• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 5
  • Tagged with
  • 25
  • 25
  • 25
  • 8
  • 8
  • 6
  • 6
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 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

Changes in grassland songbird abundance and diversity in response to grazing by bison and cattle in the northern mixed-grass prairie

Sliwinski, Maggi 21 September 2011 (has links)
There is little information comparing the impacts of bison and cattle grazing in the northern mixed-grass prairies; understanding which grazer to use for management is important. I collected data in sites grazed by bison or cattle using point counts to survey the songbird community, and habitat structure measurements. I used generalized- and non-linear mixed models to determine the relationships between grazers and habitat or songbird communities. Bison and cattle grazing caused changes in habitat structure, including decreased vegetation height and litter depth. Sprague’s pipits declined more steeply with bison grazing than with cattle grazing. 0.4 AUM/ha was an important threshold, because chestnut-collared longspurs increased in abundance at this stocking rate, and grasshopper sparrows decreased in abundance at this stocking rate. Either grazer is appropriate for managing for grassland birds. There is also an opportunity to encourage surrounding landowners to manage their lands for the benefit of wildlife.
2

Changes in grassland songbird abundance and diversity in response to grazing by bison and cattle in the northern mixed-grass prairie

Sliwinski, Maggi 21 September 2011 (has links)
There is little information comparing the impacts of bison and cattle grazing in the northern mixed-grass prairies; understanding which grazer to use for management is important. I collected data in sites grazed by bison or cattle using point counts to survey the songbird community, and habitat structure measurements. I used generalized- and non-linear mixed models to determine the relationships between grazers and habitat or songbird communities. Bison and cattle grazing caused changes in habitat structure, including decreased vegetation height and litter depth. Sprague’s pipits declined more steeply with bison grazing than with cattle grazing. 0.4 AUM/ha was an important threshold, because chestnut-collared longspurs increased in abundance at this stocking rate, and grasshopper sparrows decreased in abundance at this stocking rate. Either grazer is appropriate for managing for grassland birds. There is also an opportunity to encourage surrounding landowners to manage their lands for the benefit of wildlife.
3

Effects of shallow gas development on relative abundances of grassland songbirds in a mixed-grass prairie

Rodgers, Jennifer Anne 02 August 2013 (has links)
Grassland bird species have declined more than birds of any other region in North America, and industrial development may exert additional pressure on these species. I evaluated the effects of natural gas infrastructure on the relative abundances of grassland songbirds in southeastern Alberta, Canada using point counts at sites with well densities ranging from 0 to 20 per 1×1 mile. Generalized Linear Mixed Models were used to evaluate effects of infrastructure on birds, and parsimonious models were selected using Akaike’s Information Criterion. Vegetation near infrastructure was shorter and sparser than locations farther away, but was unlikely to have driven responses to infrastructure by birds. Gas wells may have acted as “artificial shrubs” attracting species such as vesper sparrow (Pooecetes gramineus) and western meadowlark (Sturnella neglecta) that use vegetation for perching, while other species, such as Sprague’s pipit (Anthus spragueii) and chestnut-collared longspur (Calcarius ornatus), had higher abundances farther from wells.
4

Effects of shallow gas development on relative abundances of grassland songbirds in a mixed-grass prairie

Rodgers, Jennifer Anne 02 August 2013 (has links)
Grassland bird species have declined more than birds of any other region in North America, and industrial development may exert additional pressure on these species. I evaluated the effects of natural gas infrastructure on the relative abundances of grassland songbirds in southeastern Alberta, Canada using point counts at sites with well densities ranging from 0 to 20 per 1×1 mile. Generalized Linear Mixed Models were used to evaluate effects of infrastructure on birds, and parsimonious models were selected using Akaike’s Information Criterion. Vegetation near infrastructure was shorter and sparser than locations farther away, but was unlikely to have driven responses to infrastructure by birds. Gas wells may have acted as “artificial shrubs” attracting species such as vesper sparrow (Pooecetes gramineus) and western meadowlark (Sturnella neglecta) that use vegetation for perching, while other species, such as Sprague’s pipit (Anthus spragueii) and chestnut-collared longspur (Calcarius ornatus), had higher abundances farther from wells.
5

The effect of twice-over rotational cattle grazing on the ground beetles (Coleoptera: Carabidae) and spiders (Araneae) on the Yellow Quill Mixed Grass Prairie Preserve

Stjernberg, Anita 11 April 2011 (has links)
The Yellow Quill Mixed Grass Prairie Preserve is a remnant of an endangered community that is located in southwestern Manitoba and owned by The Nature Conservancy of Canada. In 2005 and 2006, this study was conducted to investigate the effect that the currently-practiced twice-over rotational cattle grazing regime is having on the carabid beetles and spiders. This study primarily compared grazed and ungrazed treatments on three paddocks. A secondary experiment investigated whether the spring graze, fall graze, or the combination of the two had the greatest impact on the carabids and spiders. Three periods were examined in three periods each season: before grazing had begun, after the spring graze, and after the fall graze. A total of 81 species of carabids and 156 species of spiders were recorded, including potentially new provincial records (two carabid species and 20 spider species). Seventy two species of plants were recorded in the study.
6

The effect of twice-over rotational cattle grazing on the ground beetles (Coleoptera: Carabidae) and spiders (Araneae) on the Yellow Quill Mixed Grass Prairie Preserve

