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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

Reproductive strategies in the common sandpiper Actitis hypoleucos

Mee, Allan January 2001 (has links)
No description available.
2

Breeding biology of the Whooper Swan and factors affecting its breeding success, with notes on its social dynamics and life cycle in the wintering range

Einarsson, Olafur January 1996 (has links)
No description available.
3

A study of colonial organisation of the kittiwake Rissa tridactyla

Fairweather, Jaqueline Anne January 1994 (has links)
Kittiwakes have been studied in detail at North Shields, Tyne and Wear, England since 1954. I investigated die effect of mate change (due to divorce or mate death) on reproductive performance. Below average productivity in the year of divorce and in the preceding year, coupled with a low adult survival rate in the year following divorce, suggested birds which divorced were poorer quality individuals than birds which retained their mate. Productivity was reduced if one or both members of a pair were in their last year of life and was indicative of a decline m fitness. Dispersal, breeding and the importance of nest site tenacity to mate retention were studied when kittiwakes were prevented from returning to their original nest sites in 1991. In 1991, extensive non-breeding (57%) and low productivity resulted. Of die birds which bred, 54 (83%) nested in the immediate colony area and only 11 moved to other colonies. Despite moving site, many birds retained their mate of the previous breeding season. In the following year, a further 61 kittiwakes moved and nested at other colonies and about a third retained theu" mate. This, and other evidence, suggests that individual recognition is important in mate retention. Reproductive performance, in relation to nest position in the colony and proxunity to other nesting pairs, was compared with a kittiwake colony at Marsden, NE England. Productivity was highest at the centre of the colonies and, at the edge, was highest for pairs which nested adjacent to another pair. It is suggested that social stimulation, arising from nesting adjacent to another pair, advanced the date of laying. Adult attendance at the nest during chick-rearing was monitored at Marsden in three years. During comparable time periods ui 1991 and 1993,93% and 75% of die broods, respectively, were attended by an adult, compared to only 51% during the same period in 1992. Attendance decreased in relation to hatching date, chick age and brood size and increased with parental age and/or quality.
4

Relationships among tree-species composition, vegetation structure, and forest breeding birds in southern Illinois

Edmund, Alison 01 August 2011 (has links)
Oaks (Quercus spp.) have dominated eastern forests of the United States for centuries; however, current disturbance regimes discourage oak recruitment and allow shade-tolerant mesophytic species (e.g., maples, Acer spp.) to out-compete oaks. I assessed the effects of mesophication on bird communities by examining differences in breeding bird community structure, abundance, and diversity across 8 and 12 deciduous forest stands in southern Illinois during 2009 and 2010, respectively, using line transects, and by examining a 5-year monitoring data set from across the Shawnee National Forest in 2005-2009. I predicted that variation in bird community structure between maple- and oak-dominated forests can be explained by differential availability of foraging niches. Forest stands used in 2009-2010 were separated along a gradient of hard-mast tree composition, which was defined as the percentage of tree basal area in the stand contributed by oaks and hickories (Carya spp.). Linear regression and Akaike's Information Criteria were used to assess habitat-association models for 7 bird community metrics: bird species diversity, species richness, overall abundance, and abundance of aerial foragers, bark gleaners, foliage gleaners, and ground gleaners. Bird species diversity (Shannon-Wiener H') and species richness ranged from 2.97 to 3.15, and 29 to 37, respectively, over both years. Bird species diversity and species richness were best modeled by a negative relationship with % hardmast tree basal area across both years, whereas overall abundance was best modeled by a positive relationship with understory woody stem diversity. Detection rates for foraging guilds were best modeled by various metrics of habitat structure. Aerial foragers, bark gleaners, foliage gleaners, and ground gleaners responded positively to stem density, downed coarse woody debris density, basal area, and stem diversity, respectively. I used non-metric multidimensional scaling (NMDS) and analysis of similarity (ANOSIM) to examine the degree of dissimilarity among bird communities and site type. In 2010, the bird community differed overall, with communities in oak forests tending (P = 0.09-0.11) to differ those in non-oak and mixed-mesophytic sites. Analysis of a 5-year data set yielded similar results. All models tested for bird-species diversity and species richness were competing, suggesting no individual habitat factor was a strong predictor. Overall abundance and abundance of aerial foragers, bark gleaners and foliage gleaners showed negative relationships to hardmast basal area in all years combined. Ground gleaners responded positively to tree diversity. A post-hoc analysis revealed that overall bird abundance and abundance of foliage-, bark- and ground-gleaning guilds responded positively to an index of riparian areas. Resource use during the breeding season may be shifted to mesic habitats, possibly due to increased resource availability in terms of arthropods and water. Results indicated that mesophication may not have the predicted effects on forest-breeding bird communities, and that vegetation structure was more important in determining bird community structure than tree composition in small-scale forest stands during the breeding season. Resident and over-wintering bird species may be most affected by the loss of oaks due to use during time periods when mesic habitats do not supplement resources. Managers should consider maintenance of a diversity of forest types to maximize avian diversity.
5

