) in Europe is associated with public acceptance of damages caused by bears. Recent increases in sheep depredation and beehive damage in central Austria resulted in the deaths of two bears there. Since bear numbers are low in most European populations, alternatives to the elimination of problem bears associated with damage incidents must be sought. The events described above led to the formation of the Bear Management Group responsible for designing a management plan for Austria that will outline procedures for dealing with bear damage and conservation strategies.
This study provides an overview of the magnitude and seasonal patterns of brown bear damage in Romania, Italy, Slovenia, Norway, Sweden, and Austria. It also illustrates how bears are managed in European countries by comparing different management strategies for dealing with brown bear damage, describing how bear management is organized, determining which organizations are involved, and explaining which duties these fulfill.
Bear damage data were obtained from interviews with wildlife managers, hunters, and farmers in Romania, Italy, Slovenia, Norway, Sweden, and Austria, and from official records of their bear management agencies. Most damage incidents involved sheep and beehives in all countries. All countries offered a more or less well functioning damage compensation program to farmers. Conservation success, especially for small bear populations, seemed to be related to a good compensation program and reducing damage to livestock and property. Possible improvements of management strategies to reduce damage and increase conservation success in theses countries were discussed
The second part of this study was the assessment of the organizational structure of different bear management programs in Europe. Brown bear management in Europe included a broad spectrum of goals, ranging from no protection, to regulated hunting, to total protection. In each country, different organizations were involved in bear management, including private and governmental organizations. For each study country, I outlined which organizations were involved in bear management, determined if a management plan existed,described if and how hunting and damage compensation were structured, explained how each country dealt with problem bears, and finally, detailed what kind of management problems each country encountered. I tried to find management patterns for bear management in Europe, including advantages and disadvantages of each approach and their effectiveness within the countries they were applied. Methods included a content analysis of interviews with wildlife managers, farmers, and local people in each country.Results showed that two general types of management approaches could be identified. Romania, Sweden and Southern Slovenia took a conservationist approach, which was characterized by economic use of their bear population. All of these countries had viable bear populations. Romania and Southern Slovenia included an additional characteristic of feeding bears, which could be viewed as a utilitarian management scheme. The second management approach, which was classified as the preservationist approach, was observed in Norway, Italy, Northern Slovenia, and Austria. This management strategy was characterized by year-long protection of bears, low population numbers, and no feeding of bears.
Further results of management differences in problem bear management, damage compensation, public education, and effectiveness of management approaches were summarized. The study provides a reference on bear management strategies in Europe.Master of Science
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Corradini, Andrea. « Ecological connectivity in the Alpine anthropic matrix. Natural reserves and corridors for the conservation of brown bear in the Alps (ABC - AlpBearConnect) ». Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/321014.
Texte intégralRésumé :
Large carnivores are among the most challenging species to conserve in our modern and crowded world. Having large spatial requirements and living in low density, they generally require wide and relatively undisturbed areas. In Europe, one of the most anthropized areas of the planet, these needs must be fulfilled in a complex human-dominated landscape. The reintroduced brown bear population living in the Central Alps represents one of the most emblematic examples of a constrained carnivore: despite a steady population increase in the first few years after reintroduction, the population did not substantially expand its range, nor has the Alpine-Dinaric metapopulation been reestablished as envisioned. Although humans have lived in the Alps for centuries, little is known about their impact on the bear population. In other environments humans are known to function as a “super-predator” by changing habitats, competing for space, consuming resources, and harvesting, which alters the ecological niche of animals, especially large carnivores. This dissertation aims to evaluate this phenomenon by assessing the effects of human disturbance on brown bears in the Alps. Anthropogenic disturbance is generally assessed by structural proxies, such as infrastructure and land use, which overlook the impact of human presence. In the first Chapter, we developed the Cumulative Outdoor activity Index (COI) to derive anthropogenic disturbance using crowdsourced data by Strava and validated it with ground truth observations derived from a local camera trapping survey. The intensity of COI provided an effective measure of functional anthropogenic disturbance, and it outperformed all commonly-used proxies of structural disturbance in predicting bear habitat use. When displacement is not an option because of habitat limitations and social mechanisms, bear mobility may clash with human activity. During the moments of lowest mobility, such as resting periods, animals have decreased ability to cope with risky situations, and therefore the selection of suitable resting areas is crucial for the long-term survival of individuals. In the second Chapter, we measured multi-scale response to risk perception (i.e., COI) and resource proximity using bedding sites by GPS radio-collared adult brown bears in the Alps. To map resources across the study area, we developed a GIS-database combining spatial and non-spatial ecological information to map fruit availability. We observed that bears apply a security-food trade-off strategy, avoiding functional anthropogenic disturbance while in proximity to resources. In the third Chapter, we explicitly tested the effect of an abrupt interruption of human mobility during COVID-19 lockdown on bears’ use of ecological corridors. Using bear occurrences reported to local authorities during the recent COVID-19 outbreak, we observed that bears used human-dominated areas more frequently, approached more intensively hot spots for road crossing network, and used areas further from the population core areas more often than previous years, suggesting that connectivity increased with reduced human mobility. In a comparatively human-free system, for the fourth Chapter we used longitudinal morphometric data to analyze drivers of changes in body mass as part of an international collaboration with biologists studying the grizzly bear in the Greater Yellowstone Ecosystem. Specifically, we analyzed changes in lean body mass and fat percentage during years of major ecosystem perturbations. We observed that individual lean body mass during the last two decades was primarily associated with population density, but not body fat percentage, showing density-dependent factors. Our combined findings (Chapters 1-3) showed that brown bears have to adapt their space use, movement, and resource proximity as a result of functional anthropogenic disturbance. In Chapter 4 we explored one effect of unconstrained bear space use on individuals, as manifested through density-dependent effects on body size. In the Alps, however, we found multiple instances of the human-super predator outcompeting bears so as to make density-dependent effects likely less significant as compared to human-caused mortality. These effects could occur in a variety of socio-ecological contexts across Europe, jeopardizing the long-term establishment of both newly reintroduced bear populations, as well as spatially limiting those naturally present in the environment. In response to disturbance, bears have had to reduce their ecological niche in human-dominated landscapes. Allowing humans and bears to coexist in the same landscape is a challenging task, but it is essential for the long-term survival of this newly reintroduced population that are otherwise at risk of extinction.
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Hillesheim, Benjamin James. « Cranial Morphological Distinctiveness Between Ursus arctos and U. americanus ». Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etd/3261.
Texte intégralRésumé :
Despite being separated by millions of years of evolution, black bears (Ursus americanus) and brown bears (Ursus arctos) can be difficult to distinguish based on skeletal and dental material alone. Complicating matters, some Late Pleistocene U. americanus are significantly larger in size than their modern relatives, obscuring the identification of the two bears. In the past, fossil bears have been identified based on differences in dental morphology or size. This study used geometric morphometrics to look at overall differences in cranial shape and used step-wise discriminant analysis to identify specific characters that distinguish cranial morphology between black and brown bears. Such differences could prove important in identifying fossil bears when crania are present but teeth are missing. Furthermore, being able to properly identify U. arctos and U. americanus crania is important in understanding evolutionary and ecological distinctions among both fossil and modern bears. Principal components, discriminant, and thin plate spline analyses indicated a clear morphological separation between the crania of U. americanus and U. arctos and highlighted key identifying features including a more convex forehead and a narrower, more elongate rostrum in U. arctos than U. americanus.
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Virmaja, Tommy. « Skillnader i födoval mellan brunbjörnshonor (Ursus arctos) med och utan årsungar ». Thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-63608.
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Inom födosöksteori söker och konsumerar djur föda på ett sätt som maximerar deras förmåga att reproducera sig och få sina gener representerade i kommande generationer. För att åstadkomma detta måste individer ibland anpassa sina beteenden. Brunbjörnhonor (Ursus arctos) med årsungar måste bland annat dela den föda de hittar med ungarna. För att inte riskera att ungarna dödas av hannar så har honor med årsungar under parningsperioden mindre hemområden och rör sig mindre under ett dygn än vuxna honor utan årsungar. Med bakgrund av dessa olikheter undersöks ifall honor med årsungar konsumerar annan föda jämfört med honor i andra reproduktiva kategorier. En spillningsinsamling från GPS-märkta björnar gjordes i västra Hälsingland och norra Dalarna under 2015 från 25:e maj till 11:e oktober. Inför dataanalysen delades säsongen upp i två perioder vid den 15:e juli på grund av olikheter i födotillgång samt att parningssäsongen slutar. En frekvensanalys gjordes av individernas spillningar som resulterade i en icke signifikant skillnad mellan honor med och honor utan årsungars födoval. En undersökande dataanalys av volymprocent antyder dock att det kan finnas skillnader i mängd av vissa födoämnen under parningsperioden. Dessa skillnader fanns i kategorierna ben, älghår samt övriga växtmaterial. Även om studien lider av liten provstorlek med endast fyra honor med årsungar i var och en av de båda perioderna tycks undersökningen originell med en upplösning på individnivå. Tidigare skandinaviska födovalsanalyser hos brunbjörnen har gjorts med spillning som minsta enhet.According to foraging theory, animals seek and consume food in ways that maximize their ability to reproduce and have their genes represented in future generations. In order to achieve this, individuals must sometimes adapt their behaviors. Females of the brown bear (Ursus arctos) with cubs of the year must share the food they find with their cubs. To protect the cubs from being killed by males in the mating period, females with young have smaller home ranges than other adult females and move less on a daily basis than other females. In view of these differences my hypothesis is that females with yearlings consume different food items than other females. A fecal collection from GPS-marked brown bears was made in 2015 in the northern Dalarna county and northwestern county of Gävleborg in Sweden from 25 May to 11 October. Prior to the data analysis, the season was divided into two periods, 25 May to 15 July and 16 July to 11 October, based on differences in food availability and season (mating vs non-mating season). A frequency analysis detected no significant differences in food items consumed for either period. However, an exploratory data analysis of percent volume of different food items suggests that there may be differences in the amount of certain foods during the mating period. These differences were found for the food categories, bone, moose hair and other plant material. Although the study suffers from a small sample size with only four females with cubs of the year in each of the two periods, this study is relatively novel with a resolution at the individual level. Previous food item analyzes of the brown bear in Scandinavia have been done with fecal samples as the smallest unit.
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Kopatz, A. (Alexander). « Genetic structure of the brown bears (Ursus arctos) in Northern Europe ». Doctoral thesis, Oulun yliopisto, 2014. http://urn.fi/urn:isbn:9789526204307.
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Abstract Wild populations of large carnivores in Europe were almost wiped out during the last centuries. Nowadays, the number of brown bears in North and Eastern Europe has increased, and the current situation suggests that these populations have recovered or are in the process of recovery. Knowledge of the population genetic consequences of demographic recovery in large carnivores, especially across national borders and on broader geographical scales, is still limited. In this study, we collected 3,757 fecal and hair samples as well as 881 tissue samples from brown bears across Northern Europe, with a focus on the Finnish population and neighboring areas, to investigate the population structure, connectivity, and genetic diversity on a spatial as well as a temporal scale. Bayesian clustering analysis of the population structure suggested the division of brown bears in Northern Europe into several genetic clusters, and the subdivision of the Finnish population into a northern and southern subpopulation. The estimation of gene flow pointed to better connectivity of the bears between Southern Finland and Western Russia, while migration between Scandinavia and Northern Finland as well as between Scandinavia and Southern Finland/Western Russia appeared to be restricted. Genetic clusters identified in Finland, Russia and Northern Norway displayed high genetic diversity, which was among the highest reported in wild brown bears. Recovery of the Finnish population has been accompanied by a detected range expansion towards the north, while genetic differentiation between clusters has decreased and genetic diversity has increased in the southern population, suggesting expansion from the south. Our results demonstrated that the immigration of bears from Russia still plays a major role in the Finnish bear population; however, connectivity between the Finnish-Russian population and Scandinavian bears appears to be restricted and should be improved, as well as regularly monitoredTiivistelmä Suurpetojen luonnonpopulaatiot hävisivät Euroopasta melkein kokonaan viimeisten vuosisatojen aikana. Ruskeakarhujen määrä on viime aikoina kasvanut Pohjois- ja Itä-Euroopassa, ja karhupopulaatiot ovat toipuneet tai toipumassa. Tieto demografisen toipumisen geneettisistä seurauksista populaatioissa on varsin rajoittunutta etenkin laajemmassa maantieteellisessä mittakaavassa, yli valtiorajojen. Keräsimme tätä tutkimusta varten 3757 uloste- ja karvanäytettä ja 881 kudosnäytettä Suomesta ja sen lähialueilta. Tarkoituksenamme oli kartoittaa Pohjois-Euroopan karhupopulaatioiden geneettistä rakennetta ja monimuotoisuutta, sekä populaatioiden välisiä yhteyksiä huomioiden ajallinen ja maantieteellinen ulottuvuus. Bayesiläisen ryhmittelyanalyysin perusteella Pohjois-Euroopan karhut jakaantuvat useaan geneettiseen ryhmään. Suomen populaatiossa erottuivat eteläinen ja pohjoinen alapopulaatio. Analyysit geenivirran määrästä osoittivat, että Etelä-Suomen ja Länsi-Venäjän karhupopulaatiot ovat yhteneväisemmät, kun taas migraatio Skandinavian ja Pohjois-Suomen sekä Etelä-Suomen ja Länsi-Venäjän välillä vaikuttaisi olevan rajoittunutta. Suomesta, Venäjältä ja Pohjois-Norjasta tunnistetut alaryhmät olivat geneettisesti hyvin monimuotoisia, ja muuntelu oli korkeampaa kuin koskaan aiemmin karhuilla havaittu. Suomen karhupopulaation toipuessa ja levitessä pohjoiseen, geneettinen erilaistuminen maan sisällä on vähentynyt ja eteläisen alapopulaation monimuotoisuus kasvanut. Tämä viittaa populaation laajentumiseen etelästä käsin. Tulosten perusteella karhujen tulomuutto Venäjältä on yhä tärkeää Suomen populaatiolle. Suomen ja Venäjän karhupopulaatioiden yhteyttä Skandinavian karhupopulaatioihin tulisi seurata ja parantaa
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McCann, Robert Keith. « Activity measures of free-ranging grizzly bears (Ursus arctos) in the Flathead drainage ». Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30082.
Texte intégralRésumé :
Between 1984 and 1988, 4756 hours of activity data were collected on 15 different grizzly bears (Ursus arctos) in the Flathead drainage of southeastern British Columbia and adjacent portions of Montana. Data were collected with the aid of portable chart recorders that recorded the output from motion-sensitive radio collars. While many benefits stem from remote sensing of a study animal as intractable as the grizzly, both the method of data collection and the assumptions employed in translating chart recordings into quantitative measures of bear activity may affect conclusions drawn.
Major objectives of this study were: 1) to assess the validity of procedures employed to translate continuous chart recordings of signal patterns from motion-sensitive radio collars into quantitative measures of bear activity; 2) to assess whether active and inactive bout lengths were related to sex and age related differences in energetic requirements and seasonal differences in food type; and 3) to document activity budgets and patterns as functions of sex, age, season, and the daily solar cycle.
