• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • Tagged with
  • 8
  • 8
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 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.
1

The ecology of short-toed eagle (Circaetus gallicus, GM.) in dadia-lefkimi-soufli forest complex, Thrace, Greece

Bakaloudis, Dimitris E. January 2000 (has links)
No description available.
2

On the ecology of lapwings Vanellus vanellus on aerodromes, with reference to the birdstrike hazard

Milsom, Timothy Philip January 1999 (has links)
No description available.
3

The basic ecology and the reproductive biology of feral American mink in the upper Thames

Yamaguchi, Nobuyuki January 2000 (has links)
No description available.
4

An ecosystem-based management approach for maintaining sandhill crane nesting habitat on northern Vancouver Island

Innes, Tyler 15 June 2010 (has links)
Sandhill Crane (Grus canadensis) migratory populations use wetland ecosystems on northern Vancouver Island for their breeding habitat. With wind energy development being proposed for the area, an ecosystem-based management approach is being used to maintain Sandhill Crane breeding habitat and biological diversity within the bog wetland complex of the Nahwitti Plateau at the northern tip of the island. Shelter, forage and nesting habitat suitability were identified and rated with a six-class scheme from April to October over a two-year period. Vegetation surveys and crane inventories were carried out in 2006 and 2007 to spatially map the structure and patterns of bog ecosystems used by migrating cranes. The highest-rated Sandhill Crane nesting habitat consisted of sedge and low shrub dominated blanket bog wetlands with vegetated mounds. Riparian features and bog forests were also determined to be important habitats for forage, shelter, and living habitat. Based on the analysis, three Wildlife Habitat Areas were proposed to maintain Sandhill Crane nesting habitat and connected ecological services that support ecosystem-based management objectives, including promoting human well-being.
5

A Study of Habitat Selection and Fluctuating Asymmetry of <em>Amybstoma tigrinum</em> at Henderson Island Wildlife Management Area in Jefferson County TN.

Ogle, Christopher Scott 01 May 2011 (has links)
Studies were conducted on a population of tiger salamanders, Ambystoma tigrinum, at Henderson Island Wildlife Management Area in Jefferson County, TN. Tests were conducted to locate the nonbreeding habitat of the salamanders and to detect any difference in fluctuating asymmetry (FA) between larval populations in a large, permanent pond and an ephemeral wetland. Drift fences were installed with pitfall traps at selected locations around each pond to determine nonbreeding habitat use by adults. Most adult salamanders were found using a blackberry (Rubus sp.) dominated old-field, a grassy field, and a shrub-grass mix field, which were all adjacent to the ponds. No statistical difference in FA between the 2 ponds.
6

Characteristics of managed and unmanaged water bodies influencing their suitability as mosquito breeding habitats in Bahir Dar, Ethiopia / Lämpligheten hos reglerade och oreglerade ytvattensamlingar som mygglarvshabitat baserat på deras egenskaper, i Bahir Dar, Etiopien

Carlström, Karolina, Renstål, Elin January 2014 (has links)
Mosquito-borne diseases like malaria, dengue fever, yellow fever and West Nile virus are serious problems in many parts of the world, especially in Africa, and partially in Ethiopia. Millions of people become infected and several hundred thousand people die worldwide from these diseases every year. The most conventional methods for mosquito vector control target female adult mosquitoes in a reactive way using insecticides. However, it is possible to perform proactive vector control through source reduction. The main focus of this study was to investigate if there are any associations between characteristics of managed still water bodies and the presence of mosquito larvae in Bahir Dar, Ethiopia. This was done by measuring twelve variables, both abiotic and biotic; pH, conductivity, dissolved oxygen, turbidity, biochemical oxygen demand, nitrate, phosphate, sulphate, carbonate, depth and presence of algae as well as collecting and counting mosquito larvae in ten different sites, during a time series of five weeks. The most common managed waters believed to serve as efficient breeding habitat for mosquitoes were ponds and ditches used for irrigation, drainage or cultivation. A total of 204 mosquito larvae were collected, where 95% were found in four of the ten sites, three of them were managed waters and the last one was unmanaged. Statistical analyses were performed in order to examine potential correlations and differences among the sites. Wilcoxon test was performed to investigate differences between managed and unmanaged waters. Simple linear regression analyses were performed to identify driving variables for the presence of mosquito larvae. The main results from the group tests were significant differences in mosquito larvae density between managed and unmanaged sites. Significant differences between mosquito sites and zero-sites for dissolved oxygen and sulphate were found. Simple linear regression revealed pH and dissolved oxygen as driving variables for mosquito larvae presence. It was concluded that resources should be put on treatment or manipulation of ponds, which were considered the preferred mosquito breeding habitats. However, if conflicts arise among interests concerning food production, measures must be planned and performed thoughtfully or focus should be put on less controversial breeding habitats. Among the driving variables, dissolved oxygen was the suggested variable to manipulate in order to reduce mosquito larvae populations. / Myggburna sjukdomar som malaria, denguefeber, gula febern och West Nile viruset orsakar allvarliga problem i många delar av världen, särskilt i Afrika, och till viss del Etiopien. Miljontals människor världen över blir smittade och flera hundratusen dör varje år till följd av dessa sjukdomar. De konventionella metoderna för att kontrollera och minska spridningen av myggburna sjukdomar handlar om att kontrollera vuxna myggor med insektsmedel. Det är dock möjligt att utföra en mer förebyggande vektorkontroll genom att minska populationen. Fokus för denna studie var att undersöka om det fanns några samband mellan mygglarvsförekomst och egenskaperna hos mänskligt reglerade eller oreglerade vatten i och kring Bahir Dar i Etiopien. Detta gjordes genom att mäta tolv variabler, både abiotiska och biotiska såsom; pH, konduktivitet, löst syre, turbiditet, biokemisk syreförbrukning, nitrat, fosfat, sulfat, karbonat, djup och algförekomst, samtidigt som mygglarver samlades in och räknades, vilket utfördes på tio olika platser under fem veckor. Den vanligaste typen av reglerade vatten som potentiellt skulle kunna utgöra effektiva mygglarvshabitat ansågs vara dammar och diken som används för bevattning, dränering eller odling. Totalt samlades 204 mygglarver in och 95 % av dem fanns i enbart fyra av de tio etablerade mätplatserna, där tre var reglerade och den sista var oreglerad. Statistiska analyser utfördes för att undersöka potentiella samband och skillnader i mygglarvsförekomst och uppmätta variabler bland de tio mätplatserna. Wilcoxons metod användes för att undersöka om det fanns skillnader mellan reglerade och oreglerade ytvattensamlingars larvförekomst och egenskaper. Enkel linjär regressionsanalys utfördes för att hitta eventuella drivvariabler som därmed anses styra mygglarvsförekomsten. De huvudsakliga resultaten i studien var att det förekom en signifikant skillnad i mygglarvsdensitet mellan reglerade och oreglerade ytvattensamlingar. Signifikanta skillnader i löst syre och sulfat förekom även mellan myggsiter och nollsiter. Enkel linjär regression visade på att pH och löst syre var de mest drivande variablerna för mygglarvsförekomsten i denna studie. Slutsatsen var att dammar utgjorde de mest tilltalande habitaten i samband med mygghonors äggläggning och därför borde prioriteras med avseende på resursfördelning vid planering och utförande av vektorkontroll. Om det skulle uppstå konflikter mellan olika intressen som kan äventyra matproduktionen bör insatser planeras och genomföras med försiktighet eller istället göras i andra mindre kontroversiella mygglarvshabitat. Den drivvariabel som ansågs vara den mest lämpliga att manipulera var löst syre.
7