Importance Of Agricultural Systems As Multifunctional Landscapes

Sutti, Flavio 01 January 2016 (has links)
Agricultural landscapes provide our society with many benefits. While food production is the primary role of these landscapes, sociocultural and ecological benefits are also provided. However, the full scope of benefits that we obtain from agricultural landscapes are not always taken into account, and with the intensification of agricultural activities, more complex multifunctional landscapes are converted into simpler and less-functional landscapes. I used a heterogeneous agricultural landscape, the Champlain Valley of Vermont, as a case study to examine the interactions between landscape structure and the provision of landscape functions and services. I analyzed sociocultural and production functions indices obtained via standardized landowner surveys, and ecological function indices collected in the field for 51 plots. Plots were clustered into landscape composition categories (forest, mixed and agriculture), and configuration categories (simple and complex). I identified a tradeoff between the production and ecological function in agricultural landscapes. When a rural landscape was managed for intensive agricultural production, ecological benefits decreased. Landscapes with diversified land use/land cover and heterogeneously distributed elements returned the greatest number of benefits. Agricultural areas that comprise between 30 and 45% of the landscape can prevent the loss of ecological benefits while retaining high production. I evaluated the importance of treed habitats in agricultural landscapes in maintaining biodiversity. I related landscape metrics to ecological function indices obtained from fine-grained land use/land cover maps. Metrics obtained from fine-grained maps more accurately predicted the abundance of edge tolerant birds than those obtained from coarse grained maps. I also explored the importance of small treed landscape elements for common breeding birds and evaluated the convenience of monitoring nests comparing temperature loggers to direct observations. More heterogeneous landscapes, rich in small treed elements, supported a greater density of nests. Nests located on small treed elements in agricultural landscapes were as successful as nests located in large landscape elements. These analyses deepen our knowledge about the relationship between landscape structure and function, facilitating the evaluation of the functionality of heterogeneous agricultural landscapes.
6

How does Himalayan Blackberry (Rubus armeniacus) impact breeding bird diversity? : a case study of the Lower Mainland of British Columbia

Astley, Caroline 25 June 2010 (has links)
Awareness of the spread of invasive plant species has grown, but quantitative measures of their impacts are lacking. This study analyses the impact of Himalayan blackberry (Rubus armeniacus) on breeding bird diversity finding a significant difference in bird diversity between “natural” and R. armeniacus-dominated understoreys. More bird species were noted in habitats with greater structural and compositional diversity. Simpson’s richness/evenness index was significantly different between habitat types for Stanley Park and Maplewood Flats (P<0.05) but not Jericho Park (P>0.05), likely due to lower overall bird diversity at Jericho Park and lack of overstorey trees at R. armeniacus thickets. When R. armeniacus is the dominant understorey shrub in a forested setting it has the greatest negative impact on breeding bird diversity.
7

Ptáci řádu Passeriformes otevřené krajiny v CHKO Třeboňsko / Birds of Passeriformes order on CHKO Třeboňsko champaign

FUKA, David January 2008 (has links)
During the breeding season in 2007, the mapping of the nesting ranges in birds of the order Passeriformes was carried out on the chosen localities in Třeboň wet meadows within the Třeboňsko landscape; Aim of study was to order qualitatives and quantitatives status of the Passeriformes within localities and their comparasion. Localities were situated in the immediate vicinity of Třeboň. The total mapped area was 25 hectares. The Vegetation was dominated by tall sedges (locality New station). The principal biotops consisted of tall sedges biotop M1.7 and K1 (locality New station and locality Old station) and V1 biotop. Within Old station locality and Opatovický locality it was especially: T1.5 and T1.4 and X5. Nesting birds were counted by the mapping method (Janda a Řepa, 1989). The GPS system was used for the recording of single males. Twenty three passerine bird species were found within localities. In total, nine bird species were founded in all the localities. The most abundant species were: (Acrocephalus schoenobaenus) the Sedge Warbler, (Luscinia svecica cyanecula) the Bluethroat, (Locustella naevia) the Grasshopper Warbler (Old station locality and New station locality), Opatovický locality was dominated by Acrocephalus schoenobaenus the Sedge Warbler. There was signigicant differences of total density of bird assemblage betwen Opatovický locality and New station locality and Old station locality and Opatovický locality. High breeding density was found especially in the Whinchat and the Bluethroat on New station locality. High conformity of bird assemblage was among New station locality and Old station locality.
8

Brutvögel in Sachsen

Steffens, Rolf, Nachtigall, Winfried, Rau, Steffen, Trapp, Hendrik, Ulbricht, Joachim 14 July 2014 (has links)
Der Atlas behandelt 213 aktuelle und ehemalige Brutvogelarten in Sachsen. Hiervon werden 177 Arten ausführlich mit den Schwerpunkten Verbreitung, Lebensraum, Brutbestand, Phänologie und Brutbiologie sowie Gefährdung und Schutz besprochen. Aus drei Zeitebenen liegen landesweite Bearbeitungen der Brutvogelfauna auf Rasterbasis vor. Die Ergebnisse ermöglichten es, in detaillierten Karten Bestandstrends darzustellen und Veränderungen von Verbreitung und Häufigkeit nachzuvollziehen. 293 Fotos veranschaulichen die Vielfalt der Vogelarten und zeigen ihren typischen Lebensraum.
9

Anthropogenic noise alters avian community composition in temperate forests

Wright, Chelsea Jill 20 August 2018 (has links)
No description available.
10

Bird, Plant, and Herpetofaunal Associations in Cove Forests and Pine Plantations in Mississippi

Posner, Aaron Weston 12 May 2012 (has links)
I investigated plant and animal community characteristics on 14 forest stands in north central Mississippi. Study sites included 9 pine plantations, 3 streamside management zones, and 2 hardwood cove forests. I estimated relationships between faunal metrics and habitat characteristics. I measured vegetation characteristics within quadrant and nested plot designs to estimate understory, midstory, and overstory species composition and structure. I inventoried breeding birds using point count surveys and sampled herpetofauna diversity using area-constrained searches within belt transects during 2008 and 2009. I detected 39 species of birds in 2008, 43 species of birds in 2009, 11 species of amphibians, and 9 species of reptiles. Hardwood cove sites supported more deep forest-dwelling bird and salamander species; whereas, pine stands supported more grassland bird species. Species richness and abundance of birds was related to snag DBH. Species richness and abundance of herpetofauna was related to number of understory plant species.

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