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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.
11

Dusky dolphin (Lagenorhynchus obscurus) occurrence and movement patterns near Kaikoura, New Zealand

Dahood, Adrian D. 16 January 2010 (has links)
In Kaikoura, New Zealand dusky dolphins (Lagenorhynchus obscurus) are economically and ecologically important. However, more information on key habitat requirements is needed to develop an effective management plan for them. I use systematic shore-based observations and tour operator gathered boat-based observations and review night-time foraging observations to explore dusky dolphin occurrence and movement patterns. I discuss possible influence of prey on these patterns. From January to December 2006, I conducted crepuscular observations from three clifftop stations. With these geospatial data I examined occurrence, mean speed, and linearity over seasonal, diel, and tidal temporal scales. From October 1995 to November 2006 tour guides recorded GPS locations for over 5,000 dusky dolphin groups, allowing me to examine seasonal occurrence patterns. For both datasets I quantified occurrence patterns relative to depth, distance from the Kaikoura Canyon, and distance from shore. I reviewed the three studies conducted on dusky night foraging behavior in Kaikoura. I explore the effects of seasonal and lunar-scale changes in night-time light levels on dusky dolphin foraging behavior. Duskies exhibited seasonal and diel, but not tidal occurrence and movement patterns. Dolphins were found farther offshore, in deeper water, and travelling faster in winter and approaching sunset. The areas of highest sightings density were associated with the Kaikoura Canyon, and shifted almost entirely into the canyon in winter and approaching sunset. Dolphins made sharper turns during summer. Dolphins were, on average, closer to the Kaikoura Canyon than to shore. Seasonal occurrence patterns described by tour operator data agreed with those described by geospatial data collected by shorebased observers. Duskies exhibited flexible foraging behavior and appeared to use both seasonal and lunar phase specific tactics. Night-time light levels appeared to influence dusky foraging behavior, possibly through changes in prey behavior. Prey availability and behavior patterns appeared to influence dusky occurrence and movement patterns. The dolphins' affinity for the Kaikoura Canyon may reflect a strategy to maximize access to prey.
12

Temporal variation and inter-relationship of movement and resource selection of red deer (Cervus elaphus) with respect to climate: a case study

Hu, Qinglin January 2006 (has links)
Red deer (Cervus elaphus) is one of at least 31 herbivorous exotic mammals existing in New Zealand. All of these species have the potential to affect environmentral and production values. Reducing their impacts on their values, strengthening effective managements are important issues to a variety of agencies within New Zealand including the Department of Conservation (DOC), Ministry of Agriculture and Forestry (MAF), local and regional governments. This research studied animal movement pattern and habitat use of 2 GPScollared red deer in the Canterbury high country and found (1) deer movement was affected by climatic variables such as rainfall and temperature, which had positive or negative effect on it, and had seasonal variation; (2) deer had dominant landcover use categories, depending on climate, season, and individual characteristics (3) deer had different movement patterns in terms of hourly distances. The purpose of the study is to draw accurate inferences from spatially explicit data for biosecurity managers and policy-makers through: (1) using global positioning system (GPS) as a tool to elucidate the application of GPS on red deer in wildlife management; (2) Animal Movement Analysis Arc View® 3.2 Extension under Arc View® Geographic Information System (GIS); (3) Animal movement analysis which used Generalized Additive Models (GAMs) to show how the movement of red deer was affected by different periods of time, seasons months and climatic variables (for example, rainfall and temperature).
13

Habitat Use of Shovelnose Sturgeon Scaphirhynchus Platorynchus in the Lower Mississippi River

