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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Uso do espaço e seleção de hábitat pelo Mico-Leão-da-Cara-Preta (Leontopithecus caissara) / Space use and habitat selection by the Black-faced Lion Tamarin (Leontopithecus caissara)

Nascimento, Alexandre Túlio Amaral 20 June 2008 (has links)
Comprometida com a compreensão da relação entre hábitat e uso do espaço pelo mico-leão-da-cara-preta (Leontopithecus caissara), esta dissertação se norteia por três perguntas: Diferenças de hábitat entre ilha e continente influenciam o tamanho da área de vida? Há predileção da espécie por alguma classe de vegetação dentro da área de uso? Qual a capacidade suporte em sua área de ocorrência continental, bem como nas áreas potenciais para seu manejo conservacionista? Na tentativa de elucidar essas questões esta dissertação se divide em três capítulos. O primeiro contextualiza o trabalho e a apresenta o estado atual de conhecimento de L. caissara. Os capítulos segundo e terceiro concernem às questões centrais do trabalho - uso e seleção do hábitat pelo mico-leão-da-cara-preta. No capítulo dois apresentamos o uso do espaço pela espécie em sua região continental de ocorrência e comparamos os resultados obtidos com as informações disponíveis para a Ilha do Superagui. No capítulo três tratamos da seleção do hábitat por grupos insulares e continentais de L. caissara e estimamos a capacidade suporte para a espécie considerando seus limites de ocorrência e as áreas passíveis de receber animais em situação de manejo. Ao final desses capítulos apresentamos algumas considerações e recomendações para pesquisa e conservação do mico-leão-da-cara-preta. A preocupação com uma postura crítica e construtiva acerca das metodologias de estudos e análises sobre uso do espaço por espécies animais é transversal aos assuntos tratados ao longo de todo o trabalho. Os resultados apresentados confirmam as grandes áreas de vida de L. caissara, as quais parecem ser compensadas energeticamente pela incorporação de novas áreas e abandono de outras ao longo do tempo. Os tipos de hábitats mais intensamente utilizadas pelos mico-leão-da-cara-preta intercalaram áreas de floresta madura e em clímax edáfico com áreas antropizadas em sucessão, ambos hábitats sobre pouco desnível altimétrico. A capacidade suporte estimada é aparentemente incapaz de sustentar uma população viável e ressalta a urgência de pesquisas genéticas que colaborem para a compreensão do histórico ecológico/evolutivo de L. caissara. Potenciais translocações com vistas ao aumento populacional devem considerar as amplas áreas de diva, a espacialidade dinâmica, a relação uso/disponibilidade do hábitat e as diferenças entre ilha e continente. / This dissertation focuses on the interaction between habitat and space use by the black-faced lion tamarin (Leontopithecus caissara). We seek to answer three questions: 1) Do differences in vegetation between insular and continental habitats influence how the species use the space? 2) Does the species prefer a specific type of vegetation within its home-range? 3) What is the carrying capacity of the continental distribution and which are areas for potential conservation management? The first chapter of this dissertation relates the subjects discussed and introduces what is known about L. caissara. The second and third chapters develop the central questions of the research: the use and selection of habitat by the black-faced lion tamarin. In Chapter Two, we introduce space use by the species in its continental distribution and compare the results with data from Superagui Island. In Chapter Three, we address habitat selection by insular and continental groups of L. caissara and estimate the carrying capacity for the species given its distribution and areas potentially able to receive animals in a management context. The conclusion of each chapter presents considerations and recommendations for research and conservation. The study methods and analyses of space use aim to be critical and constructive and are relevant to the topics addressed throughout the text. The results presented confirm that the large home-ranges of L. caissara undergo dynamic turnovers, with some areas being abandoned and others incorporated throughout the year. The habitat types most intensively used by tamarins include areas of mature and forest mixed with areas of anthropic succession, both occurring at low altitudes. The estimated carrying capacity is apparently insufficient to maintain a viable population and highlights the importance of genetic studies that incorporate the ecological/evolutionary history of the species. Potential translocations meant to increase population size should consider the large home-ranges, dynamic spatial structure, relation of habitat use/availability and the differences between island and continent.
32

Intraspecific variation in environmental and geographic space use : insights from individual movement data

Bonnet-Lebrun, Anne-Sophie January 2018 (has links)
Species’ ranges arise from the interplay between environmental preferences, biotic and abiotic environmental conditions, and accessibility. Understanding of – and predictive models on – species distributions often build from the assumption that these factors apply homogenously within each species, but there is growing evidence for individual variation. Here, I use movement data to investigate individual-level decisions and compromises regarding the different costs and benefits influencing individuals’ geographic locations, and the species-level spatial patterns that emerge from these. I first developed a new method that uses tracking data to quantify individual specialisation in geographic space (site fidelity) or in environmental space (environmental specialisation). Applying it to two species of albatrosses, I found evidence of site fidelity but weak environmental specialisation. My results have implications for how limited research efforts are best-targeted: if animals are generalists, effort are best spent by understanding in depth individual patterns, i.e., better to track fewer individuals for long periods of time; whereas if animals tend to be specialists, efforts should be dedicated to tracking as many individuals as possible, even if for shorter periods. I then investigated individual migratory strategies and their drivers in nine North American bird species, using ringing/recovery data. I found latitudinal redistribution of individuals within the breeding and non-breeding ranges that generally did not follow textbook patterns (‘chain migration’ or ‘leapfrog migration’). Migratory individuals tend to trade off the benefits of migration (better tracking of climatic niche; better access to resources) and its costs (increasing with migratory distance). I found that birds are more likely to remain as residents in areas with warmer winter temperatures, higher summer resource surpluses and higher human population densities (presumably because of a buffering effect of urban areas). Overall, my results highlight the importance of considering individual variation to understanding the ecological processes underpinning species’ spatial patterns.
33

