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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.
1

Effects of Hardwood Control and Switchgrass Intercropping on Breeding Bird Communities and Resource Use in Managed Loblolly Pine Stands in Mississippi

Fuller-Morris, Marian 10 August 2018 (has links)
Managed loblolly pine (Pinus taeda) stands are common in the southeastern United States and provide young forest conditions for early successional breeding birds. Common pine management practices (e.g. hardwood control) and novel practices (e.g. switchgrass [Panicum virgatum] intercropping), may influence breeding bird use. I evaluated breeding bird abundance, diversity, and resource use within loblolly stands treated to control hardwood species, intercropped with switchgrass, and with no additional management. Hardwood control and switchgrass intercropping both decreased hardwoods and shrubs, and increased forbs. Switchgrass intercropping increased some early successional bird abundances. However, diversity was not different among treatments. Switchgrass intercropping increased 13C:12C in birds and vegetation; both hardwood control and switchgrass intercropping increased 15N:14N in birds and vegetation. Birds moved freely among stands of different ages and management practices. My results suggest these practices improve conditions for some early successional birds and may help maintain ecological value of loblolly stands for birds.
2

Monitoring birds and habitat in early-successional sites in Connecticut

Mazzei, Benjamin A 01 January 2009 (has links) (PDF)
Early-successional bird species are showing alarming declines across the Northeast and particularly in New England. Utilizing limited resources to the best advantage of these declining bird species is a vital task for land managers. In 2006 and 2007, I collected bird abundance and habitat information from 87 points in early-successional habitat in Connecticut. The objective of this effort was to evaluate the relationships between the habitat variables collected at a plot using the point intercept method and the associated bird abundance at the plot. A second objective was to compare two different methods of characterizing early-successional habitat in explaining the variance in bird abundance. A plot-based method based on the BBIRD protocol from Montana Cooperative Wildlife Research Unit and the point intercept method were compared. Finally, I designed and created a database written in Microsoft Access which was used to standardize data entry, aid in the sharing of data and to calculate summary statistics to assist habitat managers in making conservation decisions. The habitat variables were grouped according to composition and structure to analyze bird-habitat relationships. Low broadleaved shrubs, broadleaved shrubs, fern/forbs, conifers, broadleaved trees and invasives, as well as average height for shrubs and trees were used for the analysis. Nine focal early-successional species that are showing general trends of decline were chosen from the list of all birds seen or heard. Bird abundance and detectibility covariates were modeled with the habitat variables using N-mixture models (2004). Up to 24% of the variation of the best models (based upon AICc) was explained by the predictors I investigated. Five of the 9 birds showed a positive correlation to a shrub category variable. Fern/forbs, graminoids and invasives were found to exert less influence on the abundance of these scrub-shrub birds. Results indicated that the date of the survey affected the detectibility of only 5 of the species, and vegetation height only affected one of the species. Overall correlations indicate that these nine shrubland dependent species utilize a structurally complex habitat including broadleaved shrubs less 2 meters in height and than 2-5 meters in height and herbaceous forbs and graminoids. Invasive plants were found to be positively correlated to 2 of the 9 species possibly warranting additional work on the affects of these species on early-successional birds. Thirty-one of the total 87 point count points were selected for the comparison between the BBIRD and point intercept method. I choose six focal early-successional species for the analysis: indigo bunting, blue-winged warbler, chestnut-sided warbler, yellow warbler, prairie warbler and the common yellowthroat. The point intercept and BBIRD methods explained on average the same amount of variability in the data, and models from each data set included nearly the same number of variables, on average. Thus, we conclude these two vegetation sampling methodologies were essentially equivalent in summarizing important characteristics of scrub-shrub bird habitats. In the field, the BBIRD method took on average almost twice as long to complete as the point intercept method. Because in this study the two methods were similar in the amount of the bird abundance variance they explained and because the BBIRD method takes substantially longer to complete, I recommend that the point intercept method be considered an acceptable method for managers to use to characterize the relationships between early-successional bird species and their habitat. An important step in the successful conservation of declining early-successional bird species is the creation of database management systems and the coordination and cooperation amongst agencies that can stem from the use of these databases. The database I created ensures standardized data entry for data collected from multiple sites over many years. The database takes this data and can be queried for whatever particular information a manager needs. Percent cover of vegetation and invasives, average height of vegetation, and bird abundance are summarized and graphically displayed by the database. Ease of operation, ability to query and ability to share the information makes this database an important tool in the successful conservation of declining species
3