In the absence of concurrent visual observations of grizzly bears and recorded signal patterns, the validity of procedures used to interpret chart recordings was assessed by estimating percent of time active (%TA) under varying definitions of active and inactive bouts, and by comparing %TA to values found by other researchers. Estimates of %TA were stable over the range of activity bout definitions examined. Stability resulted from bears spending most of their time in active and inactive bouts > 30 min duration. Estimates of %TA for this study agreed with results on other populations. Over the non-denning portion of the year, grizzly bears were active about 55% of the time.
Analyses of bout durations were plagued by a bias against active bouts to be monitored in their entirety, because when active, bears frequently moved out of range of the chart recorder. The distribution of activity over the 24-hour cycle differed from many other studies in that bears in the Flathead were active mostly in daylight hours. A greater use of darkness by bears in the fall, compared to other seasons, may be related to available daylight or to avoidance of hunters. While activity patterns were generally bimodal with activity peaks in morning and evening, the morning activity peak was not strongly tied to sunrise. Activity in the morning generally reached a peak 1 or more hours after sunrise. Seasonal trends in activity budgets conformed to physiological changes in bears necessitated by requirements for denning. Significant individual variation exists in both activity patterns and budgets, and may be related to body size, to frequency dependent foraging strategies, or to differing competitive ability for defendable resources among sex-age classes of bears.Land and Food Systems, Faculty of
Graduate
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Bellemain, Eva. « Genetics of the scandinavian brown bear (Ursus arctos) : implications for biology and conservation ». Université Joseph Fourier (Grenoble), 2004. http://www.theses.fr/2004GRE10168.
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Cette thèse traite de 1'application de l'outil moléculaire, en combinaison avec les données de terrain, pour la gestion, la conservation et la compréhension de la biologie et du comportement de l'ours brun (Urslls areros) Scandinave. La première partie de cette thèse est une partie méthodologique, dans laquelle nous avons développé des aspects techniques en biologie moléculaire (notamment par la définition de protocoles d'amplification d'ADN à partir d'échantillons fécaux) et en analyse de parenté. La seconde partie concerne l'application de ces outils dans l'étude et la gestion des populations. Nous avons évalué plusieurs estimateurs de tai11e de population à partir soit d'un échantillonnage non invasif et de méthodes moléculaires, soit de méthodes de terrain traditionnelles, et déterminé que l'estimateur le plus fiable était celui du programme MARK, basé sur un principe de capturemarquagc-recapture à partir de données génétiques. La population d'ours brun en Suède a étéestimée à 2200 individus en 2004. Le système d'appariement de l'ours brun a été étudié en relation avec l'infanticide sexue11ement sélectionné (SSI), à partir des al:alyses de parentés. Le SSI serait une stratégie reproductive des mâles. Les femelles emploieraient des contrestratégies au SSI en s'accouplant avec plusieurs mâles afin cie confondre les paternités et avec les mâles 1es plus susceptibles de commettre l'infanticide. Les mâles les plus hétéroz. Ygotes et les plus gros seraient préférentiellement sélectionnés par les femelles, probab1ement p<1r un mécanismc post copulatifThis thesis deals with the application ofmo1ecular tools, combined with field data, in wildlife management, in conservation and in understanding biology and behavior of the Scandinavian brown bear (UrslIs arc/os). The first part of this thesis is a methodological part, in which we deve10ped or reviewed technical aspects in molecular biology (particularly, we defined protocols to ampli fy DNA from fecalsamples) and in parentage analysis; the second part is devoted to the application of molecular genetics for managing Populátions. We evaluated several population size estimators, either from non invasive sampling é1lldmolecular methods, or from traditional field methods, and determined that the most reliable estimator was the one from programm MARK, based on a capture-mark-recapture principle, from genetic data. The brown bear populationin sweden was estimated to be around 2200 individuals in 2004. The brown bear mating system was studied in relation with sexually selected infanticide (SSI), from parentage analyses studies. SSlmight be an adaptive male mating strategy. Fema1es might employ counter strategies such as multiple male-mating to confuse paternities and mating with future potentia11y infanticidalmales. Most heterozygous and leu'ger males would be preferentially selected by females, probably through a post copulatory mechanism
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Pigeon, Karine. « Plasticité comportementale de l’ours grizzli (Ursus arctos horribilis) dans un contexte de changements climatiques ». Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26065.
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L’étude de la plasticité comportementale s’attarde aux réponses physiologiques et comportementales des individus face aux contraintes de leur environnement. Les changements climatiques modifient les conditions du milieu et ont le potentiel d’influencer les composantes biodémographiques des individus. L’étude des liens mécanistiques entre le comportement animal et les conditions du milieu est donc utile à la compréhension des impacts potentiels des changements climatiques sur les individus. Le premier volet de ma thèse s’attarde aux liens entre les conditions du milieu, le comportement d’hibernation et la sélection de tanière de l’ours grizzli, une espèce menacée en Alberta. Ce volet révèle que l’abondance de nourriture à l’automne ainsi que le statut reproducteur des individus sont liés aux variations observées dans les dates d’entrée en tanière tandis que les conditions météorologiques à large échelle et le statut reproducteur des individus expliquent bien les dates de sorties de tanières. Ce volet démontre aussi que les caractéristiques physiques des tanières ne diffèrent pas entre les sexes et que pour creuser leurs tanières, les mâles et les femelles sélectionnent des attributs du paysage similaire. À large échelle, l’ours grizzli évite les zones humides et choisi des peuplements de conifères en haute altitude associés à une grande disponibilité de nourriture de haute qualité au printemps. À l’échelle du domaine vital et à l’échelle locale, l’ours grizzli choisi des peuplements de conifères associés à un fort couvert latéral et vertical, à une faible disponibilité de nourriture de haute qualité à l’automne, à une forte abondance d’Hedysarum spp. ainsi qu’à une faible densité de routes. Le second volet s’attarde à la sélection de l’habitat et à la thermorégulation durant la période active et mets en évidence les contraintes thermiques associées à une augmentation de la température ambiante sur les patrons de sélection de l’habitat. La sélection de l’habitat de l’ours grizzli selon les saisons et durant la journée dépendait de la température ambiante et ce, davantage pour les mâles que pour les femelles. Plus la température ambiante était élevée, plus la sélection de peuplements ouverts qui abondent en nourriture de haute qualité augmentait durant les périodes les plus fraîches de la journée et plus la sélection de ces mêmes peuplements diminuait durant les périodes les plus chaudes de la journée. Ma thèse approfondie les connaissances concernant les facteurs intrinsèques et extrinsèques influençant le comportement d’hibernation et met en évidence l’influence de la thermorégulation sur la sélection de l’habitat chez l’ours. Mes résultats contribuent à une meilleure compréhension des facteurs déterminant la distribution des individus et améliore notre capacité à prédire l’effet des changements climatiques globaux sur les grands mammifères.The study of behavioural plasticity aims at understanding the physiological and behavioural responses of individuals to limiting factors. Climate change has the potential to influence the life history of individuals by altering environmental conditions. Thus, studying the mechanistic links between animal behaviour and environmental conditions is necessary to understand the potential impacts of climate change on individuals. The first part of my thesis focuses on the links between environmental conditions, hibernation behaviour, and habitat selection of grizzly bears, a threatened species in Alberta, Canada. The phenology of den entry and exit was driven by sex and reproductive status, food availability in autumn, winter precipitation, and spring temperature. There was no difference in the dimensions and characteristics of dens excavated by male and female grizzly bears, and males and females selected similar landscape attributes to dig their dens. At the broadest scale investigated, grizzly bears avoided wetlands and selected high-elevation dry conifer stands with abundant high-quality spring foods. At the home-range scale and within the den vicinity, grizzly bears selected dense conifer stands associated with little high-quality autumn food and abundant Hedysarum spp. in areas with low road densities. The second part of my thesis focuses on the links between habitat selection and thermoregulation during the active season, and highlights the thermal constraints associated with increasing ambient temperatures on habitat selection patterns. Grizzly bear habitat selection followed a daily and seasonal pattern that was influenced by ambient temperature, with adult males showing a stronger response than females to warm temperatures. With increasing ambient temperatures, male and female grizzly bears increased their selection for open stands with abundant food resources during the coolest periods of the day, and concurrently decreased their selection for these open stands during the warmest periods of the day. My thesis increases our understanding of the role of intrinsic and extrinsic factors on hibernation behaviour, habitat selection, and thermoregulation constraints of grizzly bears. Ultimately, my results enhance our understanding of the factors regulating the distribution of individuals in time and space; improving our ability to predict the potential impacts of climate change on large mammals.
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Bogner, Emily, Blaine W. Schubert et Josh X. Samuels. « Differentiating Black Bears (Ursus americanus) and Brown Bears (Ursus arctos) Geographically using Linear Measurements of Teeth and Identification of Ursids from Oregon Caves National Monument ». Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/39.
Texte intégralRésumé :
North American black bears (U. americanus) and brown bears (U. arctos) can be difficult to distinguish in the fossil record due to similar dental and skeletal morphologies. Challenges identifying ursid material from Oregon Caves National Monument (ORCA) called for an accurate tool to distinguish the species. Ursid teeth have a high degree of variability and morphological features are not always diagnostic. This study utilized a large database of lower tooth lengths (p4, m1, m2, and m3) and ratios (p4/m1, m2/m1, m3/m1, p4/m3, m2/m3) in an attempt to differentiate U. americanus and U. arctos in North America. Further, this project examined how these linear measurements differ in response to ecoregion, latitude, and climate. Analysis of variance (ANOVA) found significant differences between U. americanus and U. arctos from across North America for every variable studied. Stepwise discriminant analyses (DA) found lengths separated species better than ratios with 99.1% correct classification versus 77.5% correct classification for ratios. When sexes were analyzed, ANOVA only found significant differences for lengths while DA found lengths and ratios could not accurately distinguish between sexes; only 72.1% of sexes were classified correctly while utilizing lengths and 61% for ratios. Seventeen previously identified fossil specimens from across North America, in addition to the ORCA specimen, demonstrated the utility of this study, confirming several identifications and rejecting others, proposing the need for new designations.
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Gonzalez, Ofelia. « Causes et conséquences de la variation en taille de portée chez l'ours brun (Ursus Arctos) ». Mémoire, Université de Sherbrooke, 2011. http://savoirs.usherbrooke.ca/handle/11143/4918.
Texte intégralRésumé :
La taille de portée est une composante importante de l'aptitude phénotypique d'un individu. La variabilité du nombre de jeunes produits parmi différentes espèces a souvent été explorée, mais peu d'études ont été en mesure d'approfondir le principe de compromis entre le nombre et la taille des jeunes de façon spécifique aux grands mammifères. Le suivi long terme des populations de mammifères de grande taille offre la possibilité de dissocier des petits mammifères les composantes de la variabilité en taille de portée ainsi que le compromis entre nombre et taille des jeunes. En ce sens, une réduction de la taille de portée par mortalité juvénile en nature permet la manipulation des portées chez les espèces expérimentalement difficile à étudier. L'objectif général de mon étude était d'analyser les causes et les conséquences de variation en taille de portée chez l'ours brun (Ursus arctos) en Scandinavie à l'aide d'une base de données de 24 années. Le premier objectif était d'identifier les facteurs occasionnant la variabilité en taille de portée. Le deuxième objectif était de quantifier l'impact des caractéristiques maternelles et du sexe ratio sur la masse des oursons d'un an, en prenant en compte les effets de la taille de portée. Finalement, j'ai exploré les conséquences de la réduction de la taille de portée par mortalité en termes de masse corporelle chez les oursons d'un an. Mes analyses ont révélées [i.e. révélé] que l'âge de la mère est en majeure partie responsable de la variation de la taille de portée. Les femelles les plus jeunes produisaient le moins d'oursons par portée et par conséquent engendraient les masses totales de portée les plus faibles. Par contre, la taille corporelle des mères expliquait davantage la variabilité de la masse des oursons d'un an, alors que le sexe ratio n'expliquait ni la taille de portée, ni la masse des oursons. Il semble donc que les déterminants de la taille de portée les plus souvent observés chez les petits mammifères n'aient pas tous la même importance chez les grands carnivores. En effet, ni la taille corporelle de la mère, ni les conditions environnementales traduites par l'indice NDVI n'ont pu expliquer la taille de portée chez l'ours brun. Seul l'effet de l'âge de la mère était cohérent avec les études de petits mammifères. Finalement, j'ai décelé un compromis entre le nombre et la masse des oursons d'un an, ainsi qu'une compétition au sein des portées. Effectivement, la masse des oursons d'un an était négativement reliée à la taille de portée et en plus, une réduction de la taille de portée favorisait le gain en masse des oursons survivants. Ce gain en masse observé chez l'ours brun, soit environ 7 à 8%, est d'un ordre semblable à celui retrouvé parmi plusieurs études de petits mammifères. Ces résultats sont d'un intérêt considérable en ce qui concerne l'étude de la variabilité en taille de portée qui s'avère fondamentale pour la compréhension des stratégies de reproduction chez différentes espèces. Ils pourront être potentiellement applicables aux espèces de grands mammifères pour lesquelles le suivi des reproductions est difficilement réalisable, ou encore aux espèces chez qui les infanticides jouent un rôle prédominant dans la mortalité des jeunes. En effet, l'utilisation de réductions naturelles de la taille de portée peut devenir un moyen intéressant d'évaluer différents coûts à la reproduction, spécialement chez les grands mammifères pour qui le nombre relativement faible de jeunes produits rend la compétition au sein des portées difficile à estimer.
11
Alvarez-Rodriguez, Manuel. « Mejora y evolución de los protocolos de congelación de eyaculados de oso pardo (Ursus arctos) ». Doctoral thesis, University of Leon, Facultad de Ciencias Biologicas y Ambientales, Spain, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-130203.
Texte intégralRésumé :
La situación crítica del oso pardo (Ursus arctos) en España plantea la necesidad de aplicar diferentes estrategias de conservación, dentro de las cuales tiene especial relevancia la creación de un banco de recursos genéticos. La eficacia de esta herramienta depende, entre otros factores, de la adaptación específica de los protocolos de congelación espermática ya existentes y que permitan el almacenamiento eficaz de los espermatozoides del oso pardo en un banco de germoplasma. Este trabajo nos permite concluir la utilidad de la selección entre ciclos con el fin de mejorar la calidad de los espermatozoides sometidos a recongelación
12
Ayache-Donat, Bernadette. « Croissance crânienne et éruption dentaire d'Ursus arctos (Mammalia, Carnivora) : application aux sites du Mont Ventoux (Brantes, Vaucluse) ». Aix-Marseille 2, 2003. http://www.theses.fr/2003AIX20665.
Texte intégralRésumé :
L'étude d'abondants restes crâniens et dentaires d'Ursus arctos découverts dans 4 cavités holocènes du Mont Ventoux (brantes, Vaucluse, France) a permis d'évaluer le nombre d'individus, de leur attribuer un âge, ou un sexe pour les adultes. 76 oursons, 8 juvéniles et 24 adultes, plus de femelles que de mâles, ont été identifiés. Les différences et l'évolution des os crâniens lors de la croissance ont été étudiés. Le développement entre 4 moi et le stade adulte n'est pas uniforme. Le crâne s'allonge, plus particulièrement au niveau de la face et ne s'élargit que très peu, la largeur du neurocrâne s'effectuant rapidement. C'est à partir du stade juvénile que se développent le museau et l'arrière crâne. L'examen des dents et de leurs alvéoles a permis de préciser le nombre de générations des prémolaires antérieures à la P4 et d'établir la formule dentaire suivante :I1 I2 I3 C d1 (P2) P3 M1 M2 et I1 I2 I3 C d1 (P2) (P3) M1 M2 M3. La comparaison des Ours bruns du Mont Ventoux avec les populations fossiles et actuelles montre qu'ils étaient nettement plus grands que ceux des Pyrénées et de l'Italie mais plus petits que les Ours bruns du Pléistocène ou de l'Europe centrale.
