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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

The Impact of Neonicotinoid Pesticides on Wild Bees in an Intensive Agriculture System

Gaudreault, Emma 28 September 2020 (has links)
Neonicotinoids are broad spectrum insecticides that are widely used to control many insect pests. In Ontario they are applied directly to the seeds of most corn and soy crops, after which they are incorporated into the tissues of the developing plant. While researchers have investigated how these insecticides impact honeybee health, much less attention has been given to the effects of neonicotinoids on wild pollinators. Ground nesting bees face exposure to neonicotinoids both in the soil, where they nest, as well as through other exposure routes (e.g, nectar and pollen of treated plants). I studied whether a higher concentration of neonicotinoid pesticides in soils within and near corn and soy crops is negatively associated with the abundance and diversity of ground nesting bees. To determine whether an association exists between soil neonicotinoid concentration and the abundance of associated ground nesting bee communities, I surveyed 16 eastern Ontario (mainly corn and soy) farms once per month from May to August, 2019, sampling the bee communities, soil pesticide levels, and floral resources. I found a significant interaction between the sampling period and neonicotinoid soil concentrations on ground nesting bee abundance. However, no similar relationship existed for an analysis with non ground nesting bees only. Specifically, I found that high concentrations of soil neonicotinoids were associated with lower expected bee abundances and low seasonal variation, a low concentration of soil neonicotinoids was associated with a high degree of seasonal variation, including spikes of relatively high expected abundances, and that sites with no neonicotinoids were associated with low seasonal variation and moderately high expected bee abundances. The number of floral units at a site was also positively associated with bee abundance, which is consistent with what has been reported in other studies. Diversity data are currently being processed off-site and unavailable at the time of publication. My results provide evidence that there exists the potential for higher risks of neonicotinoid seed treatments to ground nesting bees compared to the non-ground nesting community.
32

Trees, Birds, and People: Resource Use and Interspecific Interactions in a Namibian Cavity Nesting Guild

Millican, David Marshall 15 May 2023 (has links)
Cavity-nesting guilds are diverse communities of organisms that are hierarchically structured around the creation of and competition for tree holes as nest sites. Quantifying these communities as networks of interconnected species, or "nest webs", is a proven and efficient method for identifying important species and interactions within a cavity-nesting guild that can aid the management of these often threatened communities. Yet nest web data does not provide information regarding how natural resource managers are to encourage the support and adoption of conservation behaviors. This dissertation comprises two broad studies: one describing a cavity-nesting guild in central Namibia, and the other exploring methodology for identifying an effective flagship species for local conservation. In chapter 1, I provide background information of my study system and a review of the cavity-nesting and flagship species literature. In chapter 2, I quantify the species and resources within a cavity-nesting guild and create a cavity nest web to depict cavity creation and use in central Namibia. All cavity-nesters depended on sparse, large trees, which likely contributed to limited use of tree species across the guild. Cavity-excavators were of disparate importance for secondary cavity-nesters: important for small- and medium-bodied species but mostly unimportant for large-bodied species who depend more on large trunk hollows. In chapter 3, I describe and compare species-specific cavity resource niches among guild members to explore potential instances of cavity resource partitioning. Use of nest cavities appears to sort out by size among both cavity-excavators and secondary cavity-nesters. Excavators appear to partition cavity substrate spatially by decay class, while spatial partitioning among secondary nesters was largely by cavity type. Most interesting is the apparent temporal partitioning of large excavations among medium- and large-bodied cavity-nesters. In chapter 4, I explore a novel approach to flagship species selection that identified all previously-existing traits for flagship species, numerous traits specific to culture and personal experience, and a dozen new traits that were previously not recognized as potentially important for flagship species. This method shows considerable promise as a tool for investigating preferences for wildlife among broad stakeholders, as well as for engaging local people in wildlife conservation. / Doctor of Philosophy / Holes in trees, or cavities, are important resources for many birds, who use cavities as a safe place for raising young. Cavity-nesting birds are linked together in a cavity "nest web" based on the types of cavities used by each species. Understanding how birds are linked with each other and with certain types of cavities is critical in order to design conservation plans that preserve important community relationships. However, successful conservation also depends on strong support from local people, who are most often the people tasked with implementing the conservation actions. Flagship species can be used to gain support from necessary groups of people for specific conservation missions. This dissertation consists of two broad studies: the first study describes a community of cavity-nesting birds in Namibia, and the second explores a new way to investigate how people connect with wildlife through emotional connections. In chapter 1, I provide background information on my area of research. In chapter 2, I outline the different trees, cavities, and birds at the study site and estimate their abundance in the area. I also create a cavity nest web that illustrates the links between species. Large trees were relatively uncommon, but were important for all birds in the community. Cavities made by other birds, such as woodpeckers, were very important for small- and medium-sized species, but were mostly unimportant for large-sized species. In chapter 3, I compare the tree cavities used by different species, including the types of trees, cavities, and cavity sizes. I also explore multiple ways by which cavity-nesting birds might be dividing cavities between different species. Our most interesting finding was how medium-sized species seem to share cavities in time rather than in space; some species (i.e., small owls and woodpeckers) breed before some larger species that use the same type of cavity. Breeding early may be a way for some species to avoid competition with more competitive species, and may be the first example of this strategy being used by multiple cavity-nesters in a community. In chapter 4, I explore a new method for selecting flagship species. This method uncovered all traits that have been previously recommended for flagship species, as well as many traits specific to culture and personal experience. We also identified a dozen new traits that were previously not considered to be important for flagship species. Our new method is very promising as a tool for investigating preferences for wildlife among broad stakeholders, and for engaging and involving local people in wildlife conservation.
33