Kroboth, Patrick Thomas 13 December 2014 (has links)
The habitat requirements of shovelnose sturgeon populations are unknown for the lower Mississippi River. Active acoustic telemetry was used to measure temporal variation in habitat use of shovelnose sturgeon and preference for depth, surface current velocity, and riverbed rugosity and slope by the population and within sandbar microhabitats. Shovelnose sturgeon occupied habitats differently throughout the year; and, within habitats, areas of moderate depth and surface current velocity and smooth riverbed were preferred. Within sandbars, environmental conditions did not differ from the surrounding environment, yet frequent aggregations of individuals in the lower portion of sandbars often in close proximity suggest habitat preference at a scale greater than the 5 ha measured. Results of this study provide information on seasonal habitat use patterns and methods that can be applied to a long-term dataset to identify the habitat requirements of shovelnose sturgeon.
14

Feral hogs in central Mississippi:home range, habitat use, and survival

Hayes, Robert Clay 05 May 2007 (has links)
I examined home range, habitat use, and survival of 29 feral hogs in central Mississippi using radio telemetry. During the dry season (1 April - 31 October 2005), densely-vegetated habitats were very important in home range placement (2nd-order selection) with selection favoring seasonallylooded old fields, followed by old fields and managed openings. During the wet season (1 November 2005 - 31 March 2006), old fields were still preferred followed by agricultural fields, but flooded old fields were not preferred. For habitat selection within the home range (3rd-order selection), hogs preferred old fields and managed openings during the dry season. All habitats were used randomly within home ranges during the wet season. Dry and wet season survival rates were 80.8% and 41.4%, respectively. Hunting was the major cause of mortality (80 ? 100%). Seasonal differences in habitat selection may have been caused by flooding of preferred habitats, food availability and hunting.
15

Ecological determinants of muntjac deer Muntiacus reevesi behaviour

Keeling, Jonathan Giles Matthew January 1995 (has links)
No description available.
16

Conservation biology of the babirusa, Babyrousa babyrussa, in Sulawesi, Indonesia

Clayton, Lynn Marion January 1996 (has links)
No description available.
17

SWAMP RABBIT RESPONSES TO HABITAT CONDITIONS IN BOTTOMLAND HARDWOOD FORESTS IN SOUTHERN ILLINOIS

Hillard, Elizabeth M 01 May 2019 (has links)
Reforestation of bottomland hardwood (BLH) forests has occurred within the Lower Mississippi Alluvial Valley (LMAV), USA, to support a wide range of ecosystem services, but especially wildlife habitat enhancement. As ecosystem restoration efforts proceed in BLH ecosystems, managers and policymakers are seeking criteria to evaluate wildlife habitat enhancement goals. Specialist wildlife that evolved within forest ecosystems can be sensitive to the composition, structure, and function of an ecosystem in relation to the system's natural or historical range of variation and thereby serve as indicators of habitat quality. The swamp rabbit (Sylvilagus aquaticus) is a specialist of BLH forests throughout the LMAV and therefore may be an appropriate indicator species for this ecosystem. In Chapter 1, I reviewed peer-reviewed literature to evaluate the utility of swamp rabbits as an indicator species according to three commonly-used criteria: habitat factors defining swamp rabbit relationships to BLH forests, the importance of swamp rabbit habitat to other wildlife, and the efficiency of swamp rabbit monitoring. I concluded that the swamp rabbit is a suitable indicator of wildlife habitat quality in BLH ecosystems in the LMAV because they evolved and remain endemic to the ecosystem, use habitat that integrates desirable characteristics that positively influence wildlife biodiversity, and are easy to monitor routinely.
18

Foraging biology and habitat use of the southern African ice rat, Otomys sloggetti robertsi