Uso do espaço e seleção de hábitat pelo Mico-Leão-da-Cara-Preta (Leontopithecus caissara) / Space use and habitat selection by the Black-faced Lion Tamarin (Leontopithecus caissara)

Alexandre Túlio Amaral Nascimento 20 June 2008 (has links)
Comprometida com a compreensão da relação entre hábitat e uso do espaço pelo mico-leão-da-cara-preta (Leontopithecus caissara), esta dissertação se norteia por três perguntas: Diferenças de hábitat entre ilha e continente influenciam o tamanho da área de vida? Há predileção da espécie por alguma classe de vegetação dentro da área de uso? Qual a capacidade suporte em sua área de ocorrência continental, bem como nas áreas potenciais para seu manejo conservacionista? Na tentativa de elucidar essas questões esta dissertação se divide em três capítulos. O primeiro contextualiza o trabalho e a apresenta o estado atual de conhecimento de L. caissara. Os capítulos segundo e terceiro concernem às questões centrais do trabalho - uso e seleção do hábitat pelo mico-leão-da-cara-preta. No capítulo dois apresentamos o uso do espaço pela espécie em sua região continental de ocorrência e comparamos os resultados obtidos com as informações disponíveis para a Ilha do Superagui. No capítulo três tratamos da seleção do hábitat por grupos insulares e continentais de L. caissara e estimamos a capacidade suporte para a espécie considerando seus limites de ocorrência e as áreas passíveis de receber animais em situação de manejo. Ao final desses capítulos apresentamos algumas considerações e recomendações para pesquisa e conservação do mico-leão-da-cara-preta. A preocupação com uma postura crítica e construtiva acerca das metodologias de estudos e análises sobre uso do espaço por espécies animais é transversal aos assuntos tratados ao longo de todo o trabalho. Os resultados apresentados confirmam as grandes áreas de vida de L. caissara, as quais parecem ser compensadas energeticamente pela incorporação de novas áreas e abandono de outras ao longo do tempo. Os tipos de hábitats mais intensamente utilizadas pelos mico-leão-da-cara-preta intercalaram áreas de floresta madura e em clímax edáfico com áreas antropizadas em sucessão, ambos hábitats sobre pouco desnível altimétrico. A capacidade suporte estimada é aparentemente incapaz de sustentar uma população viável e ressalta a urgência de pesquisas genéticas que colaborem para a compreensão do histórico ecológico/evolutivo de L. caissara. Potenciais translocações com vistas ao aumento populacional devem considerar as amplas áreas de diva, a espacialidade dinâmica, a relação uso/disponibilidade do hábitat e as diferenças entre ilha e continente. / This dissertation focuses on the interaction between habitat and space use by the black-faced lion tamarin (Leontopithecus caissara). We seek to answer three questions: 1) Do differences in vegetation between insular and continental habitats influence how the species use the space? 2) Does the species prefer a specific type of vegetation within its home-range? 3) What is the carrying capacity of the continental distribution and which are areas for potential conservation management? The first chapter of this dissertation relates the subjects discussed and introduces what is known about L. caissara. The second and third chapters develop the central questions of the research: the use and selection of habitat by the black-faced lion tamarin. In Chapter Two, we introduce space use by the species in its continental distribution and compare the results with data from Superagui Island. In Chapter Three, we address habitat selection by insular and continental groups of L. caissara and estimate the carrying capacity for the species given its distribution and areas potentially able to receive animals in a management context. The conclusion of each chapter presents considerations and recommendations for research and conservation. The study methods and analyses of space use aim to be critical and constructive and are relevant to the topics addressed throughout the text. The results presented confirm that the large home-ranges of L. caissara undergo dynamic turnovers, with some areas being abandoned and others incorporated throughout the year. The habitat types most intensively used by tamarins include areas of mature and forest mixed with areas of anthropic succession, both occurring at low altitudes. The estimated carrying capacity is apparently insufficient to maintain a viable population and highlights the importance of genetic studies that incorporate the ecological/evolutionary history of the species. Potential translocations meant to increase population size should consider the large home-ranges, dynamic spatial structure, relation of habitat use/availability and the differences between island and continent.
34

Sociedade e natureza: A produÃÃo do EspaÃo no entorno da primeira etapa do Parque do Cocà / Society and nature: The production of the Space in entorno of the first stage of the Park of the CocÃ