13
Gregório, Inês de Sousa. « Genetic structure, diversity and gene flow on a threarened population of brown bear (Ursus arctos) in Cantabria, Spain ». Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22700.
Texte intégralRésumé :
Mestrado em Ecologia AplicadaAo longo de vários séculos, a distribuição geográfica do urso pardo na Península Ibérica tem vindo a diminuir, estando de momento limitada ao norte de Espanha. A população de urso pardo da Cantábria é uma das mais pequenas da Europa e está dividida em duas subpopulações (Ocidental e Oriental), com conectividade limitada entre ambas. Para além disso, a perseguição, por parte das populações humanas, apresenta sérias ameaças à sobrevivência da população de urso pardo na Cantábria. Tendo em consideração a situação atual da população Cantábrica, é essencial ter uma imagem muito clara dos padrões genéticos da população. Foram usados três tipos de marcadores genéticos (ADN mitocondrial, microssatélites nucleares autossómicos e marcadores sexuais) para inferir a origem, estrutura e diversidade genética e fluxo genético da população. Os resultados aqui apresentados sugerem que a população Cantábrica está dividida em duas linhagens matrilineares distintas e que não é monofilética relativamente a outras populações europeias. Esta diferenciação, num eixo oriental-ocidental, poderá estar relacionada com eventos de colonização da cordilheira Cantábrica anteriores e contemporâneos ao último máximo glaciar. A população está estruturada em duas subpopulações com grande diferenciação genética entre as duas. Os resultados mostram fortes evidências de migração de ursos entre as duas subpopulações. Nomeadamente, encontramos evidências da existência de fluxo genético assimétrico e de maior fluxo recente de migrantes da subpopulação Oriental para a Ocidental. Contudo, os resultados sugerem uma maior introgressão recente em sentido contrário. Este estudo ajuda a clarificar as origens da população e fornece novo conhecimento sobre a condição genética e os padrões de migração e fluxo genético da população de urso pardo. Os resultados aqui apresentados irão ajudar na definição e implementação de novas estratégias de conservação relevantes para a subsistência de uma população de urso pardo viável na Cordilheira Cantábrica.
Over the centuries, the brown bear geographical distribution in the Iberian Peninsula has been decreasing, being currently limited to the North of Spain. The Cantabrian brown bear population is one of the smallest populations in Europe as is fragmented in two subpopulations (Western and Eastern), with limited connection between them. Additionally, human persecution represents serious threats to the survival of brown bear in Cantabria. Considering the current status of the Cantabrian population, it is essential to have a clear picture of the genetic patterns of the population. We used three molecular markers (mitochondrial DNA, autossomal and sex linked microsatellites) to assess the genetic origins, structure, diversity and gene flow of the Cantabrian brown bear population. Our results suggest that the Cantabrian population is divided in two distinct matrilineal lineages and is not monophyletic relative to other European populations. This differentiation, in an east-west axis might be related with colonization events of the Cantabrian mountains prior and contemporary to the last glacial maximum. The population is structured in two subpopulations with great genetic differentiation between them. The results also show strong evidences of migration between both subpopulations. Namely, we found evidence of asymmetrical gene flow and greater migrant flow from the Eastern to the Western subpopulation. However, results also suggest greater genetic admixture in the opposite way. This study reveals the origins and provides new insights on the genetic condition and migration patterns of the brown bear population. The results here presented will help in the definition of conservation strategies relevant for the maintenance of a viable brown bear population in the Cantabrian mountains.
14
Cilingir, Fatma Gozde. « Maternal Phylogeography Of Brown Bears (ursus Arctos) And Testing The Utility Of Non-invasive Genetic Samples ». Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615071/index.pdf.
Texte intégralRésumé :
The genetic diversity and phylogeography of brown bear maternal lineages have been studied extensively over the last two decades. In this study the genetic diversity and maternal phylogeography of non-invasively sampled 35 brown bears, including 5 captive individuals were reported from Turkey. In addition to the optimization of DNA extraction from hair, faeces and old skin samples and their PCRs, Bayesian phylogenetic analyses based on a 269 bp long piece of bear mitochondrial DNA were conducted and 14 novel haplotypes belonging to three major lineages were revealed. The most widespread lineage was found to be the &ldquoEastern&rdquo
clade 3a, while geographically more restricted &ldquo
Western&rdquo
and &ldquo
Middle Eastern&rdquo
lineages were reported for the country for the first time. A specimen from the Taurus range (southern Turkey) was shown to be closely related to the presumably extinct bears in Lebanon. Moreover, a unique novel lineage that appears to have split early within the Middle Eastern clade was defined. Despite limited sampling, this study demonstrates a high level of mitochondrial diversity in Turkish brown bears, extends the ranges of both European and Middle Eastern clades into Turkey, and identifies a new divergent lineage of possibly wider historical occurrence while demonstrating the significance of non-invasive genetic sampling for such analysis.
15
Ambarli, Huseyin. « Spatio-temporal Ecology, Habitat Use And Population Size Of Brown Bears (ursus Arctos) In Yusufeli, Turkey ». Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615103/index.pdf.
Texte intégralRésumé :
Brown bear is the largest mammal in Turkey and its main distribution lies in the Black Sea and Eastern Anatolia Regions. Its basic ecology is almost unknown in Turkey, except for a limited number of studies. This study aims to determine the spatio-temporal ecology and habitat use of brown bears in the Kaçkar Mountains, and to estimate their population size in the Ö
zgü
ven Valley and Yusufeli, both firsts for Turkey. The study area is primarily covered with conifer and oak stands, but sparse mixed shrubland occurs in the Mediterranean climate influenced lower parts. GPS-GSM telemetry on seven captured bears (5 males and 2 females) was the main field technique used in this study. Other methods include monitoring via camera trapping, visual direct observations, and counting cubs of the year. Bears were fitted with GPS-GSM collars and tracked for 3 to 603 days. Mean home range size (HRS) was calculated by 95% kernel and MCP estimators for three different samples sizes.95% MCP for all positions produced a home range size of 19.91 ±
8.89 sq. km. for females, and 130.68 ±
102.95 sq.km. for males. On average, males and females move at rates of 199 m/h and 129 m/h, respectively. Males hibernate around 140 days whereas females around 150 days and at lower elevations than males. According to camera trapping results, bears are generally active at twilight whereas activity data loggers produced disparate results for tracked bears. Resting patterns showed that bears may also rest at midnight. Estimated population density per 100 km2. is 24.50 ±
1.74 individual using the Fcub method and 23.85 ±
2.51 using the mark&ndash
resight method. Captured bears indicated nonrandom distribution on habitat use and selected productive croplands and shrublands than other types of vegetation. Brown bear HRS in the Kaç
kars is smaller than reported from most countries. The large female-male HRS difference is probably due to polygamous mating system, sexual dimorphism, hard mast availability, high population density, and female&rsquo
s habitat exclusivity as a result of high tolerance by the local people in contrast with most northern countries. Although primary productivity is used to explain high population density and small HRS in other countries, the low productivity in the study area cannot explain the observed density and HRS difference. These findings will construct a scientific basis for brown bear management and conservation in Turkey.
16
Mace, Richard D. « Human impacts on grizzly bear Ursus arctos horribilis habitat, demography, and trend at variable landscape scales / ». Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5635-5.pdf.
Texte intégral
17
Clapham, Melanie. « Chemical signalling in brown bears ,ursus arctos : an assessment of scent marking strategies and social function ». Thesis, Lancaster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.660117.
Texte intégralRésumé :
For many species, chemical signalling is used to signal the competitive ability of individuals and therefore plays an important role in the breeding system. As breeding generally promotes intrasexual competition, the potential fitness costs associated with competitive behaviour may be mitigated if individuals are able to assess their own ability, and the competitive ability of others, prior to agonistic encounters. Due to their hierarchical social structure and large home-range size, bears (Ursidae) are thought to rely highly on olfactory methods of communication. It is well known that bears rub parts of their body against trees. Selectivity in the trees used and seasonal variation of rubbing behaviour suggest it is a form of scent marking. However, methods of scent deposition and the function of tree marking have received little attention. This study documents tree marking behaviour in brown bears Ursus m'etos to investigate its role as a method of chemical signalling. Using observational research methods, the location of marking trees, frequency of scent marking, time invested in scent marking and receiving scents, and motor patterns exhibited at marking trees, were all investigated for each age sex class in both the breeding and non-breeding season. The observed behaviours were evaluated in terms of their potential fitness benefits to the individuals concerned. Ecological analyses indicated that bears are highly selective in the species, size and location of trees used for marking. Behavioural analyses identified seasonal and inter- sexual variation in tree marking behaviour, as well as a stereotyped pattern of marking. Analysing the time and energy brown bears invest in receiving marks and scent marking indicated variation between age sex classes. Overall, adult males appeared to invest the most time and energy in tree marking, which could indicate that they . gain a net fitness benefit from chemical signalling. The behaviour of other age sex classes at marking trees, particularly subadults and females with young, appears to be dictated by the behaviour of adult males in the area at that time, which causes seasonal variation. Brown bears appear to be highly selective in where they place scent marks, how often they engage in marking behaviour, and how much time and energy they invest in scent marking and investigating scent. It is hypothesised that the function of tree marking is to communicate competitive ability between individuals, with dominant individuals signalling their high competitive ability and receivers detecting theses cues and modifying their behaviour accordingly. Marking trees may also function in individual recognition of conspecifics, and could facilitate scent matching. This study suggests that scent marking plays an important role in the social behaviour of brown bears.
18
Montaudouin, Séverine. « Signification des activités des Ours bruns (Ursus arctos) en captivité : perspectives d'amélioration de leur bien-être ». Paris, Muséum national d'histoire naturelle, 2005. http://www.theses.fr/2005MNHN0002.
Texte intégralRésumé :
Des ours bruns captifs (n= 66) ont été observés dans 28 parcs afin d'évaluer l'importance des stéréotypies (st. ) et la qualité des interactions. Les modalités d'élévage et d'environnement ont été comparées. 78% des ours adultes présentaient des st. Surtout ceux enfermés pendant la nuit, les st. étaient alors plus fréquentes l'après-midi. Les mouvements de tête étaient surtout présents chez les jeunes. Aucune association n'a été trouvée entre les st. Et les caractéristiques des enclos mis à part le lien entre un grand bassin et une moins grande fréquence de st. Enfin, garder plus de deux ours ensemble est source de conflits, il est préférable qu'ils soient en couple ou seuls. Les activités ont été étudiées de manière approfondie chez 16 de ces sujets. L'occupation de l'espace, l'impact des visiteurs et des soigneurs, ont également été étudiés. Les animaux présentés dans l'enclos le plus grand ont été caractérisés par beaucoup de jeux et autres interactions, d'alimentation et d'attention ; ils étaient aussi parmi les plus jeunes. Les animaux d'âge moyen, dans de petits enclos, présentaient beaucoup de st. Ces dernières peuvent s'intensifier lors de l'attente des repas, d'autant plus si les animaux sont nourris le soir. Le repos et les st. Sont particulièrement localisées, les st. Sont souvent accompagnés d'une attention aux visiteurs. Enfin, une réduction progressive de la fréquence des st. A pu être observée chez deux femelles en l'absence de leur congènère mâle. Des améliorations de tous les jours peuvent être apportées en vue de favoriser le jeu, permettre le repos et réduire la fréquence des stCaptive brown bears (n=66) kept in 28 different parks were observed in order to assess the level of stereotypies (st. ) and interactions. Husbandry methods and design were compared. 78% of adult bears exhibited st. Especially if they were locked inside by night. In that case, st. Were more numerous during afternoon. Head turns were especially exhibited by young animals. No connection between st. And environmental factors was found, except that larger pool was significantly linked with lower levels of st. Finally, keeping more than two bears together was a potential source of social conflict, they should be kept in couple or lonely. More detailed observations were collected on the behaviour of 16 of them. The way in which the subjects used areas was also studied, with regard to effect of visitors and keepers. The largest enclosures, exhibiting young animals, were characterised by high scores of play, interactions, eating, and attention behaviours. Medium age animals in small enclosures exhibited high rates of st. Anticipation of feeding time can result in high levels of st. , especially when feeding occured late in the day. Some areas were used more frequently, rest and st. Were the most located behaviours. St. Were often linked with the amount of attention that bears paid to visitors. Lastly, a gradual reduction in frequency in st. In two females was observed after the death of their male cage mate. Changes can be suggested to the day to day husbandry to stimulate play, allow resting and reduce st
19
Giangregorio, Patrizia <1986>. « Challenging the loss of genetic variability in Italian brown bears (Ursus arctos) - A genome-wide approach ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8692/1/PhD_Thesis_Giangregorio.pdf.
Texte intégralRésumé :
The first part of this PhD thesis is devoted to the application of molecular genetics to describe demographic trends, geographic distribution patterns and genetic status of the Alpine population 15 years after the reintroduction program. In order to achieve the first objective we a) increased the number of STR markers (from 10 to 15 loci) in the Alpine population to raise the informativity content for population genetics studies, and possibly resolve uncertain parentage assignments; b) presented an annual overview of the demographic status of the Alpine population for a long-term monitoring program; c) measured the genetic diversity over generations, highlighting possible trends d) identified parentage relationships and provided a pedigree reconstruction, showing if there is an increase of inbreeding events over generations; e) estimated the effective population size; f) verified whether or not a connection between the reintroduced population in the central Alps and the Dinaric population was established. We furthermore provided considerations for conservation and management of this species in the Alps, taking into account the emerged demographic, spatial and genetic aspects.
The second part is methodological and is about developing a new set of SNP markers to enhance the resolution power
for population genetics analysis of the Alpine and Apennine populations. In order to identify reliable and informative SNPs we a) tested the effectiveness of an existing SNP panel, developed for the Scandinavian brown bear populations, on the two Italian brown bear subspecies, identifying a set of SNPs that has potential for a SNP-based individual and sex identification system. I took into consideration the ascertainment bias that arises when transferring SNP markers across populations; and b) tested the selected subset of SNPs for parentage assignments in the Alpine population, comparing its resolution power with that derived from STRs.
20
Granström, Sundgren Johanna. « Att arbeta där brunbjörnen lever : Påverkan vid ensamarbete i skogen ». Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-105142.
Texte intégralRésumé :
De som arbetar där brunbjörnen (Ursus arctos L.) lever riskerar att påverkas genom olycksfall och ohälsa, vilket kan leda till ett arbetsmiljöproblem. Björnpopulationen har efter upp- och nedgångar ökat senaste årtiondena vilket har ökat incidenterna. Syftet med studien var att kartlägga hur anställda som arbetar ensam till fots i fält inom skogsnäringen påverkas av björnens närvaro i skogen och att utreda vad som skulle kunna göra skogen till en säkrare arbetsplats genom att motverka ohälsa och olycksfall kopplat till björnens närvaro. En litteraturstudie och en enkätstudie gjordes för att uppfylla syftet. Resultatet av enkätstudien blev tvetydigt eftersom respondenterna var positivt inställda till björn trots att majoriteten kände sig illa till mods på grund av den. En kollega ansågs vara en trygghet trots att väldigt få var emot ensamarbete. Av respondenterna hade majoriteten varit med om minst ett björnmöte. Som slutsats; utbilda, förekom och försvara.