Schwaibold, Ute Heidrun 15 November 2006 (has links)
Student Number : 9613963J - PhD thesis - School of Animal, Plant and Environmental Sciences - Faculty of Science / Animals living in cold environments show physiological, morphological and behavioural adaptations to low temperatures. The African ice rat, Otomys sloggetti robertsi, which is endemic to the southern African Drakensberg and Maluti mountains above 2000m, is an interesting exception since, unlike most alpine small mammals, it does not hibernate or display torpor and is physiologically poorly adapted to low temperatures. It is a strict herbivore, feeding on a low quality diet. Ice rats do show some morphological (e.g. short tails) and behavioural (e.g. communal huddling; constructing underground burrows) adaptations, but little else is known about their biology, particularly how they maximise energy gain to meet thermoregulatory requirements, especially during cold periods. Since feeding represents the primary method of energy gain in endotherms, I studied aspects of the foraging biology of ice rats, including gut structure, foraging patterns and habitat choice. The gut structure of O. s. robertsi is well adapted for a high fibre, herbivorous diet and shows broad similarities with those of its mesic- and arid-occurring relatives. However, O. s. robertsi showed increased dimensions of several foregut organs which may be adaptations for increased energy uptake and/or poor diet quality in alpine environments. Furthermore, females had a larger stomach as well as a longer caecum, small and large intestine in summer than in winter but the gut of males was unaffected; such sexual asymmetry may be related to increased energy requirements of females during pregnancy and lactation. Environmental influences on the aboveground behaviour of O. s. robertsi were investigated by recording the duration of behaviours as well as sequential transitions among behaviours. Ice rats spent most of their day foraging and basking, and much time was spent in their underground burrows. Seasonal comparisons revealed that ice rats spent significantly more time acquiring energy through foraging in winter, whereas they remained below ground for longer periods of time during the middle of the day in summer to escape extreme heat and solar radiation. To understand how low temperatures and predation influenced foraging patterns, the behaviour of ice rats was studied in summer and winter in a population where predators were minimal and in another population which experienced higher levels of predation. Ice rats are central place foragers that travel short distances to forage and display significant seasonal variation in their foraging patterns. In the absence of predation risk, ice rats generally returned to a central place with forage, even though returning to a burrow after foraging in winter was energetically costly. However, these costs must be weighed against the benefits of avoiding exposure to low temperatures by feeding under cover as well as the loss of collected food and possible injury associated with aggressive interactions with conspecifics. Under moderate predation pressure in both seasons, ice rats followed a central place foraging strategy to minimise predation risk, always returning to a burrow entrance with forage collected elsewhere. However, when no perceivable threat was observed, ice rats displayed ‘optimal’ foraging patterns in summer similar to those recorded in the absence of predation pressure and only returned to a burrow with forage as distance from that burrow increased, suggesting that ice rats display facultative foraging decision making in response to multiple environmental cues. The distribution of occupied ice rat burrows was correlated against several environmental factors to determine microhabitat requirements. Ice rat burrows were situated in close proximity to herbaceous and wetland plants, but away from woody vegetation, suggesting that habitat choice is related to the presence of food plants and reduction of shade, facilitating short travel distances during foraging as well as promoting basking. Despite the physiological shortcomings of ice rats, the gut structure, foraging behaviour, and habitat choice of the taxon are adapted for life in cold alpine habitats, most likely by maximising energy intake. Similarities in foraging behaviour and habitat use between O. s. robertsi with its closely-related arid-occurring relative Parotomys spp. suggest phylogenetic influences, but it is possibly more a reflection of similar phenotypic responses to the extreme habitats inhabited by these otomyines.
19

\"Mamíferos de médio e grande porte num remanescente de Cerrado no sudeste do Brasil (Itirapina, SP)\" / Medium and large sized mammals in a Cerrado remnant in South-eastern Brazil (Itirapina, São Paulo)