Francisco Janilson Ferreira Lima 19 September 2007 (has links)
A primeira etapa do Parque EcolÃgico do Cocà e as Ãreas relativas ao seu entorno localizados na porÃÃo sudeste de Fortaleza sÃo dotadas de caracterÃsticas naturais na paisagem, mesmo apÃs terem sofrido intensa urbanizaÃÃo a partir da segunda metade do sÃculo XX. A urbanizaÃÃo transformou um espaÃo caracterizado inicialmente por diversas restriÃÃes à ocupaÃÃo, devido aos obstÃculos naturais presentes, em um dos mais (des)valorizados na cidade. Essa Ãrea foi produzida ao longo desse perÃodo por diversos agentes modeladores do espaÃo, em especial o poder pÃblico no tocante à implementaÃÃo de uma infra-estrutura urbana bÃsica. As aÃÃes beneficiaram diversos segmentos da sociedade, em especial a elite e o segmento empresarial, o que contribuiu para a formaÃÃo de diferentes formas espaciais e diversas formas de agressÃo à natureza. O produto da relaÃÃo da sociedade com a natureza foi a produÃÃo de um espaÃo geogrÃfico singular e Ãnico nos limites territoriais da metrÃpole, uma vez que reÃne de forma compactada problemas de ordem socioeconÃmica e ambiental de grande monta. Tal caracterÃstica o torna ainda um espaÃo cheio de contrastes e contradiÃÃes, diante da variedade e complexidade das diversas formas de uso e ocupaÃÃo do solo, sejam elas para fins de moradia, comÃrcio, serviÃos e lazer. Ao analisar esse espaÃo à possÃvel verificar grupos minoritÃrios, representados por uma elite econÃmica e/ou polÃtica, com facilidade de acesso entre elas. Esse grupo tem nesse espaÃo, Ãvidos interesses de lucro em detrimento do restante da populaÃÃo do entorno. A sociedade, em meio a essa disputa de classes, à a que mais perde devido à reduÃÃo, quanto-qualitativa de seus recursos ambientais. / The first stage of the Ecological Park of the Cocà and located the relative areas to its roundness in the Southeastern portion of Fortaleza are endowed with natural characteristics in the landscape, exactly after to have suffered intense urbanization from the second half from century XX. The urbanization transformed a space characterized initially for diverse restrictions to the occupation, which had to the natural obstacles gifts, in one of more depreciated in the city. This area was produced to long of the this period for diverse agents modellers of the space, in special the public power in the moving one to the implementation of basic an urban infrastructure. The actions had benefited to diverse segments da society, in special the elite and the enterprise segment, the one that contributed for the formation of different space forms and diverse forms of aggression the nature. The product of these social relations on the way was capable to produce a singular and only geographic space in the territorial limits of the metropolis, a time that congregates of compact form problems of great economical-social and environmental order of sum. Such characteristic still becomes it a full space of contrasts and contradictions, ahead of the variety and complexity in moving to the diverse forms of use and occupation of the ground, is they stops ends of housing, commerce, services and leisure. When analyzing this space is possible to verify that minority, however with priority groups, represented for the economic elite and/or politics and with easiness of access between them, they have in this space, eager interests of profit in detriment of the remain of the population of roundness. The society, in way to this dispute of classes, is the one that more loses due to reduction, how much-qualitative of its environmental resources.
35

Space use and habitat selection of the wolf (<em>Canis lupus</em>) in human-altered environment in Finland

Kaartinen, S. (Salla) 23 March 2011 (has links)
Abstract The grey wolf is the most widely distributed of all land mammals and is a habitat generalist that inhabits all the vegetation types of the Northern Hemisphere. Wolves also breed well and have the potential to rapidly expand to new areas. In Finland, the wolf is a game species, and as a result of Finland’s membership of the European Union, the wolf population is subject to very limited hunting due to the obligation to protect the species. Mainly for this reason, the wolf population in Finland has increased significantly in recent years. In particular, the birth rate has developed favourably and the number of litters increased from just four in 1996 to 20 in 2005. It also seems at present that the wolf population in Finland is no longer following the fluctuations in wolf numbers in Russian Karelia. The general aim of this dissertation is to provide applicable knowledge for wolf management and conservation purposes, and especially to examine the effects of human-modified landscapes on wolf population expansion in Finland. Various aspects of habitat selection were investigated in four sub-studies to gain a thorough insight into the space use and habitat needs of wolves. Species data came from a long-term wolf population study that included location information from 85 radio- and GPS-GSM-collared wolves from 1998 onwards, as well as track location data based on about 30 000 annual observations recorded with geographical coordinates by a local network of experts on large carnivores. I found that adaptability makes it possible for the wolf to live in the multiple-use, semi-wild forests of Finland and that no restrictions are imposed by the landscape on wolf population growth and expansion. In general, the results of my dissertation provide evidence that wolves tend to avoid the presence of human influence when establishing a territory and also when selecting their den site. However, as wolf numbers increase, conflict situations will more frequently occur between wolves and humans, although the risk of depredation events, for example among sheep farms, varies between farms in Finland. That is, there are some environmental and farm level factors that are associated with wolf depredation. The breeding wolf population in Finland has gradually expanded and the first litters have recently been born in western Finland after an absence of more than 100 years. The geographical distance to the Scandinavian population is shorter from these new western territories than from the population’s core area in eastern Finland. This could potentially increase the likelihood of dispersal from Finland to Scandinavia. / Tiivistelmä Susi on habitaattigeneralisti, jonka levinneisyys kattaa kaikki pohjoisen pallonpuoliskon kasvillisuustyypit. Sudet myös lisääntyvät hyvin ja voivat näin ollen levittäytyä nopeasti uusille alueille. Suomessa susi on riistalaji, jonka metsästys on rajoitettua Euroopan unionin jäsenyyden myötä. Lähinnä tästä syystä Suomen susikanta on kasvanut voimakkaasti 1990-luvun ja 2000-luvun alun aikana. Erityisesti syntyvyys on kasvanut: pentueiden määrä lisääntyi neljästä 20:een vuosien 1996 ja 2005 välillä. Näyttäisi siltä, ettei Suomen nykyinen susipopulaatio enää seuraa Venäjän Karjalassa tapahtuvia kannanvaihteluita. Väitöskirjan tavoitteena on ollut tuottaa susikannan hoidossa ja suojelussa käytettävissä olevaa tietoa ja erityisesti tutkia susikannan levittäytymistä ihmisen muokkaamassa ympäristössä Suomessa. Neljässä osatutkimuksessa on käsitelty suden habitaatinvalintaa eri näkökulmista, jotta saataisiin kokonaiskuva suden tilankäytöstä Suomessa. Tutkimusaineisto rakentui pitkäaikaisesta seuranta-aineistosta, jota on kerätty vuodesta 1989 lähtien. Vuosien 1989 ja 2010 välillä 85 sutta on pannoitettu radio- tai GPS-GSM –pannalla. Tutkimuksessa käytettiin hyväksi myös noin 30 000 vuosittain tehtyä jälkihavaintoa. Tutkimustulosten perusteella susi selviää hyvin Suomen monikäyttömetsissä, eivätkä maisematyypit itsestään rajoita susipopulaation kasvua ja levittäytymistä. Toisaalta tulokset osoittavat myös sen, että sudet välttelevät ihmistoimintoja valitessaan reviiri- tai pesäpaikkoja. Kuitenkin susien lukumäärän kasvaessa ristiriitatilanteet susien ja ihmisten välillä tulevat lisääntymään, vaikka susivahinkoriskin suuruus vaihteleekin Suomessa huomattavasti. Esimerkiksi lammastilojen susivahinkoriski riippuu sekä ympäristötekijöistä, että tilan sisäisistä tekijöistä. Kaiken kaikkiaan lisääntyvän susipopulaation esiintymisalue on Suomessa vähitellen kasvanut leviten itärajan tuntumasta kohti länttä. Tämän myötä maantieteellinen etäisyys Skandinavian susipopulaatioon on pienentynyt viimeisten vuosien aikana. Tämä voi edesauttaa susiyksilöiden siirtymistä Suomesta Skandinaviaan.
36