Meso-mammal predators and northern bobwhite (Colinus virginianus) occupancy of early successional patches in a managed ecosystem

Fleming, Kelsey 25 November 2020 (has links)
Heterogeneous landscapes made up of variegated patches are common among managed ecosystems, and often provide diverse structural and compositional habitat characteristics. Landscape heterogeneity can affect distribution of resources, competition, and dispersal of organisms over space and time. Therefore, understanding how species respond to dynamic landscapes is necessary when implementing management decisions that foster biodiversity within managed ecosystems. My study uses hierarchical models in a Bayesian framework to quantify effects of landscape context on meso-mammal predators and northern bobwhite (Colinus virginianus) occupancy in an intensively managed loblolly pine forest. Results indicate that edge density can positively influence occupancy of meso-mammal predators, while age of stand, or years since disturbance, can negatively influence occupancy of northern bobwhite. These results further illustrate the importance of considering biodiversity implications when making management decisions.
4

Effect of land-use history and site-specific environmental factors on solitary bees and flower beetles in clear-cuts of boreal coniferous forest

Eriksson, Victor January 2015 (has links)
Land-use history has been recognized as an important factor in shaping biological communities in clear-cuts. Many solitary bees and flower beetles (Cerambycidae: Lepturinae) are commonly found in clear-cuts, which serve as early successional habitats. I analyzed the effect of land-use history on the abundance and species richness, as well as the preference for land-use history in specific species, of solitary bees and flower beetles in coniferous clear-cuts in southern Sweden. Additionally, the effect of site-specific environmental factors was examined. Insects were caught with blue, white and yellow pan-traps in 48 clear-cuts, of which half were meadow and half were forest in the 1870s. With few exceptions, the species found did not show preference for any land-use history. Furthermore, land-use history had no significant effect on the abundance or species richness of solitary bees or flower beetles. This may be due to pan-traps being less attractive in flower-rich locations, a bias in the sampling method. However, species richness and abundance of solitary bees was higher in young clear-cuts (2-4 years old), probably best explained by more exposed soil and higher frequencies of flowering plants in newer clear-cuts. Abundance of flower beetles was higher in old clear-cuts (6-8 years old). This may be due to larger amounts of more strongly decomposed wood in older clear-cuts, which is used in the flower beetles´ larval development. I conclude that solitary bees are likely to benefit if clear-cuts, particularly with meadow history, are kept more open by introducing disturbance regimes, as suggested by previous studies.
5

Evaluation of Private Landowner Intention to Create Early Successional Habitat in Virginia's Appalachian Region