Hulle, Norberto Lopes 19 April 2006 (has links)
Um dos primeiros passos para a conservação e uso racional de um ecossistema é o inventário da sua fauna. A região Neotropical abriga 24% das espécies de mamíferos do planeta, ou seja, cerca de 1.340 espécies, das quais 199 ocorrem no Cerrado. Os objetivos deste estudo foram conhecer a fauna de mamíferos de médio e grande porte da Estação Ecológica de Itirapina (EEI), um remanescente de cerrados abertos na região central do estado de São Paulo, e verificar se há um padrão de ocupação de habitats por parte dessas espécies. Foram obtidos 75 registros com a contagem visual e 77 com as armadilhas fotográficas detectando nove espécies pelo método de contagem visual e dez pelo método de armadilhas fotográficas, totalizando 13 espécies. Três espécies foram avistadas por terceiros, totalizando, com estudos anteriores, 22 espécies para a EEI. Em nenhum dos métodos foi atingida a assíntota nas curvas de rarefação de espécies, o que sugere que cada método deve resultar em um maior número de espécies com maior tempo de amostragem. A taxocenose de mamíferos da EEI foi comparada a outras taxocenoses de Cerrado do Brasil, sendo que a área das localidades parece determinar em grande parte (63%) a riqueza de espécies de mamíferos de médio e grande porte. Uma análise de agrupamento utilizando a composição destas resultou em dois grupos distintos: um contendo as localidades de área relativamente menor e do sudeste e outro contendo as demais localidades, com áreas iguais ou maiores a 10.500 ha. A EEI mostrou maior similaridade com a gleba Pé do Gigante do Parque Estadual de Vassununga, SP, cujas riquezas foram as menores. Quanto ao uso do ambiente na EEI, os resultados obtidos pelos dois métodos de amostragem seguiram o mesmo padrão geral, onde tanto o número de espécies quanto o de registros foi maior na fisionomia mais aberta e decresce nas fisionomias mais fechadas. O teste de χ² para o número de registros em cada fisionomia foi significativo para os dois métodos, indicando que os mamíferos não estão distribuídos de acordo com a disponibilidade das fisionomias. Os resultados dos testes foram significativos apenas para Euphractus sexcintus e Lepus europaeus, mas em apenas um dos métodos de amostragem. O campo limpo foi a fisionomia que resultou nos maiores valores de χ² parcial em todos os testes, e aparentemente tem grande importância para a taxocenose de mamíferos de médio e grande porte da EEI. / A crucial step for the conservation of any ecosystem is a complete faunal survey of the area. The Neotropics harbor 24% of the world’s the mammalian species, approximately 1.340 species, 199 of wich occur in the Cerrado. The objectives of this study were to sample the mammals of medium and large size at the Estação Ecológica de Itirapina (EEI), a Cerrado remnant in the center of the State of São Paulo, south-eastern Brazil, and to verify patterns of habitat use in these species. Two different sampling methods were used, visual censuses and camera-trapping. Seventy five records were obtained using visual censuses and detecting nine species and seventy seven by camera-trapping, detecting 10 species, totalling 13 species. Aditional three species were sighted by other researchers, raising the number to 22 species for EEI, with other two studies. None of the methods resulted in asymptotic rarefaction curves, which suggests that both methods will detect mores species with a longer sampling time. The species richness and composition of the EEI mammal assemblage was compared to other five Cerrado assemblages and the area of surveyed localities seems to determine, in great part (63%) the mammal species richness. The cluster analysis resulted in 2 main groups, one containing the localities with relatively small areas from the southeast Brazil, and the second group with the remaining localities, with areas equal or greater than 10,500 ha. EEI was most similar to the Pé do Gigante Cerrado Fragment in Parque Estadual de Vassununga, São Paulo, and both fragments exhibited smallest species richness. What regards to habitat use results of both methods suggest the same general pattern, where both the number of records and the number of species are greater in open physiognomies and decrease in more closed habitats. A χ² test for the number of records in each physiognomy was significant for both methods, confirming that Cerrado mammals are not distributed according to the availability of the physiognomies. Taking into account each species individually, only Euphractus sexcinctus and Lepus europaeus showed significant deviation from expected, and only for one of the sampling methods (visual census for E. sexcinctus and camera trapping for L. europaeus). In all tests the campo limpo physiognomy showed the highest partial χ² values, and seems to have great importance to the medium and large size mammal assemblage of the EEI.
20

Alterações no uso de hábitat por aves de subosque em paisagens fragmentadas / Change in habitat use by understory birds in fragmented landscapes