A non-native carnivore living in a cultural landscape / Ein gebietsfremder Raubsäuger in der Kulturlandschaft

Zschille, Jana 29 August 2017 (has links) (PDF)
Alongside the destruction of habitat, the impact of invasive alien species (IAS) is considered as one of the most important threats to global biodiversity. Therefore, international directives as well as national legislation call for measures to prevent the further spread of already established IAS as well as to limit their negative effects on native flora and fauna. This study deals with one of these non-native species – the American mink (Neovison vison). In order to get information about ecology and behaviour of this semiaquatic carnivore, a small population in a north German fishpond area, where mink has been spreading since the 1970s, was investigated. During the years 2003 to 2006 data about annual and circadian activity patterns, space use, territorial system as well as feeding habits and their variations during different seasons were collected. For this purpose, altogether 14 individuals (nine males, five females) were monitored using radio-telemetry. Based on the results, the potential impact of American mink on indigenous species was discussed and implications for mink control and management were deduced. American mink are difficult to radio tag. The small difference between their head and neck circumferences mean that the radio collars must be worn tightly to prevent loss. A methodological evaluation of conventional collar transmitters revealed that in six out of eight cases serious skin injuries on the necks were the consequences. Therefore, all radio collars were removed and radio transmitters were surgically implanted in the peritoneal cavity of mink by veterinarians. One male bit open the sutures and died after emergency surgery, but in 13 cases implantation did not affect survival or reproduction of the mink. With reference to animal welfare, intraperitoneal implantation of radio transmitters (in combination with observation and quarantine for several days after operation) instead of external radio collars were recommended for long term telemetry studies of American mink. Analyses of annual activity patterns revealed significant differences in seasonal activity rates. Both sexes reduced their average activity rates in cold winter months (October to February) to about 23 %. This energy-saving strategy is possible because of sufficient food availability, especially of fish, at this time. In March, male as well as female mink considerably increased their activity to almost 40 % due to the mating season. In summer months, during the pup-raising period (May to August), female activity continued to be high (between 40 and 50 %). However, male mink which are not involved in rearing the young, were less active (about 30 %) until July. But in August and September, the time of juvenile dispersal followed by changes in the territorial system and intraspecific aggression, activity rates of males increased again up to 43 %. Circadian activity rhythms differed markedly between sexes. All investigated females exhibited a perennial diurnal pattern. Three of five investigated male mink showed typical nocturnal activity throughout the year. Two males displayed arrhythmic behaviour; they did not prefer any time of the day for activity. On the one hand, gender differences in annual as well as circadian activity patterns of American mink reflect the diversity in ecological constraints, primarily the investment into reproduction. On the other hand, the different temporal strategies of sexes may have the potential to reduce intraspecific, especially intersexual competition. Investigating territorial systems and space use of mink, in comparison to other European studies, relatively large home ranges combined with a quite low population density were observed. In summer months male mink used on average 15.4 km length of waterway and female mink used on average 9.3 km length of waterway. In accordance with the trend of activity rates, male and female mink reduced their large summer home ranges by more than half during the cold winter period. But all-season male mink used significantly larger areas than female mink. High intersexual overlapping rates of home ranges and low levels of intrasexual overlapping of neighbouring home ranges confirm intrasexual territoriality of American mink. Probably, the low population density (0.6-0.7 individuals/km2) allows such high variations in seasonal and sexual home range size. During the mating season males considerably enlarged their home ranges and roamed nearly through the entire study area in search of receptive females. The shifting of stable temporary home ranges observed within one season or between the same seasons of consecutive years demonstrates the highly dynamic nature of spatial behaviour among American mink. The recorded characteristic features of spatial and temporal behaviour should be considered when planning monitoring- and management measures of this invasive carnivore. For instance, the reduced home ranges and activity rates during winter months should be taken into account in mink trapping projects. Analyses of more than 2500 scatsamples of radio tracked mink show that investigated animals principally prey on fish, small mammals and birds (eggs inclusive). There were significant seasonal variations of diet composition. In spring, the three categories of prey - fish, mammals and birds (eggs inclusive) - were hunted in similar amounts. During summer, birds and their eggs made up the main part