21
Gustafsson, Jonas. « Effektivisering av urvalsprocesser vid analysering av björnspillning : Ett förslag till den svenska förvaltningen av brunbjörn Ursus arctos ». Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-103582.
Texte intégralRésumé :
The aim with this report is to formulate a strategic method to optimize selection processes of DNA-samples from a faeces inventory to identify as many individuals in as few analyzes as possible, and by that keep down the costs of brown bear management. Brown bear management in Sweden founds today on results from faeces inventory and is substantially led by the county administration boards. Data from the years of 2004 and 2009´s inventories in Västerbotten was used to test and evaluate different methods in selection processes of which faeces that should be sampled. Comparison were made between making selection by chance, by spatial distribution and by calculating variations in logistic regressions coefficient b, in other words bear density and probability in finding same individual in several faeces. We can show making selection by chance is the most uncertain method. Making selection by spatial distribution, without take in account variations in b, provides the highest number of identified individuals at a low labour and thus a low cost. Therefor we strongly recommend future brown bear management to, if not possible to sample all faces in a dataset, make selection by spatial distribution to minimize the risk of sampling the same bear several times.
22
Cabral, Pedro Miguel Matos. « Brown bear behaviour in human-modified landscapes : the case of the endangered Cantabrian population, NW Spain ». Master's thesis, Universidade de Évora, 2019. http://hdl.handle.net/10174/26700.
Texte intégralRésumé :
Large carnivore populations are recovering in Europe after centuries of population decline. The Cantabrian brown bear Ursus arctos population is endangered, and it is a good example of a large carnivore inhabiting a human-modified landscape. In order to study the impact of human landscape elements on bear behaviour we analysed 10 years of Cantabrian brown bear records. Human activity and structures do not appear to have an impact on the duration or appearance of vigilance behaviour. While bears avoid direct contact with humans, the mere presence of human infrastructure and activities don't not appear to impact its vigilance behaviours. The brown bear seems to be adapted to human coexistence and this should give a different perspective in future conservation efforts; Comportamento do Urso-Pardo em paisagens modificadas pelo Homem: o caso da população Cantábrica em perigo, NO Espanha
Resumo:
As populações de grandes carnívoros estão a recuperar por toda a Europa após séculos de declínio populacional. A população Cantábrica de urso pardo Ursus arctos encontra-se em perigo e é um bom exemplo de um grande carnívoro que habita uma paisagem modificada pelo Homem. A fim de estudar o impacto dos elementos da paisagem humanizada no comportamento do urso pardo, analisamos 10 anos de registos de comportamento de urso pardo Cantábrico. A atividade e estruturas humanas não parecem ter impacto na duração ou no aparecimento do comportamento de vigilância. O urso-pardo evita o contato direto com os seres humanos, no entanto a mera presença de infraestruturas e atividades humanas não parece ter impacto no comportamento de vigilância. O urso-pardo parece estar adaptado à coexistência humana e isso deverá dar uma perspetiva diferente a futuros esforços de conservação.
23
Piédallu, Blaise. « Approche intégrative de la gestion des conflits homme-nature : le cas de l'ours brun en France ». Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT164/document.
Texte intégralRésumé :
La conservation des populations animales autour desquelles existe une controverse passe entre autres par une compréhension de l’écologie de l’espèce, mais également par une analyse des attitudes humaines vis-à-vis de sa présence. Cependant, ces deux aspects sont rarement mobilisés ensemble au sein de travaux combinant sciences de l’environnement et sociologie. Nous proposons ici une étude portant sur la population d’ours brun (Ursus arctos) résidant dans les Pyrénées, intégrant à la fois dynamique de la population et de sa distribution, et une analyse de l’attitude des Pyrénéens vis-à-vis des plantigrades. Nous conduisons également une réflexion sur les méthodes à employer afin d’intégrer ces résultats au sein d’une approche socio-écologique. Nos modèles écologiques, qui utilisent des données de suivi obtenues dans le cadre d’un partenariat transfrontalier entre France, Andorre et Espagne, mettent en évidence une augmentation des effectifs et une réduction de la distribution de la population entre 2008 et 2014. Si ces conclusions ne semblent pas aller dans le sens d’une dégradation rapide de leur état de conservation, les ours pyrénéens restent menacés du fait de leurs faibles effectifs et du fort taux de consanguinité au sein de la population. Notre enquête sociologique, réalisée dans les communes sur lesquelles l’ours est ou a été présent entre 2008 et 2013, a mis en évidence une hétérogénéité spatiale dans l’attitude des habitants des Pyrénées sur la question de l’ours, avec notamment des variations significatives en fonction de leurs lieux de naissance et de résidence. Nous discutons ensuite d’une approche intégrant résultats de sociologie et d’écologie avec le but de créer un modèle pouvant servir d’outil à un responsable chargé de la gestion ou de la résolution du conflit, en analysant les méthodes à notre disposition, leurs avantages et leurs limites. Nous concluons sur l’intérêt des approches pluridisciplinaire dans la gestion des controverses autour de la conservation de populations animalesThe conservation of controversial animal populations requires an understanding of the species’ ecology, but also an analysis of the human attitudes towards its presence. However, those two aspects are rarely studied together through a combination of environmental sciences and sociology. Here we study the brown bear (Ursus arctos) population residing in the Pyrenees mountains, analyzing both population dynamics and distribution, and the attitudes of Pyrenean people towards the species. We also ponder on the methods to use to combine these results in a socio-ecological approach. Our ecological models, which use monitoring data obtained through a crossborder partnership between France, Andorra and Spain, highlight an increase of population size and a reduction of its distribution between 2008 and 2014. If those conclusions do not seem to indicate a quick degradation of their conservation status, Pyrenean brown bears remain threatened by low numbers and high inbreeding in the population. A sociological study was performed in the municipalities where bear was or had been present between 2008 and 2013. We found spatial heterogeneity in the attitudes of Pyrenean people regarding bears, with significant variations depending on where they were born and where they currently live. We follow by discussing an approach that combines sociological and ecological results, with the goal of building a model that can be used as a tool for someone responsible for managing or solving the conflict; to do this, we analyze the methods available, their strengths and limits. We conclude on the importance of interdisciplinary approaches when managing controversies over wildlife conservation
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Narita, Ryo. « A study on food habits of Japanese ursid species Ursus arctos and U. thibetanus using stable isotope methods ». Kyoto University, 2007. http://hdl.handle.net/2433/136531.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第13112号
農博第1617号
新制||農||941(附属図書館)
学位論文||H19||N4238(農学部図書室)
UT51-2007-H385
京都大学大学院農学研究科森林科学専攻
(主査)教授 井鷺 裕司, 教授 武田 博清, 助教授 岡田 直紀
学位規則第4条第1項該当
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Simeoni, Nicola <1991>. « “L’orso bruno (Ursus arctos) nelle Alpi Centrali : indagine sulle dinamiche di dispersione femminile a 14 anni dai rilasci" ». Master's Degree Thesis, Università Ca' Foscari Venezia, 2017. http://hdl.handle.net/10579/11658.
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Gosselin, Jacinthe. « Influence de la chasse et de l'infanticide sur la dynamique de la population de l'ours brun scandinave (Ursus arctos) ». Mémoire, Université de Sherbrooke, 2014. http://hdl.handle.net/11143/5382.
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Le maintien des populations de grands carnivores est un élément clé dans le maintien des écosystèmes. L'étude de la dynamique des populations permet de comprendre et d'anticiper les fluctuations en taille de population et est donc un outil essentiel dans la gestion et la conservation des espèces. En Suède, la population d'ours bruns (Ursus arctos) a connu une forte croissance depuis le début du 20e siècle. Conséquemment, les quotas de chasse ont augmenté de façon fulgurante depuis le début des années 2000. Or, les effets de la chasse sur la dynamique de la population restent encore méconnus et donc, les conséquences de cette augmentation sur le taux de croissance de la population sont inconnues. La chasse devrait avoir des impacts particulièrement importants dans cette population, puisque plusieurs études suggèrent qu'une augmentation de la chasse mènerait non seulement à une augmentation de la mortalité des classes d'âge exploitées, mais aussi à une augmentation de la mortalité des oursons à travers une augmentation de l'infanticide sexuellement sélectionné (où les mâles tuent les jeunes qui ne sont pas les leurs pendant la saison de reproduction pour augmenter leurs opportunités de reproduction).
Mon projet avait donc pour but de quantifier les effets directs ainsi que l'effet potentiellement indirect de la chasse à travers l'infanticide sexuellement sélectionné sur la dynamique de la population d'ours brun en Suède. Les objectifs spécifiques de mon projet étaient de : i) quantifier comment les taux démographiques et le taux de croissance de la population varient sous faible et forte pression de chasse; et de ii) déterminer l'importance des différents taux démographiques, dont la survie des oursons, sur le taux de croissance de la population.
Pour ce faire, j’ai collaboré au suivi individuel à long terme d’ours bruns dans le centre-sud de la Suède effectué par le Scandinavian Brown Bear Research Project. À l'aide de ces données, j'ai construit des modèles matriciels de la population qui permettent de calculer son taux de croissance ainsi que l'importance relative des différents taux démographiques pour la croissance de la population. J'ai élaboré un modèle pour l'ensemble de ma période d'étude (1990-2011) ainsi que des modèles distincts pour deux périodes qui diffèrent par la pression de chasse : de 1990 à 2005 avec une pression de chasse relativement faible, et de 2006 à 2011 avec une forte pression de chasse.
J'ai trouvé que la grande majorité des taux démographiques étaient plus faibles sous une forte pression de chasse : ceci se reflétait par un taux de croissance asymptotique légèrement en deçà de 1, indiquant ainsi un déclin de la population. La survie des oursons était plus faible sous forte pression de chasse, probablement en raison d'une augmentation de l'infanticide sexuellement sélectionné. D'ailleurs, la survie des oursons avait une influence relativement forte sur le taux de croissance de la population. Finalement, j'ai aussi pu quantifier l'impact de l'infanticide sexuellement sélectionné sur le taux de croissance de la population. J'ai trouvé que le comportement était très important, puisque s’il n'y avait pas d'infanticide sexuellement sélectionné dans la population, celle-ci aurait été en croissance même sous forte pression de chasse. Ainsi, mon projet de recherche a mis en évidence l'importance du comportement individuel et des effets indirects de la chasse pour la dynamique d'une population sauvage. Les effets indirects de l'exploitation sont bien souvent méconnus et doivent être étudiés davantage afin que nous comprenions l'impact réel sur les populations exploitées.
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Valentini, Alice. « Etude non-invasive du régime alimentaire basé sur le DNA barcoding : l’ours brun himalayen (Ursus arctos isabellinus) comme cas d’étude ». Université Joseph Fourier (Grenoble), 2008. http://www.theses.fr/2008GRE10030.
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L'étude des réseaux trophiques et leur dynamique sont fondamentales pour comprendre comment les habitudes alimentaires des différentes espèces peuvent influencer la communauté. En outre, l'étude de l'écologie alimentaire devient cruciale lorsqu'il s'agit des espèces en voie de disparition, une connitissance précise de leur alimentation doit être acquise lors de la conception des stratégies de conservation. Un large éventail de méthodes a été 1 proposé pour l'analyse du régime aiimentaire, y compris les plus simples, comme l'observation visuelle du comportement d'alimentation, et les plus complexes, comme la spectrométrie dans le proche infrarouge et les méthodes basées sur l'ADN, comme le DNA barcoding. Dans cette étude, nous proposons l'intron tmL (UAA) en tant que marqueur pour le DNA barcoding des plantes. Le pouvoir et les limites de ce système ont été évalués, ainsi que la possibilité d'identification des espèces avec de l'ADN fortement dégradé. Ce système a été couplé avec la technique du pyroséquençage pour l'étude du régime alimentaire des herbivores. Nous avons démontré l'efficacité de cette nouvelle approche par l'analyse de l'alimentation de différentes espèces herbivores. Notre approche a été ensuite associée à l'identification individuelle et le sexe en utilisant le polymorphisme de microsatellites dans l'ours brun himalayen (Ursus arctos isabellinus). Nous avons examiné cette population au moyen de l'analyse d'ADN des fèces et de données de terrain. La différenciation sexuelle et individuelle du régime alimentaire, ainsi que ses variations temporelles et géographiques ont été évaluéesThe study of food webs and their dynamics is fundamental to understand how the feeding habits of the different species can affect the community, th us improving our understanding of the functioning of the ecosystem as a whole. Furtherrnore, the study offeeding ecology becomes crucial when it concerns endangered species since a precise knowledge of their diet is to be gathered when designing reliable conservation strategies. A wide range of methodologies have been proposed for diet analysis, including simple ones, as visual observation of foraging behavior, and more complex on es such as Near Infrared Reflectance Spectroscopy and DNA based methods, such as DNA barcoding ln this study we propose the tmL (UAA) intron as marker for plant DNA barcoding. The power and the limitations ofthis system were evaluated as weil as the possibility of species identification with highly degraded DNA. This system has been coupled with massively parallel pyrosequencing technique for diet analysis of herbivores We demonstrate the efficiency of this new approach by analyzing the diet of various herbivorous species. Furtherrnore, our approach was coupled with individual and sex identification using microsatellites polymorphism in the Himalayan brown bear (Ursus arctos isabellinus). We examined this population using a combination of fecal DNA analysis and field data with the aim to study individual and sexual differentiation in the diet, and also temporal and geographical variations
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Kantelis, Theron Michael. « Black Bears (Ursus americanus) versus Brown Bears (U. arctos) : Combining Morphometrics and Niche Modeling to Differentiate Species and Predict Distributions Through Time ». Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etd/3262.
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Late Pleistocene American black bears (Ursus americanus) often overlap in size with Pleistocene brown bears (U. arctos), occasionally making them difficult to diagnose. Large U. americanus have previously been distinguished from U. arctos by the length of the upper second molar (M2). However, the teeth of fossil U. americanus sometimes overlap size with U. arctos. As such, there is need for a more accurate tool to distinguish the two species. Here, 2D geometric morphometrics is applied to the occlusal surface of the M2 to further assess the utility of this tooth for distinguishing U. americanus and U. arctos specimens. When combined with an Ecological Niche Model of U. americanus and U. arctos in North America from the Last Glacial Maximum, this morphometric technique can be applied to key regions. A case of two Pleistocene specimens previously identified as U. arctos from eastern North America exemplifies the utility of this combination.
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Bogner, Emily. « Differentiating Black Bears (Ursus americanus) and Brown Bears (U. arctos) using Linear Tooth Measurements and Identification of Ursids from Oregon Caves National Monument ». Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etd/3572.