Coovert, Hannah M 01 January 2019 (has links)
As human land uses continue to expand rapidly across the landscape, the management practices of private landowners are an essential part of effective conservation of biodiversity. Conservation of early successional habitats (ESH) and the species that depend on them is a priority in the eastern United States, and efforts to create more ESH on private lands has primarily focused on forest landowners and the harvesting of timber. Private lands with significant pasture cover in a forested landscape present an additional opportunity to create and maintain ESH, yet our understanding of landowner values and attitudes about management strategies in pastures (i.e., modifying mowing or grazing practices, use of herbicides to control invasive species) is lacking. This study implemented a survey of private landowners in five western Virginia counties who own at least 25 acres that are at or above 2000 ft elevation. This region was selected due to its high priority for declining bird species and its mix of heavily forested ridges and extensive pastureland in its valleys. Our primary objective was to understand what influences private landowner intentions to carry out seven different ESH management strategies (i.e. modified mowing, modified grazing, timber harvests within forest, timber harvests at filed-forest border, prescribed fire, use of machinery, and use of herbicides to control invasive species) for the benefit of wildlife in the next five years. General linear models (GLM) were developed to determine whether landowner values, barriers to management, perceived norms, past experience, organizational membership, and demographics predicted the intention to carry out each management strategy in the next five years. Models explained 22-49% of the variation in landowner intention and predictors of intention differed across the seven management strategies. What landowners’ value about their property significantly predicted behavioral intention but was not consistent across the different management strategies. For example, those most likely to modify mowing and grazing tend to value ecological aspects of their land (i.e., pollinator habitat and water quality) whereas those most likely to harvest timber value hunting and revenue from production on their land. Landowner’s past experience with land management was a strong predictor of likelihood to modify mowing and grazing and to harvest timber. Lastly, members of non-hunting conservation organizations are nearly 7 times more likely to modify grazing practices than non-members, and members of hunting conservation organizations were 2.6 times more likely to use prescribed fire for the benefit of wildlife. These results suggest that expanding outreach efforts to include additional management options for creating ESH (i.e., modification of mowing and grazing practices) and the inclusion of images and verbiage about the benefits to pollinator species, non-game species, and water quality would likely recruit landowners who may not have been recruited with current methods.
6

Eastern Whip-poor-will Habitat Associations in Fort Drum, NY

Spiller, Kimberly 02 July 2019 (has links)
The eastern whip-poor-will (Antrostomus vociferus: hereafter whip-poor-will) has been declining from historical population levels throughout its range in the northeast. Although whip-poor-wills have been reported to use a variety of habitats, most recent studies have associated whip-poor-wills with open habitat, such as early-successional habitats or forest edges. Population declines of other early-successional bird species have been attributed to the loss of early-successional disturbance-dependent habitats in the northeast, and it has been suggested that habitat loss is a significant factor in whip-poor-will population declines, as well. However, there remain substantial gaps in our understanding of whip-poor-will habitat associations, and quantitative habitat data in the literature are lacking. As forest management plays an important role in creating and maintaining habitat for many disturbance-dependent bird species, further characterization of whip-poor-will habitat preferences is necessary to determine whether management efforts may benefit this species as well. In order to derive quantitative estimates of habitat requirements, I studied whip-poor-will habitat associations at Fort Drum in upstate New York. In 2015 and 2016, whip-poor-wills were surveyed at night at randomly-selected point count locations and vegetation measurements were collected in the point count radii to relate whip-poor-will occupancy with structural and compositional habitat variables. Whip-poor-will occupancy was strongly related to intermediate amounts of basal area, with values that generally correspond to forest denser than most shrublands, but more open than closed-canopy forest. Occupancy was also related to lower understory height values, which supports evidence that whip-poor-wills may prefer habitat with a relatively open understory. In 2016, I also measured habitat at locations where whip-poor-wills were foraging, roosting, and nesting, to investigate the theory that whip-poor-wills require open habitat for foraging, but more closed habitat for nesting. Ten adult whip-poor-wills were tracked using radio telemetry and vegetation measurements were collected at a subset at these points where the birds were either foraging or roosting during the day, as well as at any identified nest sites. Comparisons of the vegetation measurements revealed that foraging habitat was significantly more open than roosting habitat, as foraging habitat had lower tree density, basal area, and understory height. Contrary to conventional thought, the few nest sites found in this study were in areas that had low basal area, similar to the habitat at foraging locations. The results suggest that while creating more open-canopy habitat may benefit whip-poor-wills by providing suitable foraging habitat, and potentially nesting habitat, maintaining denser forest within proximity to these open areas may also provide valuable cover for roosting whip-poor-wills. In conclusion, I suggest that land owners looking to create or maintain suitable habitat for whip-poor-wills apply forest management treatments that create openings but still maintain intermediate levels of basal area, such as shelterwood or group tree selection. Foraging habitat for whip-poor-wills appears to be generally more open than roosting habitat, both in terms of lower basal area and a more open understory, so having areas where tree and understory removal is concentrated in proximity to areas that are denser may also benefit this species.
7