of the diet followed by mammals. In autumn, the proportion of birds in the mink diet decreased, whereas fish gained in importance. This trend continued during the winter period, when mink preyed almost exclusively on fish. Throughout the entire year amphibians, crustaceans, insects, molluscs and reptiles were found only occasionally in scatsamples. Among birds, the mink preyed mainly on the Eurasian Coot (Fulica atra) followed by the Mallard (Anas platyrhynchos). Mammalian prey was clearly dominated by the water vole (Arvicola terrestris) and among fish, mink hunted especially perch (Perca fluviatilis), roach (Rutilus rutilus) and carp (Cyprinus carpio). Results clearly demonstrate that mink is an opportunistic predator, which hunts its prey according to availability and vulnerability, respectively. Despite the high portions of fish in the autumn and winter diet, the economic damage to fishery caused by mink seems to be low. Perch and roach were preyed on in higher frequencies than the carp which is economically relevant. However, high predation on birds and their eggs during the breeding season indicates a potential negative impact of mink on waterfowl. To summarise, it can be noted that characteristic features of the anthropogenically influenced study area affect feeding habits, activity patterns, space use and density of local mink population. In this regard the management of fishponds, which influences seasonal availability of habitat- and food resources for mink, plays an important role. American mink is regarded as “invasive”, because a negative impact on native species has been proved by several European studies. Consequently, this study recommends management with a focus on effective monitoring and, if necessary, control or exclusion measures adapted to the specific local requirements. Furthermore, to prevent additional introductions into the wild, the still existing farms have to be protected against outbreaks and liberations. In the long term, a general ban on the trade and keeping of American mink would be desirable. / Der Einfluss invasiver, gebietsfremder Arten wird neben der Habitatzerstörung als eine der größten Gefährdungen der Biodiversität weltweit angesehen. Sowohl internationale Umweltvereinbarungen als auch die nationale Gesetzgebung fordern daher Maßnahmen, die eine weitere Ausbreitung bereits etablierter invasiver Neozoen verhindern und deren negative Einflüsse minimieren. Die vorliegende Studie befasst sich mit einer dieser Neozoen - dem Amerikanischen Nerz bzw. Mink (Neovison vison). Um Erkenntnisse zu Ökologie und Verhalten des semiaquatischen Musteliden in Deutschland zu gewinnen, wurden Daten zu tages- und jahreszeitlichen Aktivitätsmustern, zu Raumnutzung und Territorialsystem sowie zur Nahrungswahl und den jahreszeitlichen Unterschieden im Beutespektrum der Art erhoben. Dafür konnten in den Jahren 2003 bis 2006 in einem Fischteich-Gebiet in Mecklenburg-Vorpommern, wo sich Minke bereits seit den 1970er Jahren etabliert haben, insgesamt 14 Individuen (neun Männchen, fünf Weibchen) radiotelemetrisch überwacht werden. Anhand der Ergebnisse wird einerseits der potentielle Einfluss des gebietsfremden Raubsäugers auf einheimische Arten abgeschätzt und diskutiert. Andererseits werden die Ergebnisse herangezogen, um effektive Monitoring- und Managementmaßnahmen abzuleiten. Eine methodische Evaluation von Halsbandsendern zeigte, dass in sechs von acht Fällen die getesteten Halsbänder, die aufgrund des sehr ähnlichen Hals-Kopf-Umfanges der Individuen relativ eng angelegt werden müssen, Hautverletzungen verursachten. Infolgedessen wurden die Halsbandsender gegen durch Tierärzte operativ in die Bauchhöhle eingesetzte Implantationssender ausgetauscht. Auch bei allen nachfolgend gefangenen Tieren wurden die Sender implantiert. Bei insgesamt 14 durchgeführten Erstimplantationen beeinflussten mit Ausnahme eines Falles (Tod durch Aufbeißen der Naht) die Implantate weder das Überleben, noch die Reproduktion der Minke. Daher ist v.a. in Hinblick auf Tierschutzaspekte die Senderimplantation (in Kombination mit einer Mehrtages-Quarantäne) anstatt der Verwendung von externen Halsbandsendern zu empfehlen. Die Analyse der circannuellen Aktivitätsmuster ergab signifikante Unterschiede der saisonalen Aktivitätsraten. Während der kalten Wintermonate (Oktober bis Februar) zeigten beide Geschlechter mit durchschnittlich etwa 23 % eine vergleichsweise geringe Aktivität. Diese energiesparende Verhaltensweise war möglich, da auch im Winter ein ausreichend hohes Nahrungsangebot, vor allem an Fisch, vorhanden war. Im März kam es sowohl bei den Männchen als auch bei den Weibchen zu einem durch die Paarungszeit verursachten, beträchtlichen Anstieg der mittleren Aktivitätsraten auf fast 40 %. In den Sommermonaten (Mai bis August) waren die weiblichen Tiere, durch die Anforderungen der Jungenaufzucht bedingt, anhaltend häufig aktiv (zwischen 40 und 50 %). Die Aktivitätsraten der nicht an der Jungenaufzucht beteiligten Männchen dagegen nahmen im April wieder ab, um bis zum Juli auf einem vergleichsweise geringen Niveau von etwa 30 % zu bleiben. Sie stiegen jedoch während der Monate August und September erneut auf etwa 43 % an. Zu dieser Zeit wandern gewöhnlich die Jungtiere ab und suchen sich ein eigenes Streifgebiet (= Aktionsraum), dadurch kommt es zu Änderungen im Territorialsystem und damit einhergehenden innerartlichen Auseinandersetzungen. Beide Geschlechter unterscheiden sich stark in ihren tageszeitlichen Aktivitätsrhythmen. Alle Weibchen waren ganzjährig tagaktiv. Von den fünf untersuchten