Applying Ecological Theory to Amphibian Populations to Determine if Wood Frogs (Lithobates sylvaticus) are Ideal and Free when Selecting Breeding Habitat

Braunagel, Taylor M 02 April 2021 (has links)
Amphibian populations are declining globally due to a litany of factors including pollution, disease, climate change, and most importantly, habitat destruction. As most amphibian life histories involve their populations being recruitment limited, focusing on the mechanism behind breeding habitat selection will reveal useful cues that managers may use to increase abundance and breeding success. Though there are many theoretical models that describe the distribution of animals in response to a resource, the ideal free distribution (IFD) theory has not yet been applied to amphibian settling decisions. Through this application of the IFD, I have found that a population of wood frogs (Lithobates sylvaticus) in Patuxent National Wildlife Refuge select vernal pools that are large, deep, and hold water into the summer months to breed from 2010-2015. This information will provide managers with the ability to predict sites where wood frogs will breed in the future, as well as describe the cues that wood frogs are cueing in on so we can protect, alter, or create ideal breeding habitat.
8

Landscape-level heterogeneity of agri-environment measures improves habitat suitability for farmland birds

Roilo, Stephanie, Engler, Jan O., Václavík, Tomáš, Cord, Anna F. 21 May 2024 (has links)
Agri-environment schemes (AESs), ecological focus areas (EFAs), and organic farming are the main tools of the common agricultural policy (CAP) to counteract the dramatic decline of farmland biodiversity in Europe. However, their effectiveness is repeatedly doubted because it seems to vary when measured at the field-versus-landscape level and to depend on the regional environmental and land-use context. Understanding the heterogeneity of their effectiveness is thus crucial to developing management recommendations that maximize their efficacy. Using ensemble species distribution models and spatially explicit field-level information on crops grown, farming practice (organic/conventional), and applied AES/EFA from the Integrated Administration and Control System, we investigated the contributions of five groups of measures (buffer areas, cover crops, extensive grassland management, fallow land, and organic farming) to habitat suitability for 15 farmland bird species in the Mulde River Basin, Germany. We used a multiscale approach to identify the scale of effect of the selected measures. Using simulated land-use scenarios, we further examined how breeding habitat suitability would change if the measures were completely removed and if their adoption by farmers increased to meet conservation-informed targets. Buffer areas, fallow land, and extensive grassland were beneficial measures for most species, but cover crops and organic farming had contrasting effects across species. While different measures acted at different spatial scales, our results highlight the importance of land-use management at the landscape level—at which most measures had the strongest effect. We found that the current level of adoption of the measures delivers only modest gains in breeding habitat suitability. However, habitat suitability improved for the majority of species when the implementation of the measures was increased, suggesting that they could be effective conservation tools if higher adoption levels were reached. The heterogeneity of responses across species and spatial scales indicated that a mix of different measures, applied widely across the agricultural landscape, would likely maximize the benefits for biodiversity. This can only be achieved if the measures in the future CAP will be cooperatively designed in a regionally targeted way to improve their attractiveness for farmers and widen their uptake.

Page generated in 0.0872 seconds