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North American black bears and brown bears can be difficult to distinguish in the fossil record due to similar dental and skeletal morphologies. Challenges identifying ursid material from Oregon Caves National Monument (ORCA) called for an accurate tool to distinguish the species. This study utilized a large database of lower tooth lengths and ratios in an attempt to differentiate black and brown bears in North America. Further, this project examined how these linear measurements differ geographically. Analysis of variance (ANOVA) found significant differences between black and brown bears from across North America for every variable studied. Stepwise discriminant analyses (DA) found lengths separated species better than ratios. When sexes were analyzed, ANOVA only found significant differences for lengths while DA found lengths and ratios could not accurately distinguish between sexes. Fossil specimens from North America, including ORCA specimens, demonstrated the utility of this study, supporting several identifications and questioning others.
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Crupi, Anthony P. « Foraging Behavior and Habitat Use Patterns of Brown Bears (Ursus arctos) in Relation to Human Activity and Salmon Abundance on a Coastal Alaskan Salmon Stream ». DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/4777.
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Over the past decade, demand for recreation has increased as part of Alaska's doubling growth in tourism. Along the Chilkoot River, near Haines, fishing and bear viewing have become increasingly popular. I investigated the ecological and behavioral interactions there between two brown bears, salmon, and humans between 2000 and 2002. My objectives were to: (1) determine if specific human activities differentially influenced bear activity and foraging behavior, (2) identify temporal and spatial habitat use patterns, (3) evaluate brown bear response to natural and human disturbances and quantify related flight distances, (4) investigate changes in bear foraging behaviors in response to prey abundance and human activity to find if bears selectively forage to maximize energy intake, and (5) assess the role of individual tolerance for human proximity in relation to specific foraging behaviors.
Evidence clearly indicated that temporal and spatial brown bear activity patterns were influenced by human activity. Bears were most active and spent the longest periods of time fishing when the numbers of anglers and vehicles were below threshold levels. Adult female bears disproportionately preferred (73%) non-roaded riparian habitat, while subadults were less selective. I classified over 1000 disturbance responses and found human activity accounted for 46% of bear departures with a mean flight response distance of 97 meters. When humans were either absent or at distances greater than or equal to 100 meters from bear activity, bears captured fish at higher rates, captured 2.65 times as many fish, and caught greater proportions of live fish (71%). The greatest predictors of capture rate were the time of day when bears fished, the proximity of human activity, and the individual's tolerance level. Bear tolerance for human proximity helped explain variation in capture rates, foraging bout lengths, and total salmon captured. This suggests nutritional rewards for bears adapting to human disturbance.
These analyses depict clear relationships with simple interpretation of the dynamic relationships between people, bears, and their environment. With improved understanding of the Chilkoot River's natural resources, managers can work to reduce bear-human conflicts and plan for continued growth in tourism and recreation.
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Wenker, Christian J. Wenker Christian J. « Dentale Affektionen beim europäischen Braunbären (Ursus arctos SSP.) im Zoo unter besonderer Berücksichtigung der Bären im Berner Bärengraben = Dental affections of the European brown bear (Ursus actos SSP.) in a zoological garden with special consideration of the bears in the Berneses Bear Pit / ». [S.l.] : [s.n.], 1997. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Mertzanis, Georges. « "Aspects biogéographiques et écologiques des populations helléniques d'ours brun (Ursus arctos L. ) : cas d'une sous-population du Pinde : application à la conservation de l'espèce et de son habitat" ». Montpellier 2, 1992. http://www.theses.fr/1992MON20049.
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Une retrospective paleozoogeographique de certains representants de la famille des ursides retrace les conditions de leur mise en place et de leur evolution en europe et dans la peninsule balkanique. Apres un inventaire du statut de l'espece en europe, on etudie l'evolution de sa repartition en grece. Certains parametres de la dynamique des populations, en liaison avec la mortalite anthropique, montrent des tendances regressives au niveau des effectifs. L'etude du regime alimentaire confirme la nature opportuniste des habitudes trophiques. L'etude des rythmes d'activite annuelle est basee sur la methode indirecte de releves d'indices et corroboree par des enquetes sur le terrain. Pour l'etude des modalites d'utilisation de l'habitat, nous avons tenu compte du relief et des communautes vegetales. L'interface ours-homme revele certaines incompatibilites au niveau du maintien des effectifs et de la structure de l'habitat
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Skuban, Michaela [Verfasser], et Matthias [Akademischer Betreuer] Starck. « Bears among people : human influence on diet, daybed selection, habitat selection, and road crossing behaviour of the brown bear (Ursus arctos) in central Slovakia / Michaela Skuban ; Betreuer : Matthias Starck ». München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2018. http://d-nb.info/1185393870/34.
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Kinka, Daniel. « Evaluating the Effectiveness of Livestock Guardian Dogs : Loss-Prevention, Behavior, Space-Use, and Human Dimensions ». DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7611.
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Livestock guardian dogs – or “LGDs” – are commonly used by domestic sheep ranchers and reduce the need for killing wild carnivores to protect livestock. LGDs are mostly used in the United States to reduce the number of livestock killed by coyotes, but whether they can prevent killing by larger carnivores like wolves and grizzly bears is unclear. It is important to identify which behavioral traits and LGD breeds work best for guarding livestock so that ranchers can protect their stock and environmentalists can enjoy a greater number of wild animals on the landscape. This study investigated the effectiveness of different LGD breeds in the Western U.S. to help determine how best to use LGDs. I investigated (1) which LGD breed works best for each predator, (2) if LGD breeds behave differently, (3) how carnivores respond when LGDs and sheep move through their home ranges, and (4) whether having good LGDs makes ranchers more accepting of predators. I compared common U.S. breeds of LGD with three exotic breeds used primarily in other countries with wolves and grizzly bears. From 2013 – 2016 data was collected on sheep that were killed and what killed them, how different LGD breeds behaved, what carnivore species were present near sheep grazing with LGDs, and ranchers’ attitudes towards LGDs and large carnivores throughout Idaho, Montana, Oregon, Washington, and Wyoming. Results of the study show that all three of the exotic breeds of LGD are better at protecting sheep from certain predators than LGD breeds commonly used in the U.S. There are also some breed differences in LGD behavior that may help ranchers make better decisions about which LGD breed is best for them. Sheep grazing with LGDs seemed to drive-off wolves, but they also attracted smaller carnivores. Also, ranchers’ attitudes about LGDs are generally very positive, but they don’t affect attitudes about wolves and grizzly bears. Below, I discuss these and other findings in terms of both ecology and wildlife management.
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Agzitemiz, Mehmet Melih. « Study Of Effects Of Selective Hunting On A Bear Population Through Pva Simulation ». Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610026/index.pdf.
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Management of big wildlife such as bears can be a difficult task, especially in the face of human-wildlife conflict and demands of the hunting industry. The Brown Bear (Ursus arctos) population at Yusufeli County (Artvin, northeastern Turkey) has recently been the focus of scientific, social and economic concerns. This study population of c. 140 individuals occurs within 800 km2 of forested and alpine land. Legal hunting of male bears was allowed in 2007 after an interval of four years. This study aims to find out through a population viability analysis the level and frequency of trophy hunting this population can tolerate for the next 50 years. A matrix model with six age-classes for each sex was constructed using observed and literature-based parameter values. RAMAS Metapop was used to simulate four different scenarios where numbers of hunted bears and hunting frequency changes.
The model was highly sensitive to maximum growth rate and adult survival. Interval extinction probabilities for the next 50 years ranged between 0% and 26% depending on the scenario. Viable scenarios (with an extinction probability <0.05) were only possible with either no trophy hunting or hunting of 4 subadult/adult males and 1 adult female every other year. Legal and illegal hunting jointly impact the bear population in a strong way, and when they occur simultaneously every year, they lead to extinction in the long run. Avoidance of illegal killing and a close supervision of trophy hunting are crucial in the management of this bear population.
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GUIDARELLI, Giulia. « Geometric morphometrics and conservation of wide ranging mammals. Identifying Management Units and Evolutionary Significant Units in the brown bear Ursus arctos and in three Mediterranean Dolphins (Stenella coeruleoalba, Delphinus delphis, Tursiops truncatus) ». Doctoral thesis, Università degli studi del Molise, 2017. http://hdl.handle.net/11695/79683.
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Lo studio della morfologia ha sempre avuto un ruolo fondamentale in molti ambiti delle scienze naturali, come nella tassonomia e nello studio della variabilità geografica.
La morfometria geometrica permette di indagare la variazione di taglia e forma attraverso efficaci mezzi grafici e statistici, contribuendo all’identificazione e all’interpretazione di pattern di variabilità fenotipica sia a livello microevolutivo che macroevolutivo.
In questo progetto di ricerca ho applicato le tecniche della morfometria geometrica bidimensionale per studiare la morfologia della mandibola in mammiferi ad ampia distribuzione di particolare interesse conservazionistico: tre delfini Stenella coeruleoalba (Meyen, 1833), Delphinus delphis Linnaeus, 1758, Tursiops truncatus (Montagu, 1821) e l’orso bruno Ursus arctos Linnaeus, 1758. Il principale scopo è quello di verificare se lo studio della morfologia mandibolare sia efficace nel riconoscere le unità tassonomiche e nell’identificarne le componenti adattative e filogenetiche, sia a livello intraspecifico sia interspecifico.
Nei primi due articoli della tesi, ho analizzato la variabilità interspecifica in tre specie di delfini provenienti dal Mare Mediterraneo e dall’oceano Atlantico. La mandibola dei delfini è suddivisa dal punto di vista morfologico in due moduli corrispondenti al ramo e al corpo, che potrebbero riflettere a loro volta una separazione sul piano funzionale corrispondente alle aree adibite all’udito e all’alimentazione. Il foramen mandibolare ha inoltre permesso di distinguere chiaramente le tre specie, essendo l’unico carattere diagnostico per il riconoscimento interspecifico. Le popolazioni Atlantiche si discriminano da quelle Mediterranee e i pattern di variazione fenotipica attraverso il gradiente geografico sono diversi nel tursiope rispetto alle altre due specie.
Nel terzo articolo ho preso in considerazione la componente filogenetica della mandibola degli odontoceti, ricostruendone la forma ancestrale al fine di analizzare la sua evoluzione attraverso il clade, testando al contempo se la variazione morfologica sia stata soggetta a pressioni selettive. La forma della mandibola si è evoluta sotto l’azione di pressioni selettive e un segnale filogenetico significativo è stato individuato nella forma ma non nella taglia. La ricostruzione della forma ancestrale è relazionabile a una dieta generalista che si è evoluta nel tempo verso diete più specializzate.
L’ultimo capitolo riguarda la famiglia Ursidae e, in particolare, la variabilità morfologica dell’orso bruno, e ha l’obiettivo di identificare l’influenza della tassonomia, del clima e della taglia sulla variabilità della forma mandibolare. La mandibola, nelle sue componenti di forma e taglia, è in grado di distinguere le specie con un’elevata percentuale di accuratezza. Inoltre, le due sottospecie Ursus arctos isabellinus e Ursus arctos marsicanus sono risultate essere chiaramente discriminate rispetto alle altre popolazioni di orso bruno, probabilmente come risultato di un lungo processo di isolamento.
La mandibola, nonostante la sua semplicità strutturale, è risultata essere una componente cranica estremamente informativa e ha confermato la sua efficacia nel mettere in luce le relazioni evolutive di un clade, nell’identificare tratti anatomici diagnostici utili nelle indagini tassonomiche, così come nel contribuire al riconoscimento di popolazioni distinte che potrebbero necessitare di specifiche strategie di conservazione, come nel caso dell’orso bruno marsicano o delle popolazioni di delfini mediterranei.
La presente ricerca non si sarebbe potuta realizzare senza il sostegno dei seguenti fondi: SYNTHESYS project della Comunità Europea, College Italia, Erasmus Placement projects e senza il supporto dell’Università degli Studi del Molise che ha permesso la visita alle collezioni di storia naturale nei musei di Stoccolma, Copenhagen, Edimburgo, Liverpool e New York.The study of morphology has always had a fundamental role in several fields of natural sciences, like taxonomy and geographic variation. During the 20th century, morphological studies have developed towards more rigorous traditional morphometric analyses and even further, to the last advances of geometric morphometrics. These new techniques allow scientists to test biological hypotheses on shape and size variation through a set of powerful statistical and graphic tools. Morphometrics still plays a relevant role in depicting adaptive and functional interpretations of geographic variation and macro- and micro-evolutionary pathways, thus offering a fruitful contribution in the identification of Management Units for Conservation plans. I applied two-dimensional geometric morphometrics to study the mandibular form of wide-ranging mammals of conservation concern: the closely related dolphins Stenella coeruleoalba (Meyen, 1833), Delphinus delphis Linnaeus, 1758, Tursiops truncatus (Montagu, 1821) and the brown bear Ursus arctos Linnaeus, 1758. Main aim was to evaluate the mandibular form’s effectiveness in recognizing taxonomic units and identifying its adaptive and phylogenetic constraints at the inter and intraspecific scale. In the first two articles, I analysed interspecific mandibular variation and modularity in the three dolphin species, first within the Mediterranean Sea and then extending the sampling to the Atlantic waters. The odontocete lower jaw is divided into two distinct modules: the ramus and the corpus which likely reflect a functional separation corresponding to the hearing and the feeding functions. In the Mediterranean Sea, the species were clearly differentiated in the mandibular foramen, the only diagnostic taxonomic character. The Mediterranean subpopulations discriminated from the Atlantic ones, and different patterns of phenotypic change were observed across the geographic gradient in T. truncatus with respect to the other two species. In the third article, I evaluated the phylogenetic component of odontocete mandibular form and reconstructed its ancestral shape and size to analyse trait evolution across the clade. The mandibular shape evolved under the action of selective pressures and a significant phylogenetic signal in the family Delphinidae was detected in shape but not in size. Ancestral mandibular reconstruction corresponded to that of a generalist feeder and evolved across the clade toward more specialized suction and raptorial feeder’s traits. In the last chapter, I concentrated on the family Ursidae and on the geographic variability of the brown bear to identify the impact of taxonomy, climate and size on mandibular shape variation. Both size and shape data were useful characters to discriminate extant bears species with very high percentage of accuracy. The subspecies U. a. isabellinus and U. a. marsicanus have distinct morphologies from all other brown bear populations. These taxa exhibit a high degree of morphological differentiation possibly because of a long process of isolation. The mandible proved to be an informative skull element and confirmed its effectiveness in sorting out evolutionary relationships within a clade, finding diagnostic traits for taxonomic investigations as well as contributing to the identification of distinct populations that could deserve specific resources in terms of conservation effort, as in the case of the brown bear and of the Mediterranean dolphins. This research would not have been possible without the EC-funded SYNTHESYS project, College Italia and Erasmus Placement projects and without the support of the University of Molise that allowed the visit of Natural History Museum collections of Stockholm, Copenhagen, Edinburgh, Liverpool and New York. Therefore, I would like to stress the importance of museum collections that, ever since they became established in the 19th century, still have a fundamental value in preserving specimens and guaranteeing their availability for scientific research.
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Can, Ozgun Emre. « Camera Trapping Large Mammals In Yenice Forest Habitats : A Feasibility Study For Camera Trapping Large Mammals In Yenice Forests, Turkey ». Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609974/index.pdf.