Männchen zeigten drei typische Nachtaktivität im gesamten Jahresverlauf. Die beiden anderen männlichen Tiere verhielten sich in ihren Aktivitätsrhythmen indifferent, sie zeigten das ganze Jahr über keine Präferenzen für eine bestimmte Tageszeit. Die geschlechtsspezifischen Unterschiede sowohl in den circannuellen als auch in den circadianen Aktivitätsmustern spiegeln zum einen die verschiedenen Anforderungen an die Geschlechter wieder, vor allem die Investitionen in die Fortpflanzung. Zum anderen können die geschlechtsspezifisch unterschiedlichen Zeitnutzungs-Strategien zu einer Minimierung der innerartlichen, vorzugsweise der intersexuellen Konkurrenz führen. Die Analyse der Telemetriedaten hinsichtlich Raumnutzung und Territorialsystem ergab im Vergleich zu anderen europäischen Studien relativ große individuelle Aktionsräume verbunden mit einer geringen Populationsdichte im Untersuchungsgebiet. So erstreckten sich die durchschnittlich genutzten Sommerstreifgebiete der Männchen auf 15,4 km und die der Weibchen auf 9,3 km Flusslauf bzw. Teichufer. Entsprechend dem Trend der saisonalen Aktivitätsmuster, reduzierten beide Geschlechter ihre großen Sommerstreifgebiete während der Winterhalbjahre um mehr als die Hälfte der Fläche. Allerdings nutzten die Männchen zu allen Jahreszeiten wesentlich größere Aktionsräume als die weiblichen Minke. Große Streifgebietsüberlappungen zwischen den Geschlechtern sowie verhältnismäßig niedrige Überlappungsraten der benachbarten Streifgebiete von Tieren des gleichen Geschlechts bestätigen die intrasexuelle Territorialität der Art. Die erheblichen Unterschiede der saisonalen und geschlechtsspezifischen Aktionsraumgrößen werden vermutlich durch die ermittelte, vergleichsweise geringe Populationsdichte (0,6-0,7 Individuen/km2) ermöglicht. Die ausgedehnte und sich fast über das gesamte Untersuchungsgebiet erstreckende Raumnutzung der Männchen während der Paarungszeit ist durch die Suche nach fortpflanzungsbereiten Weibchen bedingt. Die Raumnutzung der untersuchten Minke unterliegt einer hohen Dynamik, dies wird durch die häufige räumliche Verschiebung temporär stabiler Streifgebiete innerhalb einer Jahreszeit oder auch zwischen den gleichen Jahreszeiten aufeinanderfolgender Jahre verdeutlicht. All diese ermittelten charakteristischen Besonderheiten im Raum-Zeit-Verhalten der Art sollten bei der Entwicklung von Monitoring- und Managementkonzepten berücksichtigt werden. So müssen beispielsweise bei der Fallenjagd im Winter die zu dieser Zeit stark verkleinerten Streifgebiete und die reduzierten Aktivitätsraten Beachtung finden. Die Analyse der über 2500 Losungsproben telemetrierter Minke zeigte, dass sich die untersuchten Tiere hauptsächlich von Fisch, Kleinsäugern und Vögeln (inklusive deren Eiern) ernährten. Dabei traten allerdings signifikante saisonale Unterschiede in der Nahrungs-zusammensetzung auf. So wurden im Frühjahr die drei Beutekategorien Fisch, Kleinsäuger sowie Vögel und deren Eier in ähnlichen Anteilen erbeutet. Während des Sommers bildeten Vögel und Vogeleier die Hauptbeute, gefolgt von Kleinsäugern. Im Herbst verringerte sich der Vogel- und Kleinsäugeranteil im Beutespektrum zugunsten von Fisch. Dieser Trend setzte sich bis in den Winter fort; in dieser Jahreszeit ernährten sich die Minke fast ausschließlich von Fisch. Amphibien, Reptilien, Krebstiere, Insekten und Mollusken wurden im gesamten Jahresverlauf nur gelegentlich gefressen. Innerhalb der Gruppe der Vögel prädierten die Minke vor allem Blässhühner (Fulica atra), gefolgt von Stockenten (Anas platyrhynchos). Das Kleinsäuger-Beutespektrum wurde eindeutig von der Schermaus (Arvicola terrestris) dominiert und unter den Fischen erbeuteten die Minke vorzugsweise Flussbarsche (Perca fluviatilis), Plötzen (Rutilus rutilus) und Karpfen (Cyprinus carpio). Die Ergebnisse der Nahrungsanalyse bestätigen den Mink als einen opportunistischen Prädator, der seine Beutetiere je nach Verfügbarkeit bzw. dem erforderlichen Jagdaufwand nutzt. Trotz des hohen Fischanteils in der Herbst- und Winternahrung ist der durch den Mink verursachte ökonomische Schaden schätzungsweise relativ gering. Flussbarsch und Plötze wurden in höheren Frequenzanteilen erbeutet als der wirtschaftlich relevante Karpfen. Die starke Prädation von Wasservögeln und deren Eiern besonders in den Frühjahrs- und Sommermonaten weist allerdings auf einen potentiell negativen Einfluss des invasiven Raubsäugers auf diese Tiergruppe hin. Zusammenfassend lässt sich festhalten, dass die spezifischen Charakteristika des anthropogen geprägten Untersuchungsgebietes sowohl Nahrungsökologie und Aktivitätsmuster als auch Raumnutzung und Populationsdichte der lokalen Minkpopulation beeinflussen. Eine besondere Rolle hierbei spielt die Bewirtschaftung der Fischteiche, denn vor allem daraus resultiert für die Minke eine saisonal unterschiedliche Verfügbarkeit an Lebensraum und Nahrung. Negative Auswirkungen des Amerikanischen Nerzes auf die einheimische Tierwelt wurden in anderen europäischen Ländern belegt und rechtfertigen die Einstufung dieser Art als „invasiv“. Demzufolge wird in der vorliegenden Arbeit ein Management empfohlen, bei dem der Focus auf einem effektiven Monitoring und gegebenenfalls auf zweckmäßigen, an die lokalen Bedingungen angepassten Fang- oder Abwehrmaßnahmen liegt. Zudem sollten, um einer weiteren Ausbringung in das Freiland vorzubeugen, die wenigen noch existierenden Minkfarmen besser gegen Ausbrüche bzw. Freilassungsaktionen gesichert werden. Langfristig ist ein generelles Besitz- und Vermarktungsverbot für die Art wünschenswert.
37