Nesting Ecology and Reproductive Correlates in the Desert-nesting Gray Gull Larus Modestus

Aguilar Pulido, Roberto E. (Roberto Eric) 05 1900 (has links)
General objectives of my study were to describe the reproductive ecology of gray gulls in the large Lealtad colony, with emphasis on demographic parameters and physiological adaptations of eggs and chicks, which would complete some original objectives established in the early 1980's by Guerra and Fitzpatrick. Specifically, my study focused on describing, then comparing with other desert and non-desert nesting larids, interactive effects of ambient physical conditions and nest-site predation on eggs and chicks.
34

The effects of grazing on songbird nesting success in Grasslands National Park of Canada

Lusk, Jennifer 24 August 2009 (has links)
I examined the effects of nest site vegetation structure and cattle grazing on songbird nesting success in native mixed-grass prairie in Grasslands National Park of Canada and Mankota Community Pastures in southwestern Saskatchewan. This is the first study to compare songbird nesting success in season-long grazed and ungrazed native mixed-grass prairie. Sprague’s pipit, Baird’s sparrow, vesper sparrow, lark bunting, and chestnut-collared longspur all selected for denser vegetation at the nest than was generally available. Sprague’s pipit daily nest survival declined with increased vegetation density and litter depth at the nest site. Vegetative cover did not influence daily nest survival of the other species. Environmental conditions during the study may have resulted in an increased risk of predation for Sprague’s pipits nesting in greater cover. Grazing did not influence daily nest survival of any of the 5 species. Low-moderate intensity cattle grazing appears compatible with management for prairie songbirds in native mixed-grass prairie.
35

The effects of grazing on songbird nesting success in Grasslands National Park of Canada

Lusk, Jennifer 24 August 2009 (has links)
I examined the effects of nest site vegetation structure and cattle grazing on songbird nesting success in native mixed-grass prairie in Grasslands National Park of Canada and Mankota Community Pastures in southwestern Saskatchewan. This is the first study to compare songbird nesting success in season-long grazed and ungrazed native mixed-grass prairie. Sprague’s pipit, Baird’s sparrow, vesper sparrow, lark bunting, and chestnut-collared longspur all selected for denser vegetation at the nest than was generally available. Sprague’s pipit daily nest survival declined with increased vegetation density and litter depth at the nest site. Vegetative cover did not influence daily nest survival of the other species. Environmental conditions during the study may have resulted in an increased risk of predation for Sprague’s pipits nesting in greater cover. Grazing did not influence daily nest survival of any of the 5 species. Low-moderate intensity cattle grazing appears compatible with management for prairie songbirds in native mixed-grass prairie.
36