Texte intégralRésumé :
Widely applicable, quantitative field methods are needed to gather wildlife data for conservation and management initiatives in Turkey. In order to evaluate the use of camera traps in forest habitats of Turkey, we conducted a 5 phase camera trap survey by using 16 passive infrared-triggered cameras with a total sampling effort of 1200 camera trap days in Yaylacik Research Forest, a 50 km2 forest patch of Yenice Forest in Karabük during January-May 2006. The camera trap survey confirmed the presence of grey wolf (Canis lupus), brown bear (Ursus arctos), wildcat (Felis silvestris), red fox (Vulpes vulpes), badger (Meles meles), pine marten (Martes martes), roe deer (Capreolus capreolus) and wild boar (Sus scrofa) in the study area. The camera trap survey also revealed the presence of jackal (Canis aureus) and brown hare (Lepus europaeus), whose presence were not known by people living and working in the area. Contrary to the local belief, neither camera trapping survey nor ground survey confirmed the presence of lynx (Lynx lynx) in Yaylacik Research Forest. The wolf was observed to be crepuscular and the wildcat showed a diurnal activity pattern. Wildcat seemed to avoid other carnivores spatially and temporally. Simulation studies suggested that camera trap surveys should last 14 days for wolf, 13 days for wildcat, 10 days for pine marten, and 11 days for roe deer, while it is advisable to conduct longer surveys, probably 15-20 days, for wild boar, red fox and brown bears. The estimated population size for wildcat was 9 (SE=2.28227) with 95% confidence interval of 9 to 25 in the study area. A minimum of 6 brown bears were present in the study area. Our study indicated that the local knowledge about the presence of wildlife should be considered by researchers, but it cannot replace scientific surveys conducted by field biologists. This study was the first attempt to assess the presence, relative abundance, activity patterns and diversity of multiple mammal species by the use of camera trapping methodology in Turkey. The results suggest that camera trap surveys have the potential for gathering wildlife data at larger scales in Turkey, where information gap on large mammals is an obstacle for effective management and conservation of mammals.
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Taberlet, Pierre. « ADN mitochondrial et phylogéographie intraspécifique : [thèse soutenue sur un ensemble de travaux] ». Grenoble 1, 1992. http://www.theses.fr/1992GRE10017.
Texte intégralRésumé :
La mise en relation de phylogenies intraspecifiques (obtenues par l'analyse de sequences d'adn mitochondrial) avec des donnees biogeographiques permet de mieux comprendre l'histoire evolutive recente des especes animales. Les resultats obtenus concernent trois especes differentes. L'analyse des sequences de l'adn mitochondrial de la mesange bleue (parus caeruleus) dans la region grenobloise a mis en evidence deux lignees maternelles bien differenciees. Le morcellement de l'aire de repartition durant une partie du quaternaire puis le melange recent de deux populations anterieurement isolees pourrait permettre d'interpreter ce resultat. Les musaraignes du groupe sorex araneus presentent une evolution chromosomique spectaculaire. Nos resultats indiquent que l'evolution de l'adn mitochondrial et l'evolution du caryotype sont deux processus presque independants. Alors que les haplotypes mitochondriaux se trouvent tres lies a l'histoire biogeographique, les mutations chromosomiques (fusions robertsoniennes) peuvent aisement etre transmises d'une population a l'autre. L'ensemble des donnees disponibles suggerent que l'impressionnant polymorphisme chromosomique de ce groupe est un phenomene tres recent. A partir des cellules presentes a la base d'un seul poil preleve sur un ours brun des pyrenees (ursus arctos) captif, nous avons extrait l'adn total, amplifie et sequence une partie du gene du cytochrome b. La comparaison avec trois sequences homologues a permis de construire un arbre phylogenetique faisant apparaitre que l'ours brun des pyrenees se serait individualise nettement avant la divergence recente de l'ours brun d'alaska (u. Arctos) et de l'ours blanc (u. Maritimus)
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Garcia, Patrícia Matos Rodrigues. « Efeito do Enriquecimento de Ambiente no Comportamento Animal : Estudo com Ursos Pardos (Ursus arctos arctos) ». Master's thesis, 2010. http://hdl.handle.net/10348/1433.
Texte intégralRésumé :
Tese de Mestrado em Engenharia ZootécnicaCom este trabalho pretendemos avaliar o efeito do enriquecimento ambiental sobre o comportamento de ursos pardos (Ursus arctos). Para o efeito, procedemos à observação diária do comportamento de dois ursos pardos machos, antes e após o enriquecimento do seu ambiente. As observações após a introdução do ambiente enriquecido, foram realizadas em dois períodos, o período P1 e o período P2, com o objectivo de avaliar a influência das condições climatéricas no comportamento dos ursos. Os resultados obtidos sugerem que a introdução de um ambiente enriquecido no recinto dos ursos contribuiu para uma melhoria do seu comportamento, tornando-os principalmente mais activos. As diferenças comportamentais foram mais significativas no urso 2 do que no urso 1, já que, por ser bastante mais velho, o segundo animal passou a maior parte do seu tempo a descansar, embora se tenha verificado um aumento da sua actividade no período P2. A melhoria das condições climatéricas, além de aumentar a actividade de ambos os animais, desenvolveu o comportamento de nadar/mergulhar. Contrariamente ao esperado, a introdução de enriquecimento ambiental não eliminou a ocorrência de comportamentos estereotipados, apenas reduziu a sua frequência, tendo até ocorrido um aumento significativo das estereotipias no período P2 por parte do urso 2. Da análise global dos resultados resulta, finalmente, que o enriquecimento ambiental parece ser uma excelente forma de melhorar o bem-estar de ursos em cativeiro, devendo, no entanto, ser tomadas algumas precauções para evitar habituação, devendo, por isso mesmo, ser introduzido de forma gradual aos animais cativos.
To evaluate the effect of environmental enrichment on behavior of brown bears (Ursus arctos), two adult male brown bears were daily observed for two periods of time: before and after the enrichment of their environment. The second time period (after the introduction of the enriched environment) was also divided in two periods (P1 and P2), to assess the influence of weather conditions on the behavior of bears. The results show that the introduction of an enriched environment in the bears enclosure contributed to an improvement in their behavior, making them particularly more active. Behavioral differences were more significant in bear 2 than in bear 1. The fact that the bear 1 is older can probably explain why he spent most of his time resting, although there was an increase in its activity in the period P2. Improved weather conditions increased the activity of both animals, and developed the swimming/diving behavior. Against our expectations, the introduction of environmental enrichment did not eliminate the stereotypic behaviors, only reduced its frequency. There was even a significant increase of stereotypies during P2, by the bear 2. Environmental enrichment appears to be a good method to increase animal welfare. Nonetheless, care must be taken when implementing it, in order to avoid habituation and, therefore, it should be introduced gradually to animals in captivity.
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Hamilton, Jason. « Evaluation of indicators of stress in populations of polar bears (Ursus maritimus) and grizzly bears (Ursus arctos) ». Thesis, 2008. http://hdl.handle.net/10012/3488.
Texte intégralRésumé :
Grizzly and polar bears are both species at the top of the food chain in their respective ecosystems, and as such are indicative of the overall health of the ecosystem. Presently there is little data regarding the stress status of these animals. The development of reliable indicators of stress is important as both species face rapid environmental change. Polar bears from Hudson’s Bay (Ontario, Canada) and grizzly bears from Alberta, Canada, were anaesthetized and blood samples retrieved. Samples were assayed for changes in serum-based indicators of stress. Serum cortisol levels, the predominant corticosteroid in mammals and a commonly used indicator of stress, was measured to evaluate its potential as a chronic stress indicator in bears. The induction time of the cortisol response to stressor exposure is rapid and will be influenced by the stress relating to capture. Hence, serum levels of heat shock proteins (hsps), specifically the 60 (hsp60) and 70 kilodalton (hsp70) families of hsps were also measured to evaluate their reliability as a stress indicator in bears. Traditionally, heat shock proteins have been measured in tissues; however recent studies have indicated their presence in serum in response to chronic stress. In addition, the study examined the feasibility of using corticosteroid-binding globulin (CBG), a serum protein that binds cortisol, as a stress indicator in bears. CBG regulates the availability of cortisol to the tissues (only unbound cortisol elicits a response) but unlike cortisol is not rapidly regulated by acute stress. Bear CBG was isolated and a specific anti-bear CBG antibody was generated. The development of an enzyme-linked immunoadsorbant assay (ELISA) using this bear anti-CBG has the potential to be a useful tool to determine longer-term stress response in bears. Known life-history variables were correlated to the observed levels of serum indicators to elucidate which environmental factors impact bears. The length of sea ice coverage was the strongest determinant of serum cortisol and hsp70 levels in polar bears; the longer ice cover reflects more feeding time and this is reduced through climatic warming. This suggests that fasting associated metabolic changes may be impacting serum cortisol response and hsp70 levels in polar bears. For grizzly bears the proportion of protected homerange had the strongest correlation with stress indicators. This suggests that human impact on the environment, including resource extraction and landscape changes, result in altered levels of serum cortisol and hsp70 levels. Hsp60 was not observed to vary significantly in the face of changing environmental variables, and as such no correlation could be made between serum hsp60 levels and environmental variables in bears. Serum hsp70 was observed to change significantly in response to environmental variables in both polar and grizzly bears. These data along with the changes in cortisol and other health based indicators have the potential to make hsp70 a useful indicator of altered health status in bears. This study is the first attempt to integrate the usefulness of a suite of serum indicators of stress as a tool for detecting the health status of bears. The lack of a control group for comparison to wild population limits the utility of the observed variables as a tool to detect stressed states in bears. However, as these serum indicators are also modulated by the animals health life-history, including food limitation, the monitoring of these serum stress indicators, along with other indicators of fed and fasted states, may give a better picture of the health status of the animal related to nutrient availability.
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Vojáčková, Jana. « Prostorová aktivita medvěda hnědého (Ursus arctos Linnaeus, 1758) v zoologické zahradě ». Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-306067.
Texte intégralRésumé :
This dissertation deals with monitoring of European brown bears behavior (Ursus arctos arctos), namely of males Pišta, Miky and Honzík and of female Eliška in zoological garden in Plzen in spring 2012. Behaviour of all European brown bears is for better clarity presented in the form of tables and graphs. The dissertation includes overview of all kinds of ursine (size, environment, food and reproduction). Key words: bear, hibernation, bears activity
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Bojarska, Katarzyna. « Trophic ecology of the brown bear : from biogeographical to individual point of view ». Praca doktorska, 2015. http://ruj.uj.edu.pl/xmlui/handle/item/42931.
Texte intégral
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Bellemain, Eva. « "Genetics of the Scandinavian brown bear (Ursus arctos) : implication for biology and conservation" ». Phd thesis, 2004. http://tel.archives-ouvertes.fr/tel-00122944.
Texte intégralRésumé :
Cette thèse traite de l'application de l'outil moléculaire pour la gestion, la conservation et la compréhension de la biologie et du comportement des espèces animales. Nous avons étudié l'ours brun (Ursus arctos) en tant qu'espèce modèle et la population d'ours bruns de Scandinavie en tant que cas d'étude. La première partie de cette thèse est une partie méthodologique, dans laquelle nous avons développé des aspects techniques en biologie moléculaire et en analyse de parenté. La seconde partie concerne l'application de ces outils moléculaires pour estimer les tailles de population et comprendre les systèmes d'appariement.Les méthodes non invasives sont de plus en plus utilisées en génétique des populations car elles ne nécessitent pas la manipulation ni le dérangement de l'animal étudié et sont particulièrement recommendabls pour l'étude des populations en danger d'extinction. Cependant, l'ADN extrait de ce type d'échantillons, tels que poils ou fèces, est en général dégradé et/ou en faible quantité, ce qui peut conduire à des erreurs de génotypage. Dans le but d'accroître la qualité et quantité de l'extrait d'ADN, nous avons mis au point une métode PCR (polymerase chain reaction) en deux étapes (“multiplex pre-amplification”). Cette méthode a été testée sur différentes espèces et, en comparaison avec une approche PCR conventionnelle, a permis d'améliorer l'amplification d'ADN et de diminuer le taux d'erreur. Pour amplifier plus spécifiquement l'ADN à partir d'échantillons non invasifs d'ours brun, nous avons également défini de nouvelles amorces microsatellites ainsi qu'un marqueur de sexe spécifique, et combiné une PCR en nid avec la méthode “multiplex pre-amplification”. Ces nouvelles approches peuvent être transposées à d'autres espèces pour lesquelles les méthodes conventionnelles ne sont pas appropriées à cause d'une faible quantité/qualité d'ADN.
Les erreurs de génotypage sont un sujet « tabou » dans les études de génétique des populations, malgré leur incidence dans la plupart des jeux de données et le biais qu'elles peuvent causer dans l'interprétation des résultats. Nous avons considéré quatre cas d'étude représentant une large variété d'investigations en génétique des populations, pour détecter les erreurs de génotypage et identifier leurs causes. Dans ces jeux de données, le taux d'erreur estimé variait de 0.8% à 2.6% , selon l'organisme étudié et le marqueur utilisé. Les sources d'erreur principales étaient les pertes d'allèles pour les microsatellites et les différences d'intensité de pics pour les AFLP (Amplified Fragment Length Polymorphism), ainsi que des erreurs d'origine humaine dans les deux cas. Nous présentons des suggestions pour limiter et quantifier les erreurs de génotypage à chaque étape du processus et recommandons le report systématique du taux d'erreur dans les études de génétique des populations.
Les analyses de parenté basées sur les génotypes multilocus sont largement utilisées pour estimer les succès reproducteurs, les appariements et la fitness dans les populations naturelles. Les approches proposées sont basées sur des estimations du maximum de vraisemblance ou des inférences Bayésiennes et restent en général assez théoriques et difficiles à appliquer pour les biologistes. Il existe un réel manque de logiciels capables de considérer plusieurs générations d'individus et permettant la détermination des deux parents sans hypothèse à priori. Le logiciel PARENTE, que nous avons développé, détermine les maternités, paternités ou les deux parents simultanément, basé sur la compatibilité des génotypes multilocus (marqueurs diploïdes codominants) et des dates de naissance et de mort des individus (si disponibles). Ce logiciel calcule également la probabilité de parenté à partir des fréquences alléliques, du taux d'échantillonnage de la population et du taux d'erreur de génotypage.
Les estimations de taille de population sont essentielles pour la bonne gestion et conservation des espèces. Cependant, de manière générale, peu d'études évaluent la précision des estimations obtenues. Nous avons, dans un premier temps, comparé quatre estimateurs de taille de population, basés sur des méthodes génétiques non invasives. Deux méthodes utilisaient des indices de raréfaction et deux étaient basées sur des estimateurs de capture-marquage-recapture (CMR). Au total, 1904 fèces d'ours bruns ont été collectés sur deux années consécutives sur le terrain (49 000-km2 en Suède centrale). Les estimations variaient de 378 à 572 ours en 2001 et de 273 à 433 ours en 2002, selon l‘estimateur utilisé. La détermination d'une taille de population minimale obtenue à partir de données de radio-télémétrie nous a permis de conclure que l'estimation donnée par une des méthodes de CMR était la plus précise. Cet estimateur incluait une hétérogénéité et une variation temporelle dans les probabilités de détection, ce qui paraissait réaliste dans notre échantillonnage. Deuxièmement, nous avons évalué la fiabilité de trois méthodes de terrain traditionnelles en comparaison avec la méthode génétique la plus performante, dans une aire d'étude plus réduite (7 328-km2). Les trois méthodes de terrain tendaient à sous-estimer la taille de population ; la méthode génétique paraissait être la plus exacte. Nous avons conclu qu'environ 550 (482-648) ours étaient présents dans l'aire de 49 000-km2 et 223 (188-282) ours étaient présents dans l'aire de 7 328-km2. Nous suggérons que la population d'ours a atteint une densité de saturation dans l'aire centrale et disperse à présent sur les bords de cette aire centrale. Une analyse en termes de coûts/bénéfices a démontré que la méthode génétique était moins onéreuse que la méthode de terrain la plus fiable. De plus, elle est préférable d'un point de vue éthique. En conclusion, nous recommandons l'utilisation de méthodes génétiques basées sur un principe de CMR, pour estimer les tailles de population sur de larges aires. Nous insistons sur l'importance d'un effort d'échantillonnage adéquat et, en cas d'échantillonnage biaisé, nous conseillons le calibrage avec des estimations indépendantes, si possible. Nous recommandons La collecte d'un nombre d'échantillons supérieur de 2,5 à 3 fois le nombre « présumé » d'animaux. Ces études ont également confirmé que la gestion actuelle de la population d'ours a été bénéfique et que cette population est actuellement dans un bon statut de conservation.