Factors Influencing Shrubland Bird and Native Bee Communities in Forest Openings

Roberts, H. Patrick 24 March 2017 (has links)
Once prevalent on the landscape, early-successional habitats are now increasingly threatened in the northeastern United States. As a result, many species that rely on or require habitats dominated by shrubs, young trees, grasses, and forbs have experienced precipitous population declines, leading many organizations to list shrubland habitats and constituent wildlife as a conservation priority. Even-aged forest management (e.g. clearcutting) has been shown to be an efficient and effective means for creating early-successional habitat for certain taxa such as shrubland birds, but it is unfeasible in many situations in southern New England due to public opinion and increased parcelization. Group selection harvests create shrubland conditions in the form of relatively small forest openings (< 1 ha); however, limited attention has been directed toward understanding the extent to which these methods contribute to conservation of early-successional species. In order to assess the conservation value of small forest openings for wildlife in southern New England, I studied two distinct communities associated with early-successional habitats, shrubland birds and bees (Hymenoptera: Apiformes), in openings created by group selection harvests and patch-cutting. In 2014 and 2015, birds were surveyed in small forest openings in western Massachusetts in an effort to describe relationships between species occurrence and patch area as well as other microhabitat-, patch-, and landscape-level variables. Black-and-white warblers, common yellowthroats, chestnut-sided warblers, eastern towhees, and gray catbirds were likely to be present in openings at least 0.3 ha in size, while indigo buntings and prairie warblers had minimum area requirements of 0.55 and 1.07 ha, respectively. Variables within microhabitat-, patch-, and landscape-levels were important for predicting species occurrence. Most notably, prairie warblers were more likely to occur in openings closer to large patches of habitat such as powerline corridors, even if those openings were small in size. I conclude that, despite their inability to support the entire community of shrubland birds in this region, small forest openings can provide habitat for several species of conservation concern if proper attention is given to promoting suitable microhabitat, patch, and landscape characteristics. Bees were sampled in openings as well as adjacent mature forest in an effort to describe the bee community, identify environmental variables influencing bee abundance and diversity, and examine the extent to which openings created by forest management may support bees, as well as potentially augment bee populations within adjacent unmanaged forest. Bees were significantly more abundant and diverse in forest openings than mature forest, but species composition was indistinguishable between openings and forest. Abundance and diversity displayed no relationship with opening size in either openings or forest, but were generally positively related to the amount of early-successional habitat on the landscape. Vegetation characteristics within openings were important in shaping bee communities in openings, with abundance and diversity decreasing with vegetation height and increasing with floral abundance. Notably, eusocial, soft-wood-nesting, and small bees exhibited the opposite pattern in adjacent forest, increasing with the succession of openings and decreasing with greater floral abundance within openings. These results suggest that the creation of small forest openings may help to promote bees both in openings and adjacent mature forest, but certain guilds may be negatively affected.
8

Piping Plover (Charadrius melodus) habitat selection, survival, and migration on New York barrier islands following natural and engineered habitat changes

