• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 141
  • 39
  • 23
  • 15
  • 10
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • Tagged with
  • 321
  • 64
  • 45
  • 44
  • 41
  • 41
  • 41
  • 41
  • 39
  • 33
  • 30
  • 26
  • 26
  • 26
  • 25
  • 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.
51

Rizika hnízdní predace čejky chocholaté: vliv krypse hnízd a koloniality / Nest predation risks in Northern Lapwing: the influence of nest krypsis and coloniality

ŠTOREK, Vladimír January 2011 (has links)
This study is dealing with questions of environmental influences on predation risk in Northern Lapwings nests. I for example measured and evaluated nest krypsis and counting nest densities. I as well did marking of nests and dealed with question whether it has influence on nest predation. Another part of this resech was identifying of Lapwings nests predator.
52

BREEDING PRODUCTIVITY, NEST DISTRIBUTION, AND POPULATION ECOLOGY OF WOOD DUCKS IN FLOODPLAIN AND UPLAND FORESTS OF SOUTHERN ILLINOIS

Anderson, Robert Gray 01 May 2010 (has links)
Wood ducks are thought to depend on mature hardwood forests juxtaposed with palustrine wetlands but these habitats have been continuously degraded or destroyed since European settlement. Wood ducks are adaptable and the use of marginal habitats and nest boxes has extended their range and probably was important to the recovery of wood duck populations. Until now no study has analyzed the contribution of upland nesting to local population growth and maintenance. I investigated predation effects on nest site selection using wood duck nests and simulated nests placed in natural cavities. Using demographic data collected on wood ducks in southern Illinois, I created a population model to compare growth rates of population segments that nested in upland and floodplain habitats. During 1993-1998, 179 of 244 radiomarked hens remained on the study area as resident hens. One hundred-four nests were located by following radiomarked hens and 66% of nests were found in upland forests. Nests in the floodplain were initiated earlier than nests in the upland. Thirty-six percent of known nest cavities were used in subsequent years but <10% were used by the same hen. Nest success was greater in upland habitats (0.78 ± 0.10) than in floodplain habitats (0.54 ± 0.18). Hen survival through the nesting season was 0.80 ± 0.03 and did not differ between habitats or age classes. Sixty-five percent (n = 43) of simulated floodplain nests were destroyed compared to 33% (n = 45) in the upland. Logistic regression models of simulated nest data indicated cavity security could be important in the fragmented floodplain forests of Union County Conservation Area (UCCA). No physical characteristics of wood duck nest cavities differentiated successful and unsuccessful nesting attempts. The growth rate of the local population was positive and estimated to be about 3%. Lambda was most sensitive to upland nesting parameters and floodplain parameters appeared to have little impact on lambda. Hens nesting in the area appear to have adapted to predation pressure by nesting in more secure floodplain cavities at UCCA or by nesting in the upland habitats. Floodplain and upland habitats are ecologically intertwined and the local wood duck population would not survive if either habitat were destroyed or severely degraded.
53

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.
54

Overcoming Speech Anxiety in the Classroom

Rogland Harutunian, Erik January 2017 (has links)
Speech anxiety is an issue that persists and presents itself innumerably in schools, especially affecting students who learning English either as their second language or as a foreign language. Speaking anxiety may stem from different sources and affect each individual student differently. The research question that is key to this research is “How can teachers support students who are struggling with speech anxiety?”The research for this thesis has been done through the use a qualitative interview with two secondary school teachers in Lund. The interview was structured after a semi-structured style to allow for guided questions and openness of any unexpected questions and answers during the interview process.The results of this research is that that tackling speaking anxiety in the classroom is no easy feat, although, from the literature and interview content it has been made clear that for a teacher to be successful in supporting their students, being prepared for possible difficulties, composed for sudden changes to lesson plans, and ready to adapt assignments where speaking is involved in order to allow students to be most comfortable and given their utmost honest performance while speaking in front of others.
55

The effects of oil and gas development on songbirds of the mixed-grass prairie: nesting success and identification of nest predators

Bernath-Plaisted, Jacy 14 January 2016 (has links)
Over the past century, populations of North American grassland songbirds have declined sharply as a consequence of habitat destruction. Alberta’s mixed-grass prairie constitutes Canada’s largest remaining tract of native grassland. However, this region has recently undergone a rapid expansion of conventional oil and natural gas development, and few studies have documented its effects on songbird nesting success. During the 2012-2014 breeding seasons, I monitored 813 nests of grassland songbirds located at sites that varied with respect to presence/absence, distance from, and types of oil and gas infrastructure (pump jacks, screw pumps, compressor stations) and gravel roads. Nest survival was significantly lower at infrastructure sites relative to controls for both Savannah sparrow and vesper sparrow. Additionally, vesper sparrow nest density was greater within 100 m of structures. These findings suggest that habitat disturbance caused by infrastructure may result in increased frequencies of nest predation at multiple spatial scales. / February 2016
56