Die reichstrukturierte Agrarlandschaft - ein unbeachteter Lebensraum für die gefährdete Europäische Wildkatze (Felis silvestris)

Jerosch, Saskia 20 July 2021 (has links)
Seit Ende des 20. Jahrhunderts wird eine Ausbreitung der solitär lebenden und streng geschützten Europäischen Wildkatze (Felis silvestris) registriert, die sich auch aus den bewaldeten Lebensräumen in die weitgehend offene Agrarlandschaft erstreckt. Kenntnisse über Lebensraumansprüche in diesen Landschaftsausschnitten liegen bisher für die Art nicht vor. Ziel der Studie ist es, erstmalig Daten zur Raumnutzung aus einem bisher kaum bekannten Lebensraum zu erfassen. Der ökologische Erkenntnisgewinn soll Empfehlungen für lebensraumverbessernde Maßnahmen in landwirtschaftlich geprägten Kulturlandschaften erbringen, die auch den Individuenaustausch zwischen Populationen der Art fördern. Die Ergebnisse der Telemetriestudie in der Goldenen Aue belegen eine regelmäßige Nutzung der reichstrukturierten Agrarlandschaft durch etablierte Individuen. Darüber hinaus wurde ein erfolgreiches Reproduktionsereignis dokumentiert. Das Geschlechterverhältnis und die Altersstruktur der erfassten Tiere (n = 11) waren ausgeglichen. Die Aktionsraumgrößen der Kater stimmten weitgehend mit dem in bewaldeten Lebensräumen ermittelten Raumanspruch männlicher Wildkatzen überein. Weibliche Wildkatzen nutzten in der reichstrukturierten Agrarlandschaft deutlich (um ca. 60 %) kleinere Streifgebiete als ihre Artgenossinnen in den bewaldeten Lebensräumen. Die Studie bestätigt die strenge Bindung der Wildkatze an deckungsbietende Strukturen. Die Analyse zur Habitatnutzung ergaben geschlechterspezifische Unterschiede: Während weibliche Wildkatzen in dem agrarisch dominierten Landschaftsausschnitt eher eine Bindung an flächige Strukturelemente, wie Feldgehölze- und kleine Waldinseln sowie aus der Nutzung genommene Streuobstwiesen zeigten, nutzten Kater hier lineare Elemente, wie strukturreiche Uferstreifen von Still-, und Fließgewässern sowie Weg- und Ackersäume intensiver. Die Daten belegen, dass der bisher unbeachtete Lebensraum – die reichstrukturierte Agrarlandschaft - durchaus alle wichtigen Lebensraumfunktionen für die Europäische Wildkatze erfüllen kann. Ein Grund für die geringe Größe der weiblichen Streifgebiete ist eine streng auf qualitativ hochwertige Habitatstrukturen begrenzte Lebensraumnutzung. Dabei scheint neben der Nahrungsverfügbarkeit ein ausreichend hohes Angebot deckungsbietender Strukturen in der Strauch- bis Baumklasse ausschlaggebend für eine Etablierung von Weibchen zu sein. In landwirtschaftlich geprägten Kulturlandschaften ist bei einer Mindestausstattung an deckungsbietenden Habitaten mit dem Vorkommen etablierter und reproduzierender Wildkatzen zu rechnen, insbesondere in der Peripherie besiedelter Waldlebensräume. Eine Prüfung der artenschutzrechtlichen Verträglichkeit im Rahmen der planungsrechtlichen Eingriffsregelung sollte zukünftig auch auf die angrenzenden Offenlandschaften (bis zu 4km) von bewaldeten Lebensräumen ausgeweitet werden. Als lebensraumverbessernde Maßnahme wird grundsätzlich eine Erhöhung der Strukturvielfalt in der Agrarlandschaft durch Schaffung oder/und Erhaltung von kleinräumigen Strukturen wie Feldgehölzen, Hecken und breiten Feld-Gewässerrainen mit aufkommender Sukzession empfohlen. Darüber hinaus gewährt dies einen Individuenaustausch zwischen räumlich getrennt voneinander liegenden (Teil)Populationen. / Since the end of the twentieth century, the solitary and strictly protected European wildcat (Felis silvestris) has spread from wooded habitats across the largely open agricultural landscape. Knowledge about habitat requirements in these landscape sections is not yet available for the species. The aim of the study is, for the first time, to generate space use data from so far less known habitat. The ecological gain of knowledge should provide recommendations for habitat-improving measures in agriculturally influenced cultural landscapes, which also promote the exchange of individuals between populations of the species. The results from the Golden Aue prove a regular use of a richly structured agricultural landscape by established individuals. In addition, a successful reproduction event was documented. The sex ratio and the age structure of the recorded animals (n = 11) were balanced. The home range sizes of males were largely consistent with the space requirement determined in wooded habitats. In a richly structured agricultural landscape, female animals clearly used (about 60 %) smaller home ranges than their conspecifics in the wooded habitats. The study confirms the strict binding of the wildcat to cover-providing structures. Gender differences were found: While females were more likely to be bound to areal structural elements such as copses, orchards and small forest islands, males used linear elements more extensively than females, such as structurally rich riparian strips of waterbodies and field margins in the agricultural landscape. The data show that the so far neglected habitat - the richly-structured agricultural landscape - can fulfill all important habitat functions for the European wildcat. One reason for the small female home ranges is probably an exclusive use of high-quality habitats, which in addition to the food availability also provide sufficient hiding places. In agricultural landscapes, assuming at least a minimum of cover habitats, the presence of established and reproducing wildcats can be expected, at least in the periphery of forest habitats. Increasing structural diversity in the agricultural landscape through the creation or / and preservation of small-scale structures such as copses, hedgerows and broad field-watercourses with emerging succession is recommended as habitat-improving measures. In addition, it provides for an exchange of individuals between spatially separated (sub) populations. In the future, an examination of the species protection compatibility in the context of the planning intervention regulations should also be extended to the adjacent open landscapes (up to 4 km) of forested habitats.
38