Walker, Katie M. 22 April 2020 (has links)
The piping plover (Charadrius melodus) is an imperiled migratory shorebird that nests on mainland and barrier island beaches on the Atlantic coast of North America. Its population decline was attributed to habitat loss, predation, coastal development, and disturbance. Hurricane Sandy reached the Northeast United States in October, 2012. The storm breached and overwashed two barrier islands of New York that support breeding piping plovers, Fire Island and Westhampton Island. In response to geomorphic island changes, the U.S. Army Corps of Engineers stabilized the islands by filling breaches, building dunes, and nourishing beaches. In accordance with the U.S. Fish and Wildlife Service and the Endangered Species Act, the U.S. Army Corps of Engineers constructed piping plover nesting habitat to mitigate the loss of habitat from engineering. The objectives of this study were to assess habitat selection and quantify suitable habitat before and after Hurricane Sandy and to investigate survival and migration of fledgling piping plovers within their first year. We studied piping plover nest-site selection, habitat, and abundance before (2010) and after (2015) Hurricane Sandy and engineered response. Before the storm, piping plovers selected nest sites (n=62) farther from the ocean (x̄ least-cost distance = 82.8 m) and bay (x̄ Euclidean distance = 697.7 m; x̄ least-cost distance = 24,160.6 m) than would be expected if they were selecting nest sites at random. Following the storm, piping plovers selected nest sites (n=45) that were close to, and had unobstructed walking access to, the ocean (x̄ least-cost distance = 123.4 m) and newly-created bayside foraging habitats (x̄ Euclidean distance = 468.0 m; x̄ least-cost distance = 728.9 m). Areas overwashed by the hurricane contained the most suitable piping plover habitat across all new habitat types. Piping plover abundance increased 93% by 2018 from pre-Hurricane Sandy abundances, with most pairs nesting in new habitats. However, only 58% of suitable piping plover habitat was protected from recreational use and only 4% of piping plovers used unprotected habitats for nesting during 2015–2017. We assessed post-fledging survival with radio telemetry and mark-recapture methods. We banded and monitored 292 fledged chicks from 2013–2018. We affixed nanotags to 43 pre-fledged chicks and tracked them to document mortality on their natal grounds. We used a multi-state open robust design model to estimate post-fledging survival within the first year and migration and return probabilities. Daily survival rate as estimated with nanotags was the same as estimated with mark-recapture methods (0.997). Post-fledging survival did not vary in the six years following the storm, nor did it vary across stages within an individual's first year (0.36; 95% CI = 0.31–0.42). Fledgling migration occurred between July 1 and September 22 and reached its peak between August 15–23 (Ψ = 0.97, 95% CI: 0.92–0.98). Individuals with earlier fledge dates migrated earlier (β = ˗1.51, 95% CI: ˗1.11–˗1.91). Second-year plovers returned to the breeding grounds between February 20 and May 8, with a peak occurring in late April and early May (Ψ = 0.55, 95% CI: 0.41–0.70). Given that newly-created storm and engineered habitats benefitted nesting and brooding plovers, ensuring protection of these and other suitable habitats would likely safeguard fledglings that persist on Fire Island for more than a month before departure. / Master of Science / The federally threatened piping plover (Charadrius melodus) is a migratory shorebird that breeds on sandy beaches along the Atlantic coast of North America. Coastal development, recreational use, and habitat loss are major factors that contributed to its listing under the Endangered Species Act in 1986. Hurricane Sandy reached the Northeast United States in October, 2012. The storm breached and overwashed Fire Island and Westhampton Island, prompting the U.S. Army Corps of Engineers to stabilize the islands by filling breaches, building dunes, and nourishing beaches. Because the islands support a breeding population of piping plovers, the U.S. Army Corps of Engineers also constructed piping plover habitat to mitigate the loss of habitat due to engineering. The objectives of this study were to assess habitat selection of plovers before and after Hurricane Sandy and to investigate survival and migration of fledgling piping plovers within their first year. We studied piping plover nest-site selection, suitable habitat, and abundance before (2010) and after (2015) Hurricane Sandy and engineered response. Before the storm, piping plovers selected nest sites farther from the ocean and bay than would be expected if they were selecting nest sites at random. Following the storm, piping plovers selected nest sites that were close to, and had unobstructed walking access to, the ocean and newly-created bayside foraging habitats. Areas overwashed by the hurricane contained the most suitable piping plover habitat across all new habitat types. Piping plover abundance increased 93% by 2018 from pre-Hurricane Sandy abundances, with most pairs nesting in new habitats. However, only 58% of suitable piping plover habitat was protected from recreational use and few piping plovers used unprotected habitats for nesting. From 2013–2019, we monitored post-fledging piping plovers through their first year. We estimated post-fledging survival and estimated fall and spring migration timing. Post-fledging survival was constant across their first year of life. Fledgling migration occurred between July 1 and September 22 and reached its peak between August 15–23. Individuals with earlier fledge dates migrated earlier. Plovers returned to the breeding grounds between February 20 and May 8 of their second year, with a peak occurring in late April and early May. Given that post-Hurricane Sandy habitats were suitable for plover nests and broods, ensuring protection of suitable habitats would also benefit fledglings that persist on Fire Island for more than a month before departure.
9