Game of Thrones : Direct Fitness through Nest Foundation in the Primitively Eusocial Wasp Ropalidia Marginata

Brahma, Anindita January 2017 (has links) (PDF)
Reproduction is the avenue for gaining direct fitness. But in certain species some individuals do not reproduce, instead gain indirect fitness by helping relatives to reproduce; the prime examples for this come from the worker caste of social insects like ants, bees and wasps. For explaining such a perplexing paradox, also known as altruism, W.D. Hamilton proposed that individuals can gain fitness in two ways: directly, by reproducing (direct fitness), and indirectly, by helping relatives to reproduce (indirect fitness). Indirect fitness has since been the main focus for explaining the evolution of workers while usually overlooking the fact that workers can also gain direct fitness. One of the avenues for gaining direct fitness by workers is nest foundation and we have studied this phenomenon in a primitively eusocial wasp Ropalidia marginata. We found that workers routinely leave their natal nests to initiate new nests either alone or with a few other wasps. Before leaving their natal nests, such workers prepare in several ways for nest foundation, like enhancing their nutrient reserves and forming outside nest aggregations to engage in dominance interactions. Next, we investigated the emergence of cooperation and division of labour in newly founded nests and how these affect the productivities of the new nests. We found that while two wasps are sufficient for the emergence of cooperation and reproductive division of labour (DOL), it takes three wasps for non-reproductive DOL to emerge; cooperation and reproductive DOL are not sufficient for increasing colony productivity which comes about only with the addition of non-reproductive DOL. Finally, we found that it is ageing and nutrition, and not work done towards gaining indirect fitness that affect workers’ potential of gaining future direct fitness by independent reproduction via nest foundation, in other words, current indirect fitness is not incompatible with future direct fitness.
57

Seasonal Habitat Selection by Greater Sage Grouse in Strawberry Valley Utah

Peck, Riley D. 09 December 2011 (has links) (PDF)
This study examined winter habitat use and nesting ecology of greater sage grouse (Centrocercus urophasianus) in Strawberry Valley (SV), Utah located in the north-central part of the state. We monitored sage grouse with the aid of radio telemetry throughout the year, but specifically used information from the winter and nesting periods for this study. Our study provided evidence that sage grouse show fidelity to nesting areas in subsequent years regardless of nest success. We found only 57% of our nests located within the 3 km distance from an active lek typically used to delineate critical nesting habitat. We suggest a more conservative distance of 10 km for our study area. Whenever possible, we urge consideration of nest-area fidelity in conservation planning across the range of greater sage grouse. We also evaluated winter-habitat selection at multiple spatial scales. Sage grouse in our study area selected gradual slopes with high amounts of sagebrush exposed above the snow. We produced a map that identified suitable winter habitat for sage grouse in our study area. This map highlighted core areas that should be conserved and will provide a basis for management decisions affecting Strawberry Valley, Utah.
58

An investigation of the house building behaviour of Trichopteran larvae

Hansell, Michael Henry January 1966 (has links)
No description available.
59

Breeding Ecology of Noethern Pintails in Prairie Landscapes: Tests of Habitat Selection and Reproductive Trade-Off Models