Stjernberg, Anita 11 April 2011 (has links)
The Yellow Quill Mixed Grass Prairie Preserve is a remnant of an endangered community that is located in southwestern Manitoba and owned by The Nature Conservancy of Canada. In 2005 and 2006, this study was conducted to investigate the effect that the currently-practiced twice-over rotational cattle grazing regime is having on the carabid beetles and spiders. This study primarily compared grazed and ungrazed treatments on three paddocks. A secondary experiment investigated whether the spring graze, fall graze, or the combination of the two had the greatest impact on the carabids and spiders. Three periods were examined in three periods each season: before grazing had begun, after the spring graze, and after the fall graze. A total of 81 species of carabids and 156 species of spiders were recorded, including potentially new provincial records (two carabid species and 20 spider species). Seventy two species of plants were recorded in the study.
7

Relative effects of landscape and local habitat characteristics on grassland songbird abundance and occurrence in southwestern Manitoba

Lockhart, Jessica 14 September 2016 (has links)
I investigated the relative effects of grassland cover and fragmentation per se, and the relative influence of landscape and local habitat characteristics on grasslands songbirds in the moist mixed-grass prairies of Manitoba. In 2013, 361 avian point counts were conducted across 47, 2.4-km radii landscapes in the southwest part of the province. I used an information-theoretic approach to rank and select models describing effects of landscape and local-scale habitat variables on grassland songbird abundance and occurrence. Overall, my results indicate that grassland amount, fragmentation and quality, and matrix composition had relatively small and variable effects on grassland songbird abundance and occurrence, but that abundance of obligate species when pooled showed a strong negative response to grassland fragmentation. While fragmentation through edge effects may contribute to obligate species declines, my results suggest that these factors alone are unlikely to explain ongoing declines of grassland birds in southwestern Manitoba. / October 2016
8

Effects of twice-over rotation grazing on the relative abundances of grassland birds in the mixed-grass prairie region of southwestern Manitoba

Ranellucci, Cristina lynn 16 September 2010 (has links)
The mixed-grass prairie region of southwestern Manitoba is a hotspot for many endangered grassland birds. This region has been degraded to less than a quarter of its historical amount of mixed-grass prairie. Remaining prairie is primarily used for livestock grazing. The objective of this study was to evaluate the contribution of sustainable land management practices, such as rotational grazing, in the conservation of this region. In 2008 and 2009, I compared the abundances of grassland birds on two grazing regimes, twice-over rotation and season-long, to ungrazed fields. Bird surveys were done during the breeding season and were conducted using 100-m fixed-radius point-count plots. I determined the effects of treatment, landscape and vegetation characteristics on songbird abundances using generalized linear mixed models. Grassland birds selected grazed pastures over ungrazed fields in both years, and species richness of obligate grassland birds was significantly greater (α = 0.10) on season-long than twice-over pastures (β = 0.419, p = 0.032, in 2008 and β = 0.502, p = 0.043 in 2009). Season-long grazing may actually benefit grassland bird communities by creating somewhat temporally stable areas of high use and low use within the pasture. However, nesting success studies and long-term monitoring are necessary to further understand how twice-over rotation grazing systems contribute to the conservation of grassland birds in southwestern Manitoba.
9

Using landowner knowledge and field captures to determine habitat use by the northern prairie skink (Plestiodon septentrionalis) on exurban residential land in southwestern Manitoba

Krause Danielsen, Allison Marie 20 April 2012 (has links)
Exurban development, consisting of low density residential housing in a rural setting, is steadily increasing in North America. This increase may have negative impacts on the habitat for some species, through the introduction of non-native plants and new predators such as house cats. The northern prairie skink (Plestiodon septentrionalis) is listed as Endangered in Canada occurring only in southwestern Manitoba. The objectives of this study included: a) defining prairie skink microhabitat use on private land according to vegetation, temperature and cover availability, b) determining landowner awareness of prairie skinks on their property, and c) determining how landowner stewardship could be used in skink conservation. Mixed methods strategy of inquiry was utilized and data collection procedures included both quantitative habitat surveys and qualitative landowner interviews. I found that prairie skinks were most often found in prairie habitat, and were found most often in areas with a) high percent artificial cover, b) high leaf litter, and c) more pieces of cover per acre. Landowners most often saw skinks near buildings, in flower beds and in debris piles. Landowner attitudes towards skinks were positive,though willingness may not translate into action.
10

Effects of twice-over rotation grazing on the relative abundances of grassland birds in the mixed-grass prairie region of southwestern Manitoba

Ranellucci, Cristina lynn 16 September 2010 (has links)
The mixed-grass prairie region of southwestern Manitoba is a hotspot for many endangered grassland birds. This region has been degraded to less than a quarter of its historical amount of mixed-grass prairie. Remaining prairie is primarily used for livestock grazing. The objective of this study was to evaluate the contribution of sustainable land management practices, such as rotational grazing, in the conservation of this region. In 2008 and 2009, I compared the abundances of grassland birds on two grazing regimes, twice-over rotation and season-long, to ungrazed fields. Bird surveys were done during the breeding season and were conducted using 100-m fixed-radius point-count plots. I determined the effects of treatment, landscape and vegetation characteristics on songbird abundances using generalized linear mixed models. Grassland birds selected grazed pastures over ungrazed fields in both years, and species richness of obligate grassland birds was significantly greater (α = 0.10) on season-long than twice-over pastures (β = 0.419, p = 0.032, in 2008 and β = 0.502, p = 0.043 in 2009). Season-long grazing may actually benefit grassland bird communities by creating somewhat temporally stable areas of high use and low use within the pasture. However, nesting success studies and long-term monitoring are necessary to further understand how twice-over rotation grazing systems contribute to the conservation of grassland birds in southwestern Manitoba.

Page generated in 0.0547 seconds