La connaissance des systèmes d'appariement est importante dans la compréhension de la sélection naturelle. Nous avons étudié deux aspects majeurs du système d'appariement de l'ours brun : les stratégies d'appariement employées par les deux sexes en relation avec l'infanticide sexuellement sélectionné (SSI) et la sélection du partenaire par la femelle. L'infanticide, le meurtre de jeunes non sevrés, peut être considéré comme sexuellement sélectionné si les trois conditions suivantes sont réunies : i) l'infanticide réduit le délai du prochain oestrus de la femelle ; ii) le mâle commettant l'infanticide n'est pas le père des jeunes tués ; iii) le mâle commettant l'infanticide produit la portée suivante de la femelle. Nous avons documenté huit cas d'infanticide sur le terrain. A partir d'observations et d'échantillons collectés sur sites, nous avons vérifié que les trois conditions pour le SSI étaient vérifiées. Cela suggère que le SSI pourrait être une stratégie adaptative pour le mâle chez ce carnivore non social. Contrairement aux espèces sociales où les mâles immigrants tuent les jeunes, la plupart des mâles commettant l'infanticide étaient résidents chez les ours scandinaves. Ceci implique qu'ils sont capables de différencier leurs propres jeunes des jeunes non apparentés, probablement en reconnaissant les femelles avec lesquelles ils se sont accouplés l'année précédente. De plus, nous avons démontré génétiquement un minimum de 14.5% de paternités multiples (28% pour les portées de 3 jeunes ou plus). La promiscuité des femelles, dans le but de confondre les paternités, pourrait donc être une contre-stratégie adaptative pour éviter le SSI. D'autre part, nous avons évalué sur quels critères les femelles ours bruns sélectionnaient leur partenaire reproductif. Nous avons émis l'hypothèse que les femelles pourraient faire face à un dilemme: soit choisir un partenaire de bonne qualité d'un point de vue phénotypique, comme suggéré par les théories de choix du partenaire, soit s'accoupler avec des mâles susceptibles de commettre l'infanticide l'année suivante, c'est à dire les plus proches géographiquement. Nous avons conclu que les femelles sélectionnaient significativement les mâles les plus proches mais aussi les plus hétérozygotes, les plus gros et les plus âgés. Nous suggérons que les femelles ours s'accouplent avec les mâles les plus proches comme contre-stratégie au SSI et exercent un choix post-copulatoire du partenaire reproducteur, basé sur des critères morphologiques tels qu'une large taille corporelle, ou sur des critères de statut de dominance, reflétant la qualité génétique du mâle.
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Christensen, Jennie R. « Factors affecting persistent organic pollutant (POP) accumulation in British Columbia grizzly bears (Ursus arctos horribilis) ». Thesis, 2008. http://hdl.handle.net/1828/890.
Texte intégralRésumé :
This thesis characterizes major factors influencing the accumulation of polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides, and polybrominated diphenyl ethers (PBDEs), in grizzly bears.
Dietary differences among grizzly bears have significant implications for contaminant concentrations and patterns. While salmon-eating bears were dominated by lipophilic PCBs, OC pesticides, and lower-brominated PBDEs, non-salmon-eating bears were dominated by the more volatile PCBs and OC pesticides and higher-brominated PBDEs (e.g. BDE-209). Overall, the ocean-salmon-bear pathway appeared to preferentially select for those contaminants with an intermediate log Kow ~6.5, with salmon delivering up to 70% of OC pesticides, 85% of PBDEs and 90% of PCBs to grizzly bears.
Fat utilization by grizzly bears during hibernation results in significant contaminant concentration increases in residual fat (“concentration effect”). Overall, total PCBs increased by 2.21 times from pre- to post-hibernation, and total PBDEs by 1.58 times. Interestingly, the patterns of the two distinct pre-hibernation grizzly bear feeding ecologies (salmon- and non-salmon-eating) converged during hibernation, suggesting that shared metabolic capacities drive POP patterns during hibernation.
Relative to salmon, grizzly bears have extremely low biomagnification factors (BMFs) for PCBs (0.147), compared to other marine mammals. Low BMF values were a result of >90% depuration (loss) of PCBs through contaminant metabolism and excretion. The results suggest that grizzly bears only metabolize PCB congeners with meta- and para- vicinal hydrogen (H) atoms, suggesting that they have active cytochrome (CYP) P450 2B/3A-like metabolic enzymes. However, congeners structurally resistant to metabolic biotransformation, and those with ortho- and meta- vicinal H atoms, were not readily metabolized, but rather were lost through excretion. This was evidenced by a significant relationship between total retention (Rtotal) of those congeners and log Kow, as well as a lack of change in that relationship during hibernation.
Vegetation and the terrestrial food web were dominated by PBDEs and volatile OC pesticides and PCBs, while salmon and the marine food web were dominated by lipophilic PCBs and OC pesticides, mirroring patterns in grizzly bears within their respective food web. Following consumption of these various foods by the grizzly bears, fecal material closely resembled food in contaminant pattern, suggesting that many of the contaminants may go unabsorbed.
While previous work identified major factors (e.g. age, sex, diet) influencing POP behaviour in wildlife and food webs, this research highlights the need to refine our ideas about those factors in order to better assess chemical health risk in wildlife by considering: 1) individual differences in feeding behaviour; 2) integrated dietary histories (temporal changes); 3) unique biological traits affecting POP fate; 4) modes of POP loss other than metabolism; 5) selection of the most recalcitrant congener for more robust analysis of POP behaviour; 6) use of non-invasive techniques to study diet and POP exposure; and, 7) tissue residue guidelines underestimate health risks. Our results also suggest that PBDEs show POP-type characteristics as defined under the Stockholm Convention, and thus should be regulated.
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Barbosa, Ana Rute Silva. « Landscape effects on gene flow of the Brown bear (Ursus arctos) on the Cantabrian Mountains ». Master's thesis, 2021. http://hdl.handle.net/10773/33533.
Texte intégralRésumé :
As one of the smallest populations in Europe, the Cantabrian brown bear population is threatened, isolated and fragmented in two subpopulations. Despite the low connectivity between both subpopulations, the Cantabrian brown bear population has been recovering over the years and is the only one in Europe that has not been subject to populations reinforcements. However, a difference in the recovery rates has characterizes these two subpopulations (Western and Eastern) over the years. Understanding the environmental features that may be shaping the ecological characteristics of the subpopulations in the Cantabrian range, such as patterns of gene flow along their distribution, are of extreme importance for their conservation and recovery. In this study, microsatellites (nuclear autosomal markers and sex markers) were used to investigate the genetic structure of subpopulations. This analysis was carried out by assessing the correlation between genetic differences and landscape resistance models. Several functional relationships between genetic distances, land cover, temperature, elevation and human disturbance were also analyzed, thus testing for isolation by resistance (IBR) within each subpopulation. Additionally, isolation by distance (IBD) within each population was tested. All hypotheses were tested according to the reciprocal causal modelling method. Results show that agriculture/pastures (hyp2), agriculture/pastures + open areas (hyp13) and forest + agriculture/pastures (hyp9) were the supported landscape resistance models by reciprocal causal modelling, applied in each subpopulation. In the Western subpopulation hyp13 demonstrate the highest relative support (0.040441), and the model contained in this hypothesis was considered as the best. Gene flow in Western subpopulation is maximum in agriculture/pastures + open areas (Agr+Open) whereas in Eastern subpopulation is maximum in forest + agriculture/pastures (Forest+Agr). Western brown bears are dependent of ecosystems where agricultural, pasture and open areas covers are predominant. Eastern brown bears are dependent of ecosystems where forested, agricultural and pasture covers are most prominent. This study reveals a difference between the features that are drivers to gene flow in both subpopulation and provides new insights on the patterns of gene flow in the Cantabrian brown bear subpopulation. Conservation strategies are important to ensure the subpopulations viability and results obtained here will assist in the definition of new measures, thus promoting a more effective recovery of the threatened Cantabrian Mountain population.Sendo uma das populações mais pequenas da Europa, a população Cantábrica de urso pardo encontra-se ameaçada, isolada e fragmentada em duas subpopulações. Apesar da baixa conectividade entre ambas as subpopulações, a população Cantábrica de urso pardo tem vindo a recuperar ao longo dos anos, sendo a única na Europa que não foi alvo de reforços populacionais. Contudo, uma diferença nos ritmos de recuperação tem caracterizado estas duas subpopulações (Ocidental e Oriental) ao longo dos anos. Compreender as características ambientais que podem estar a moldar as características ecológicas das subpopulações da cordilheira Cantábrica, como os padrões de fluxo genético ao longo da sua distribuição, são de extrema importância para a sua conservação e recuperação. Neste estudo, para a investigação da estrutura genética das subpopulações foram utilizados microssatélites (marcadores nucleares autossómicos e marcadores sexuais). Essa análise foi realizada através da avaliação da correlação entre as diferenças genéticas e modelos de resistência da paisagem. Foram ainda analisadas várias relações funcionais entre distâncias genéticas, cobertura de solo, temperatura, elevação e perturbação humana, testando assim o isolamento por resistência (IBR) dentro de cada subpopulação. Adicionalmente foi testado o isolamento por distância (IBD) dentro de cada população. Todas as hipóteses foram testadas segundo o método de modelação causal recíproca. Os resultados demonstram que áreas agrícolas/pastagem (hyp2), áreas agrícolas/pastagem + áreas abertas (hyp13), e áreas de florestas + áreas agrícolas/pastagem (hyp9) foram os modelos de resistência à paisagem suportados pela modelação causal recíproca, aplicada em cada subpopulação. Na subpopulação Ocidental, hyp13 demostrou maior suporte relativo (0.040441), sendo o modelo contido nesta hipótese considerado como o melhor. O fluxo genético da subpopulação Ocidental é máximo nas áreas agrícolas/pastagem + áreas abertas (Agr+Open), enquanto que na subpopulação Oriental este é máximo em áreas de florestas+ áreas agrícolas/pastagem (Forest+Agr). Os ursos ocidentais são dependentes de ecossistemas onde o coberto predominante são as áreas agrícolas, pastagem e áreas abertas. Os ursos orientais são dependentes de ecossistemas onde o coberto proeminente é composto por áreas de floresta, agrícolas e de pastagem. Este estudo revelou uma diferença entre as características que atuam como promotoras do fluxo genético em ambas as subpopulações e providencia novas perspetivas sobre os padrões de fluxo genético na população de urso-pardo da Cantábria. As estratégias de conservação são importantes para assegurar a viabilidade das subpopulações e os resultados aqui obtidos iram auxiliar na definição de novas medidas, promovendo assim uma recuperação mais efetiva da ameaçada população da cordilheira Cantábrica.
Mestrado em Ecologia Aplicada
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CONTI, JACOPO. « Evolution of cranio-dental features and distribution of brown bear (Ursus arctos L., 1758) in Europe ». Doctoral thesis, 2019. http://hdl.handle.net/11573/1240525.
Texte intégralRésumé :
The study of the fossil remains of the brown bear (Ursus arctos, L. 1758) of the Pleistocene has always been extremely interesting for the vertebrate paleontologists. The discovery of bear material in different sites (fluvio-lacustrine and cave deposits), and the study of the various ecological adaptations developed in conjunction with the speloid forms (Ursus deningeri Reichenau, 1906, Ursus spelaeus Rosenmǖller, 1794) has been crucial for the achievement of palaeoecological necessary schemes for the reconstruction of the European paleoterritory.
However, most of the oldest specimens (Middle and Early Pleistocene), presents uncertain taxonomical attribution, making the origin and paleodistribution of the brown bear in Europe still unclear, just like its first occurrence in Italy (Azzaroli, 1983; Rabeder, Pacher, & Withalm, 2010; Wagner, 2010). Similarly, regarding the Late Pleistocene, the relative scarcity of fossil brown bear material in comparison with those of cave bear, and the poor presence of international scientific documentation, often make the morphological distinction between the two evolutionary lines very complicated, especially regarding the Italian territory.
Currently, the brown bear is unequally distributed throughout Europe; in Italy two distinct populations are present, one in the Alps (Ursus arctos arctos L. 1758) and another which is endemic of the Central Apennine region (Ursus arctos marsicanus, Altobello 1921).
The latter, given its peculiar morphological characteristics of the skull (similar to those of the speleoid forms), has been the subject of many studies. However, we do not have a clear framework about the dynamics of its isolation or its origin (Colangelo, et al., 2012; Meloro, Guidarelli, Colangelo, Ciucci, & Loy, 2017; Benazzo, et al., 2017).
The work carried out during the thesis include: i) the census of the Italian and European material of U. arctos; ii) the analysis of most of the Italian and European fossil and sub-fossil specimens through the use of traditional methodologies (morphological description and biometric analysis); iii) the use of new technologies (axial tomography and digitization of the material through photogrammetry) applied to the analysis of two-dimensional and three-dimensional geometric morphometry.
From the results obtained it has been possible to partially review the systematic position of the species U. etruscus, which would no longer be considered as common ancestor of both the arctoid and speloid lineages in Europe, (Zapfe, 1948; Mazza & Rustioni, 1994). Consequently, the arctoid form entered in Europe during various moments throughout the Quaternary, sharing the territory with U. deningeri first and U. spelaeus later.
Other results show morphological patterns which allow to distinguish these two evolutionary lines, especially in the dental elements and in the brain, although some common features of the skull persist.
Finally, from the study of the specimens from the central-southern Italian area, the first occurrence of U. arctos in Italy at Fontana Ranuccio (Lazio) has been highlighted, and the absence of U. arctos marsicanus features within the fossil record have been reported. Therefore, from the morphological analysis, the split between the two Italian populations should be occurred after the dating of the most recent site studied, the Gran Carro deposit (late Bronze Age / early Iron Age).
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Udoni, Makala. « A taphonomic study of black bear (Ursus americanus) and grizzly bear (U. arctos) tooth marks on bone ». Thesis, 2019. https://hdl.handle.net/2144/38728.
Texte intégralRésumé :
Tooth mark and gnaw damage modifications on bone from African carnivores have been extensively examined; however, there are little data on North American carnivores, especially on ursids. Tooth mark modifications include pits, punctures, scores, and furrows, while gnaw damage modifications include crenellated margins, edge polish, scalloping, scooping, and crushed margins. Forensically, tooth mark identification and measurements allow for easier identification of species involved in cases containing predator or scavenger alteration. The present study hypothesized that black bear (Ursus americanus) and grizzly bear (U. arctos) tooth marks will be able to be distinguished from one another and the two bear species will have different gnawing patterns. Further, the study hypothesized that ursid tooth marks and gnaw damage will be distinguishable from other documented carnivore alterations.