2011 November 1900 (has links)
Ecologists and conservation biologists are interested in explaining why animal abundance and reproductive success vary among habitats. Initial motivation for this research arose from concerns for Northern Pintail (Anas acuta) populations in North America. Unlike many prairie-nesting dabbling duck populations, pintails failed to increase during periods of excellent wetland conditions, and remained below conservation goals. Low pintail populations have been linked to degraded landscape conditions on the Canadian prairies. Current habitat management for pintails aims to protect and create larger areas of perennial cover either by encouraging better management of grazing lands, by converting cropland to grassland, or by promoting adoption of fall-seeded crops like winter wheat. The central premise is that larger areas of natural grassland cover will attract breeding pintails to nest earlier in the season in low-predation-risk habitat. I studied pintail nesting ecology near the Milk River Ridge, Alberta, 2004-2006, in terms of a life-cycle perspective, from spring arrival and settling on breeding areas, to assess age and quality of nesting females, to determine timing and investment in reproduction, and finally to measure nesting success. A gradient in presumed high (grassland) to low (agriculture) habitat quality provided a landscape template for testing habitat selection models. Pintail breeding pair densities were 1.5-3 times higher in grassland than agricultural landscapes in all three years, regardless of regional population size, with pairs occupying grassland landscapes at higher densities immediately upon arrival in early spring. Northern Shoveler (A. clypeata), gadwall (A. strepera) and blue-wing teal (A. discors) had similar settlement patterns as pintails, but mallard (A. platyrhynchos) pair density was higher in agricultural areas. Relatively more, older female pintails were captured at nests in grassland landscapes whereas yearling females were encountered more often in agricultural areas, a pattern that was not detected in female shovelers. This response suggests that older female pintails may be better able to recognize and settle in higher quality grassland habitats. Body mass of pintail females did not vary among years, decreased seasonally, and was positively related to body size index and incubation stage. Furthermore, pintail body mass did not differ between grassland (650 ± 24 g), ecotone (678 ± 27 g) and agriculture (672 ± 33 g). In female shovelers, body mass varied among years (555 ± 29 g in 2004, 481 ± 18 g in 2005, 508 ± 21 g in 2006), and increased with nesting date. Shoveler body mass did not differ between grassland (519 ± 32 g), ecotone (519 ± 44 g), or agriculture (507 ± 35 g). Nest initiation dates did not vary by landscape for pintail, shoveler or mallard, but all species nested earlier in 2006 versus 2004. In pintail, shoveler and mallard, clutch size was negatively related to nest initiation date. Pintail and shoveler clutch sizes were generally larger in a wet year with abundant wetlands (2006) when compared with a dry year (2004), but no landscape differences were detected. Mallard clutch size did not vary by year or landscape. Female reproductive timing and investment (in terms of clutch size) were unrelated to upland habitat characteristics, counter to a hypothesis that predicts larger pintail clutch sizes in agricultural landscapes. However, pintail and shoveler invested in larger clutches in 2006, a wet year with abundant wetlands, possibly due to greater abundance of aquatic foods. Finally, nest survival rates of duck species, except mallard, tended to be higher in grassland landscapes and lower in agricultural landscapes. Pintail nest survival was consistently higher in grassland than in agricultural landscapes and was highest in 2006 when wetland conditions were excellent. Shoveler and blue-winged teal nest survival rates did not vary strongly with landscape, but were also higher in 2006, whereas mallard and gadwall nest survival estimates did not vary with landscape or year. Overall, pintails settled at higher densities in grassland landscapes where breeding success was higher (indexed by nesting success). This suggests that pintails respond appropriately to cues that enable them to recognize suitable habitat, at least in regions where large contiguous areas of grassland habitat remain. Furthermore, assuming that findings for pintails reflect those of other grassland bird species, large remnant areas of intact natural grassland seem particularly in need of protection or restoration, and management regimes that maintain their habitat integrity. By integrating applied and theoretical aspects of pintail reproductive ecology, I attempted to provide deeper insights into the processes that could shape behavioral decisions by breeding pintails and other duck species. Older pintails may occupy wetlands in higher quality grassland habitat early in spring, forcing subordinate or later-arriving individuals into poorer quality habitat (i.e., where nesting success is lower); however, mechanisms involved in this putative process are unknown. Overall, results suggest that grassland restoration or enhancement (e.g., managing grazing intensity) could improve reproductive success of pintails and possibly other grassland bird species.
60

Lack of aggression and apparent altruism towards intruders in a primitive termite

Cooney, Feargus, Vitikainen, Emma I. K., Marshall, Harry H., van Rooyen, Wilmie, Smith, Robert L., Cant, Michael A., Goodey, Nicole 09 November 2016 (has links)
In eusocial insects, the ability to discriminate nest-mates from non-nest-mates is widespread and ensures that altruistic actions are directed towards kin and agonistic actions are directed towards non-relatives. Most tests of nest-mate recognition have focused on hymenopterans, and suggest that cooperation typically evolves in tandem with strong antagonism towards non-nest-mates. Here, we present evidence from a phylogenetically and behaviourally basal termite species that workers discriminate members of foreign colonies. However, contrary to our expectations, foreign intruders were the recipients of more rather than less cooperative behaviour and were not subjected to elevated aggression. We suggest that relationships between groups may be much more peaceable in basal termites compared with eusocial hymenoptera, owing to energetic and temporal constraints on colony growth, and the reduced incentive that totipotent workers (who may inherit breeding status) have to contribute to self-sacrificial intergroup conflict.

Page generated in 0.0242 seconds