Habitat Use By Early Successional Bird Species Along Powerline Rights Of Way: Making Connections Across Private Lands

Peterson, Christine Rose 01 January 2015 (has links)
Wildlife species that rely on early successional habitat are showing long-term region-wide declines, including songbirds such as Eastern Towhee (Pipilo erythrophthalmus), Field Sparrow (Spizella pusilla), Blue-winged Warbler (Vermivora cyanoptera), Golden-winged Warbler (Vermivora chrysoptera), Prairie Warbler (Setophaga discolor), and Brown Thrasher (Toxostoma rufum). All six species are listed as Species of Greatest Conservation Need on a majority of the New England state's Wildlife Action Plans and in 2011, the Golden-winged Warbler was placed under review for federal listing. In areas where vegetation structure is actively maintained in early successional stages, such as powerline rights-of-way (ROWs), there is an opportunity to provide habitat over long time frames. This study focused on habitat use by six early successional bird species in the Champlain Valley in Vermont along powerline ROWs. Thirty sites that included potential habitat were established. During the breeding season, trained citizen scientist volunteers spot-mapped species distribution patterns along transects. Focal habitat use by individuals was mapped during timed field observations (n=83). Vegetation species composition and structure was evaluated within 1m2 vegetation plots across each site (n=965). Logistic regression models of study species' abundance patterns and focal habitat use were compared using Akaike's information criterion (AIC). Surrounding landscape composition, vegetation species composition and vegetation structure had the greatest influence on species abundance and focal habitat use based on best-fit models. All species occurrence, except Blue-winged Warbler and Brown Thrasher, decreased with greater development and fragmentation in the surrounding landscape. While the covariates that influenced habitat use patterns by the species were similar, the effect size and direction of influence varied. These results suggest that a universal management approach for shrubland songbird habitat would not support a broad range of species. The findings from this study determined species-specific habitat preferences that can improve management practices to benefit these declining species.
10

Prairie Warbler Nest-site Selection, Nest Survival, and Demographic Response to Management in a Pitch Pine-Scrub Oak Barren

Akresh, Michael E 01 January 2012 (has links) (PDF)
As shrubland bird populations decline, there is a critical need to understand the effects of habitat management. I studied a population of color-banded prairie warblers (Setophaga discolor) between 2008-2011 in a shifting mosaic landscape within a Massachusetts inland, pitch pine-scrub oak barren consisting of persistent, newly created, succeeding, and disturbed habitats. I present data showing that the abundance and population structure at this site appears to be a function of colonization of newly created habitat by second-year birds, which are likely excluded from mature early-successional habitat by site-faithful older birds. Breeding season fecundity did not differ significantly between newly-created and mature habitats. Birds displaced by mowing or fire dispersed to nearby suitable habitat the following year, had relatively similar reproductive success, and did not negatively affect pairing or reproductive success in adjacent areas. My findings are novel and show that the effects of shrubland management on shrubland birds are beneficial in the short- and long-term. I also examined prairie warbler nest-site selection and nest survival in relation to plant leafing phenology and other factors. Prairie warblers selected distinct nest sites and certain attributes of these selected sites increased nest survival; thus I conclude that nest-site selection is adaptive. Plant leafing phenology influenced nest-site selection and nest survival in this system; its effects on birds should be considered as a potential mechanism by which bird communities can be affected by global climate change.

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