Snag longevity, bird use of cavities, and conifer response across three silvicultural treatments in the Oregon Coast Range /

Walter, Scott T. January 2003 (has links)
Thesis (M.S.)--Oregon State University, 2004. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.
37

Hnízdní biologie plameňáka růžového (Phoenicopterus ruber) v zoo Ohrada / Nesting biology of the Pink Flamingo (Phoenicopterus ruber) in the zoo Ohrada

ŠENKÝŘOVÁ, Marie January 2013 (has links)
Flamingos belong to the Phoenicopteridae family. They are occurred from India, through southern Europe to South Africa, flamingo cover Caribbean and southern half of South America at the Western Hemisphere. They consist mainly monogamous couples and their nesting is highly synchronized. They lay usually one egg, even if there are the records about laying two eggs. Incubation of the Greater flamingo (Phoenicopterus ruber) takes 26-32 days. The thesis was performed in Zoo Ohrada Hluboká nad Vltavou, where observation of nesting behavior at Greater flamingos (Phoenicopterus ruber roseus) was the main focus of observation. It was used the method of the direct observation, add a notes of zoo-keeper. Birds were recognition by color rings with a three-letter code. The main aims were the observation nesting activities which were compared at different times, between males and females and between individuals. Evaluating the parameters of the breeding to improve breeding was other aim. There were determined, that nesting activities were different among individuals, among couples and also among sex of individuals. Display of nesting activities also depended on the situation, in which individuals found, if it had an empty nest, egg or chick, or if the egg were lost and had to lay new one. It was determined, that the nesting activities of individuals varies accord the season. They are too high synchronization in the period of laying eggs and hatching chicks. Observing individuals did more non-nesting activities.
38

False Crawls of Loggerhead Turtles (Caretta caretta): Causation and Impacts on Nesting Success in Broward County, Florida

Zielinski, Michele 21 March 2014 (has links)
The greatest sea turtle nesting in the United States occurs in Florida, which accounts for more than 85% (Shoop et al, 1985). Five species of sea turtle have been documented nesting in Florida, including the loggerhead (Caretta caretta), green (Chelonia mydas), leatherback (Dermochelys coriacea), kemp’s ridley (Lepidochelys kempi), and hawksbill (Eretmochelys imbricata) sea turtles. In southeast Florida, the loggerhead is the most common nester. The distribution of loggerhead nest numbers laid in 85 survey zones stretching along Broward County beaches between the Palm Beach County line and the Port Everglades Inlet have been highly correlated for aver a decade (P<<0.001). This study attempted to understand the reasons for this distribution by evaluating the distributions of false crawls and nesting success rates from 2000 through 2010. The nest and false crawl patterns in the 85 beach zones were all highly correlated for all 11 years (P < 0.01). These strong positive correlations indicate that these turtles receive preemergence cues, such as visual or depth profile, to primarily determine their emergence locations. However, weaker correlations between yearly nesting and nesting success patterns indicate that on-beach (post-emergence) cues also play a less important role in nest site selection.
39

EFFECTS OF MULTIPLE FACTORS ON NEST-SITE SELECTION AND NESTING SUCCESS OF EASTERN BLUEBIRDS (Sialia sialis)

Napper, Kristin M. 23 September 2005 (has links)
No description available.
40

Nesting Ecology of the Dickcissel (Spiza americana) on a Tallgrass Prairie Relict in North Central Texas

Steigman, Kenneth Lee 05 1900 (has links)
Eighty-three species of vascular plants were inventoried on the prairie relict during peak dickcissel nesting. Based on foliar cover and occurrence frequency, the five dominant plants were heath aster (Aster ericoides), eastern gammagrass (Tripsacum dactyloides), little bluestem (Schizachyrium scoparium), sensitive briar (Schrankia roemeriana) and meadow dropseed (Sporobolus asper). Sixty-one percent of dickcissel nests were constructed on or immediately next to three plant species: eastern gammagrass, sensitive briar and green milkweed.

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