In the present study, black bears and grizzly bears from the Oakland Zoo were fed 56 proximal and distal femoral epiphyses from cattle (Bos taurus). The skeletal remains were cleaned and analyzed at Boston University, School of Medicine for pits, punctures, scores, and furrows. Each tooth mark was photographed and then processed through the open-source software ImageJ (National Institutes of Health) in order to obtain the area, perimeter, length, and width of each tooth mark. The presence of certain gnaw damage characteristics were also recorded for each bone, such as crenellated margins, edge polish, scalloping, scooping, and deep furrows. Statistical analyses were used to distinguish if the epiphysis type (proximal or distal) or bear species were statistically significant factors in the type of tooth mark and gnaw damage.
The results indicate a pattern distinctive to ursid scavenging with pits with an average length of 3.53 mm and width of 2.19 mm, an average score width of 1.47 mm, scalloping on the distal epiphysis especially on the patellar surface of the femur, scooping on the proximal epiphysis especially on the greater trochanter of the femur, and deep furrows primarily on the distal epiphysis along the patellar region and condyles of the femur. When comparing the present study to previous ursid studies (Arilla et al. 2014; Domínguez-Rodrigo and Piqueras 2003; Sala and Arsuaga 2013; Saladié et al. 2011) and previous other carnivore studies (Andrés et al. 2012; Delaney-Rivera et al. 2009; Pobiner 2007), there was a statistical significance between ursid pits and fox (Vulpes vulpes), skunk (Mephitis mephitis), and the combination of hyena (Crocuta crocuta) and lion (Panthera leo) pits. Scooping occurred in 35.2% of the entire sample, while scalloping occurred in 29.6% of the entire sample. Scooping has been observed in previous research but not as high of a percentage as the present study, and scalloping has been noted in a black bear study (Carson et al. 2000) and a wolf/dog study (Milner and Smith 1989), but with no numerical data for comparison. The high percentage of scooping and scalloping on long bones could be distinctive characteristics of ursid gnaw damage and could distinguish ursid scavenging from other carnivores.
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Bourbonnais, Mathieu Louis. « Spatial analysis of factors influencing long-term stress and health of grizzly bears (Ursus arctos) in Alberta, Canada ». Thesis, 2013. http://hdl.handle.net/1828/4909.
Texte intégralRésumé :
A primary focus of wildlife research is to understand how habitat conditions and human activities impact the health of wild animals. External factors, both natural and anthropogenic that impact the ability of an animal to acquire food and build energy reserves have important implications for reproductive success, avoidance of predators, and the ability to withstand disease, and periods of food scarcity. In the analyses presented here, I quantify the impacts of habitat quality and anthropogenic disturbance on indicators of health for individuals in a threatened grizzly bear population in Alberta, Canada.
The first analysis relates spatial patterns of hair cortisol concentrations, a promising indicator of long-term stress in mammals, measured from 304 grizzly bears to a variety of continuous environmental variables representative of habitat quality (e.g., crown closure, landcover, and vegetation productivity), topographic conditions (e.g., elevation and terrain ruggedness), and anthropogenic disturbances (e.g., roads, forest harvest blocks, and oil and gas well-sites). Hair cortisol concentration point data were integrated with continuous variables by creating a stress surface for male and female bears using kernel density estimation validated through bootstrapping. The relationships between hair cortisol concentrations for males and females and environmental variables were quantified using random forests, and landscape scale stress levels for both genders was predicted based on observed relationships. Low female stress levels were found to correspond with regions with high levels of anthropogenic disturbance and activity. High female stress levels were associated primarily with high-elevation parks and protected areas. Conversely, low male stress levels were found to correspond with parks and protected areas and spatially limited moderate to high stress levels were found in regions with greater anthropogenic disturbance. Of particular concern for conservation is the observed relationship between low female stress and sink habitats which have high mortality rates and high energetic costs.
Extending the first analysis, the second portion of this research examined the impacts of scale-specific habitat selection and relationships between biology, habitat quality, and anthropogenic disturbance on body condition in 85 grizzly bears represented using a body condition index. Habitat quality and anthropogenic variables were represented at multiple scales using isopleths of a utilization distribution calculated using kernel density estimation for each bear. Several hypotheses regarding the influence of biology, habitat quality, and anthropogenic disturbance on body condition quantified using linear mixed-effects models were evaluated at each habitat selection scale using the small sample Aikake Information Criterion. Biological factors were influential at all scales as males had higher body condition than females, and body condition increased with age for both genders. At the scale of most concentrated habitat selection, the biology and habitat quality hypothesis had the greatest support and had a positive effect on body condition. A component of biology, the influence of long-term stress, which had a negative impact on body condition, was most pronounced within the biology and habitat quality hypothesis at this scale. As the scale of habitat selection was represented more broadly, support for the biology and anthropogenic disturbance hypothesis increased. Anthropogenic variables of particular importance were distance decay to roads, density of secondary linear features, and density of forest harvest areas which had a negative relationship with body condition. Management efforts aimed to promote landscape conditions beneficial to grizzly bear health should focus on promoting habitat quality in core habitat and limiting anthropogenic disturbance within larger grizzly bear home ranges.Graduate
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mathieub@uvic.ca
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DE, ANGELIS DANIELE. « Moving in a crowded world : ecological and human-related factors affecting brown bear (Ursus arctos) space-use patterns ». Doctoral thesis, 2019. http://hdl.handle.net/11573/1231370.
Texte intégralRésumé :
Under the current scenario of human expansion and land-use change, one resource emerges as being particularly disputed between humans and other wildlife species: space. The spatiotemporally detailed and real-time nature of Global Positioning System (GPS) tracking data supports the use of tagged animals as in situ sensors of the environment, to document how ongoing changes are affecting species’ distribution and ecological function. Large carnivores are particularly susceptible to disturbance from infrastructure development, and can represent a promising case study to investigate the effects of human expansion on species spatial ecology at multiple levels, spanning from patch- to landscape scales. I investigated space-use patterns in a south-eastern European population of brown bears (Ursus arctos), whose distribution is shared among more than five countries, from Slovenia to Northern Greece, with its core area located between Slovenia and Croatia. In the first chapter, I investigated ecological and human-related effects on home range size and inner configuration of Dinaric brown bears (Ursus arctos) contrasting two areas, one located in the North (n= 5 bears, 1 females, 4 males) and one in the South (n= 5 bears, 2 females, 3 males), which differed in terms of road and human density, as well as in the availability of supplementary feeding sites. I used Brownian bridge movement models (BBMMs) to estimate circadian and seasonal home ranges and I used linear mixed-effect models (LMM) to investigate the effects of gender, time of the day, season and study area on home range size. Using an individual- based method, I also depicted seasonal core areas and used Environmental Niche Factor Analysis (ENFA) to assess if the internal configuration of seasonal home ranges changed among study areas. Although we failed to find a sex effect on home range size, time of day was an important predictor of home range size, with nocturnal home ranges larger (103.3 km2 72.8) than diurnal ones (62.3 km2 16.6). Then, I detected a seasonal effect on home range size, but this was limited to areas where bears had relatively lower accessibility to artificial feeding sites. Where densities of roads, human settlements, and artificial feeding sites were the highest, selection of core areas by bears was characterized by avoidance for anthropogenic features. Overall, this study revealed that even within the same population range, bears can show behavioural plasticity and adapt to local conditions of human disturbance. Although behavioural plasticity may contribute to ensure carnivore persistence in human-dominated areas, the changes in home range patterns that we detected can also be a warning sign of environmental degradation. The aims of chapter II were i) to classify individual movement patterns of brown bears indicating frequency, period, duration and length of inter-seasonal range movements; ii) to assess the main environmental descriptors within the pre-migratory and post-migratory ranges, as compared to the average habitat conditions in our study area; iii) to identify main differences in bear habitat use during pre-migratory and post-migratory phases. I classified individual movement patterns by means of non-linear Net Squared Displacement (NSD) models. By means of canonical Overlying Mean Index analysis (OMI), I identified habitat descriptors of pre- migratory and post-migratory ranges at the landscape scale. I then quantified the strength of variation in bear habitat use at summer versus fall ranges using a latent selection difference analysis (LSD), at both the population and the individual level. My findings revealed that 6 out of 12 individuals showed facultative and partial seasonal migrations between disjointed seasonal ranges, in contrast to the other bears that remained resident or nomadic throughout the year. Migratory patterns were markedly seasonal, with all departures occurring between mid-September and mid- October (median= 19th September), and returns occurring before the wintering period (median= 18th November). Migratory movements connected seasonal ranges up to >40 km apart (mean = 28.9 km). Most bears migrated from areas characterised by coniferous and mixed forests to lower areas with high proportion of deciduous forest, forest edge and shrubs. Compared to pre-migratory ranges, within migration ranges bears increased both their distance to anthropogenic structures (i.e. paved roads, settlements, artificial feeding sites, cultivated lands) and their selection for highly productive areas (i.e. deciduous forest, forest edge and shrubs). Due to lack of data on fine-scale forest productivity and on human disturbance within bear ranges, the ultimate cause that triggered the observed bear migrations remains to be assessed. However, our findings represent a remarkable contribute that improved our understanding of the species ecology, as migration patterns such as those observed in our study have never been observed before in any other bear population in Europe. In chapter III, I investigated habitat selection on a seasonal basis for 11 individuals (4 females and 7 males), focussing the analysis on bears that did not perform seasonal migrations. In particular, I investigated seasonal changes in bear use/avoidance of human infrastructures such as highway, paved roads, railway, forest roads, human settlements and supplementary feeding sites. The general working hypothesis of this chapter was that bears might display stronger avoidance towards our proxies of human disturbance during periods of increased hunting pressure (i.e. spring and fall). To confirm my hypothesis, we focussed on non-migrating individuals to first exploring general patterns of seasonal habitat selection using k-select analysis, aimed at identifying the principal components of bear seasonal habitat preferences accounting for individuals. In a second phase, I have used resource selection functions (RSF) in a use/available design to compare habitat conditions that were available to bears within their home ranges to habitat that bears used (i.e. at GPS locations). In agreement with my hypothesis, the k-select analysis showed a common pattern of habitat selection during spring and fall for the quasi-totality of individuals, characterized by avoidance to forest roads and selection for areas more hardly reachable by humans (i.e. slopes). Conversely, during summer, bears showed more heterogeneous patterns of habitat selection, reflecting higher individual variability in habitat selection for this period of the year. The results of the RSF analysis confirmed these patterns more thoroughly, with distance to forest roads (spring= 0.33 0.01; fall = 0.30 0.04) and use of slopes (spring= 0.12 0.01; fall = 0.20 0.02) playing a major role in defining bear habitat selection during both periods when hunting was open, and a significant use of supplementary food (i.e. decreased distance from artificial feeding sites) during hyperphagia season (fall = -0.30 0.04). Overall, my findings suggest that hunting might be perceived by bears as a form of predation risk that forces them to increase their concealment, influencing within- home-range habitat use and distribution of the individuals. In chapter IV, I developed a modelling approach to simulate bear movements among suitable resource patches, integrating classical habitat selection studies and cutting-edge movement algorithms. To this aim, I have used a movement-based modelling approach to project potential corridors connecting summer and fall habitat patches. To model habitat patches associated to intensive habitat use during summer and fall, I used Resource Selection Functions (RSF) based on bear relocations representing stationary behaviour (i.e. feeding or resting). Based on bear trajectories representing bear travelling, I then studied bear response to both natural elements (e.g. terrain topography) and human structures (e.g. roads) during their movements using Step Selection Functions (SSF). After quantifying the effects of each tested landscape feature on bear movements, I modelled a map of landscape permeability to bear movement. Finally, I used a Randomised Shortest Path (RSP) algorithm to project potential bear corridors between summer and fall habitat patches within our study area. According to my findings, bears can successfully travel across sub-optimal habitat to reach suitable patches in the fall, although the presence of anthropogenic structures such as highways, main paved roads, railways, and cultivated fields strongly decreased the probability of bear traveling. Model predictions correlated moderately with the frequency of bears killed by vehicle collisions (range r=0.68-0.79). Overall the degree of inter-patch connectivity was rather high across the study area, with many potential bear paths connecting suitable summer and fall habitat patches. However, we recommend that improvement of mitigation measures should be evaluated at the intersection between modelled corridors and linear infrastructures. Our modelling approach might be applied also to other ecological contexts where habitat fragmentation represents a major threat to the long-term persistence of wide- ranging mammalian populations. Overall, this case study represented an intriguing occasion to assess how recent trends of human development might affect the life history traits of wide-ranging brown bear population.
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« An evaluation of hair cortisol concentration as a potential biomarker of long-term stress in free-ranging grizzly bears (Ursus arctos), polar bears (Ursus maritimus), and caribou (Rangifer tarandus sp.) ». Thesis, 2013. http://hdl.handle.net/10388/ETD-2013-10-1032.
Texte intégralRésumé :
Human-caused ecological change negatively affects the sustainability of many wildlife populations but may be especially challenging for large carnivores and ungulates. Long-term physiological stress may be an important mechanism linking ecological change with impaired health and reduced population performance in these groups. The determination of hair cortisol concentration (HCC) has recently demonstrated potential as a biomarker of long-term stress in humans and domestic animals, and may also represent a practical technique for use in free-ranging wildlife. The objectives of this research program were to: 1) develop and apply an accurate and reliable method for measuring cortisol levels in hair collected opportunistically or remotely from free-ranging grizzly bears (Ursus arctos), polar bears (Ursus maritimus), and caribou (Rangifer tarandus sp.), and 2) to evaluate the utility of HCC as a biomarker of long-term stress (and thus potentially useful conservation tool) in these threatened species.
An enzyme-immunoassay (EIA) based technique for measuring HCC in non-human primates was successfully modified for use with small quantities (5-100 mg) of hair representative of samples which may be obtained through opportunistic (e.g. hunting, research captures, archives) or remote (e.g. barb wire snagging) methods in each species. HCC was determined in 151 free-ranging grizzly bears from Alberta, Canada (mean 2.84 pg/mg, range 0.62-43.33 pg/mg); 185 free-ranging polar bears from southern Hudson Bay, Canada (mean 0.48 pg/mg range, 0.16-2.26 pg/mg); in 12 captive Alaskan caribou (R. t. granti) (mean 2.31 pg/mg, range, 1.57-3.86 pg/mg) and 12 captive reindeer (R .t. tarandus) (mean 2.88 pg/mg, range 2.21-3.40 pg/mg) injected either with adrenocorticotropic hormone (ACTH) or saline; and in 94 free-ranging caribou (R. t. groenlandicus) from West Greenland (mean 2.21 pg/mg, range 0.60-6.90 pg/mg). Factors influencing HCC in each species were then explored including: 1) technical considerations for the prudent use of HCC analysis and 2) potential relationships between HCC, biological traits, health, and prevailing environmental conditions. Evidence revealed in this study suggests that, with further research, this technique may show potential as a practical conservation tool for use in free-ranging grizzly bear, polar bear, and caribou populations.