Santos, Júlia Ferrúa dos 29 July 2016 (has links)
Os efeitos da perda de hábitat e da fragmentação já estão bem estabelecidos na literatura, porém pouco se sabe sobre como o uso do habitat pode ser modificado em função de alterações na quantidade e na qualidade da mata. Este trabalho tem como objetivo compreender melhor como a perda e modificação do hábitat afeta o uso do espaço pelas aves de subosque na escala da comunidade e população. Para isso, utilizamos um banco de dados de aves, que inclui informação sobre captura e recaptura de 2.121 indivíduos, coletados em um gradiente de cobertura florestal, com fragmentos de 2,85 ha a 10.000 ha, localizados em Mata Atlântica no estado de São Paulo. As análises foram feitas por espécie, por grupos de espécies de acordo com guilda trófica e grau de sensibilidade a alterações antrópicas, e para a comunidade de forma geral. Para testar se a qualidade da vegetação influencia a abundância e frequência de uso do espaço, utilizamos dados de três áreas de florestas contínuas, com diferentes níveis de alteração (floresta secundária, mata com corte seletivo e mata madura). Observamos que, apesar de haver uma queda na abundância total da comunidade em fragmentos pequenos, há um aumento na frequência de uso do ambiente, evidenciado pelo aumento na taxa de recaptura com a perda de habitat. O mesmo padrão foi encontrado para aves com média sensibilidade, frugívoras e insetívoras. Aves com baixa sensibilidade, no entanto, mostraram maiores abundancia e taxa de recaptura em fragmentos menores e áreas mais desmatadas. Verificamos também que a frequência de uso do espaço foi maior em floresta secundária, bem como a abundância de aves. Nossos resultados sugerem que além de conduzir a uma perda de espécies e de indivíduos, a perda de hábitat também leva ao aumento na intensidade do uso do habitat. Este aumento se dá em particular para espécies de média sensibilidade, uma vez que espécies com alta sensibilidade estão ausentes de fragmentos pequenos. Observamos que, além da matriz como barreira à dispersão, a própria qualidade da mata se apresenta como um fator que modifica o uso do habitat. Esta variação no uso do habitat pode impedir que as mesmas desenvolvam seu papel de dispersores de sementes entre os fragmentos. Por fim, estudos sobre uso do espaço hoje praticamente não abordam a intensidade com que o hábitat é utilizado pelos indivíduos, sendo uma informação importante que pode ser facilmente estudada através de dados de captura e recaptura, geralmente subutilizados / The effects of habitat loss and fragmentation area well established in the literature, however not much is known about how habitat use can be modified due to alterations in habitat quantity and quality. This work aims to understand how habitat loss and changes to habitat quality affects the habitat use by understory birds at the community and population level. We analysed a database, which includes capture and recapture data from 2.121 individuals, of birds sampled along a gradient of Atlantic Forest cover and fragment size varying from 2,85 ha to 10.000 ha in the São Paulo State. We analysed data by species, by groups of species according to their trophic guilds and sensitivity to habitat change, and at the community level. To test if the quality of vegetation affects species abundance and the intensity of habitat use, we used data from three continuous forests, with different levels of habitat modification (secondary forest, forest selective logged and mature forest). Our results show that, although the total species abundance decreased in small fragments, the intensity of habitat use increases, as shown by the increase in recapture rates with habitat loss. This pattern was observed for birds with high and medium sensitivity, frugivorous and insectivorous. Species with low sensitivity, however, showed higher species abundance and recapture rate in small fragments. We also show that the frequency of habitat use was higher in secondary forest, as was the abundance of individuals. Our results suggest that habitat loss not only leads to smaller populations, but it also modifies the intensity of habitat use. This pattern was mostly observed for species with medium levels of sensitivity, as highly sensitive species were no longer present in small patches. Our results indicate that the matrix may act as a barrier for dispersal, but habitat quality may also further influence habitat use. This variation in habitat use can affect birds ability to disperse seeds between the fragments. Finally, studies of habitat use almost never focuses on the intensity of habitat use, even though this information can be easily evaluated using capture and recapture data, with the latter being usually underused

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