Adaptive Foraging in a Generalist Predator: Implications of Habitat Structure, Density, Prey Availability and Nutrients

Schmidt, Jason M. 09 August 2011 (has links)
No description available.
39

Human Impact on Space Use, Activity Patterns, and Prey Abundance of Madagascar's Largest Natural Predator, Cryptoprocta ferox

Wyza, Eileen M. 20 September 2017 (has links)
No description available.
40

Área de vida do lagarto saxícola Tropidurus semitaeniatus (Squamata: Tropiduridae) em área de Caatinga, Nordeste do Brasil / Home range of the saxicolous lizard Tropidurus semitaeniatus (Squamata: Tropiduridae) in Caatinga area, Northeastern Brazil

Daniel Cunha Passos 03 May 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A área de vida pode ser definida como o espaço físico necessário para um animal desempenhar as atividades essenciais para sua sobrevivência, desenvolvimento e reprodução. O conhecimento sobre área de vida é essencial para a compreensão dos processos que regem o uso do espaço e a organização social em populações animais. Neste estudo, investigamos aspectos das áreas de vida do lagarto saxícola, endêmico da Caatinga, Tropidurus semitaeniatus, avaliando possíveis variações intersexuais, ontogenéticas e sazonais nos tamanhos das áreas de vida, bem como elementos da organização social da espécie. A área de estudo consistiu em uma área típica de Caatinga stricto sensu, localizada no município de Pentecoste - Ceará. Realizamos coletas em dois afloramentos rochosos, nos quais demarcamos pontos de referência a cada cinco metros. Coletamos os lagartos residentes nestes afloramentos, registrando, para cada indivíduo, o sexo e o tamanho rostro-cloacal (mm), e posteriormente, identificando-o com marcação única. Vistoriamos cada afloramento durante 20 dias em cada estação (chuvosa e seca), respectivamente em junho e dezembro de 2011, realizando recapturas visuais e coletando registros de posições espaciais de cada indivíduo. Estimamos as áreas de vida pelo método do Polígono Convexo Mínimo, para os indivíduos recapturados pelo menos seis vezes. Obtivemos 56 áreas de vida, das quais 10 foram de machos, 20 de fêmeas e 26 de jovens. Não existiu relação entre os tamanhos das áreas de vida e os comprimentos rostro-cloacais dos indivíduos. Não houve diferenças sexuais, ontogenéticas ou sazonais nos tamanhos das áreas de vida. Contudo, o espaçamento entre as áreas de vida foi menor durante a estação chuvosa e a maioria das sobreposições entre áreas de vida também ocorreu neste período. Ao todo, registramos 81 sobreposições de áreas de vida, sendo estas mais frequentes entre fêmeas e jovens e menos frequentes entre pares de machos. A proporção da área de vida total sobreposta com outro indivíduo foi maior entre pares de fêmeas e menor entre pares de machos. Os machos estiveram associados em média com 1,5 fêmeas, possuindo de zero a sete áreas de vida de fêmeas sobrepostas com suas áreas de vida. O número de áreas de vida de fêmeas sobrepostas às áreas de vida de machos esteve positivamente associado ao tamanho dos machos. Por outro lado, não houve associação entre o número de áreas de vida de fêmeas sobrepostas às áreas de vida de machos e os tamanhos das áreas de vida dos machos correspondentes. Em suma, à luz do conhecimento acumulado sobre a história natural do organismo de estudo, acreditamos que sua extrema especificidade por ambientes rochosos e a disponibilidade limitada de habitats adequados à ocupação constituem fatores preponderantes na determinação dos padrões singulares de uso do espaço e organização social em T. semitaeniatus. / The home range may be defined as the physical space required for an animal to perform the essential activities for its survival, development and reproduction. The knowledge on home range is essential to understanding the processes that govern the use of space and the social organization in animal populations. Herein, we investigated home range aspects of the saxicolous lizard, endemic from Caatinga, Tropidurus semitaeniatus, evaluating possible intersexual, ontogenetic and seasonal variations in home range size, as well as elements of the social organization of the species. The study area was a typical Caatinga stricto sensu area, located in Pentecoste municipality - Ceará. We performed sampling at two rocky outcrops, where we defined reference marks each five meters. We collect the lizards living in these outcrops, recording for each individual, the sex and snout-vent length (mm), and subsequently, identifying it with unique marking code. We scanned each outcrop for 20 days in each season (rainy and dry), respectively on June and December 2011, performing visual recaptures and collecting records of spatial positions of each individual. We estimated the home range size by Minimum Polygon Convex method, for individuals recaptured at least six times. We obtained 56 home range areas, of which 10 males, 20 females and 26 juveniles. There was no relationship between home range size and snout-vent length of individuals. There were no sexual, ontogenetic or seasonal differences in home range size. However, the spacing between home range areas was lowest during the rainy season and the most of the home range overlaps also occurred in this period. Overall, we recorded 81 home range overlaps, which were more frequent between females and juveniles and less frequent among pairs of males. The proportion of the total home range overlapped with another individual was highest among pairs of females and lowest among pairs of males. Males were associated on average with 1.5 females, having from zero to seven females home range overlapped with their own home ranges. The number of female home ranges overlapped with male ones was positively associated with the body size of males. Moreover, there was no association between the number of female home ranges overlapped with male ones and the home range size of the corresponding males. In conclusion, in the light of accumulated knowledge about the natural history of the studied organism, we believe that their extreme specificity to the rocky environments and restricted availability of suitable habitats for its occupation are important factors in determining patterns of use of space and social organization in T. semitaeniatus

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