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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

Ecological correlates of anuran breeding activity and community structure

Saenz, Daniel 17 February 2005 (has links)
Multiple ecological factors can simultaneously affect species activity and community structure. The goal of my dissertation was to examine the effects of abiotic factors, biotic factors, and succession on anuran communities. I took a three pronged approach dividing the study into three major chapters. First I focused on abiotic factors that affect anuran breeding activity. I found that weather, rainfall and temperature affect the breeding activity of each species differently, and species in my study area can be placed into 5 different groups based on their association with weather and season: 1) breed within a predictable season (summer) independent of local weather patterns 2) breed opportunistically within a predictable season (summer) dependent on local rainfall 3) breed opportunistically within a predictable season (winter) dependent on local temperature 4) breed opportunistically dependent on local flood level rainfall events and 5) breed opportunistically year round dependent on local temperature in the winter and local rainfall in the summer. In the second part of the study, I created a simulation model of an anuran community using published life history parameters of the anuran species in my study system. Results of the model suggest colonizing ability is important for species with low fecundity and high susceptibility to predation. These early succession species tend to be constrained from later stages of succession by predators. Species that are resistant to predators are generally poor colonizers and tend to arrive late in succession, but once they colonize a pond they tend to persist and recruit successfully. Finally, I explored biotic mechanisms that might be important in structuring anuran communities. I found that with the exception of Rana sphenocephala, anuran species occupying sites with shorter hydroperiods had higher activity rates and were more susceptible to predation. Rana sphenocephala appeared to be better at escaping predation than the other species despite a relatively high activity rate. Examination of published phylogenies indicates R. sphenocephala is derived from a species group that uses permanent water suggesting that R. sphenocephala has retained many anti-predator defenses inherited from its ancestors, even though the species now exploits sites with low predator densities.
2

An evaluation of bird presence and breeding activity in regenerating coastal dune forests, Maputaland, South Africa

Taylor, Martin Russell 17 April 2008 (has links)
Researchers use changes in bird community composition to illustrate ecological succession in restoration studies. These studies utilise a variety of methods, some of which may bias their outcomes. Here I used the point and line transect methods to obtain community compositions as well as to estimate total density, species richness and species diversity for bird communities living in a successional sere of coastal dune habitats. The two methods yielded similar estimates of community variables in the younger regenerating sites with the point transect method giving higher estimates in the older regenerating sites. The line transect method provided higher density estimates than the point transect method across all sites but there was no significant difference between variance estimates for the two methods. The point transect method reached the maximum number of detectable species in half the time that it took the line transect method. In contrast to my expectations, the point transect method proved to be superior in terms of efficiency. Past research suggests that bird presence itself does not reflect on colonisation success. I compared the community composition, variables and age related trends of point transect and breeding assemblages within the study area. The breeding assemblages represented a subset of the point transect assemblage. Age related trends were significantly similar with both assemblages approaching the variables noted on an undisturbed reference site with an increase in regeneration site age. I concluded that presence based surveys of bird communities adequately captured age related trends to make valid conclusions about patterns of succession. / Dissertation (MSc (Zoology))--University of Pretoria, 2008. / Zoology and Entomology / MSc / Unrestricted
3

The movement and landscape use of Blue Cranes in the Western Cape

Davis, Sydney Pierce 21 February 2019 (has links)
The Western Cape population of Blue Cranes (Anthropoides paradiseus) is the largest and most stable population for the species. The population is primarily threatened by high mortality due to collisions with power-lines and the development of wind farms. Yet, little is known about how this population uses the agricultural landscape and their movements. Thirteen Blue Cranes were fitted with trackers to collect Global Position System data and tracked for 3 – 18 months in the Overberg region of the Western Cape. With the provided spatial-temporal information, I estimated the home range size, daily flight distances, and distance travelled throughout the day of breeding and non-breeding cranes to determine whether the breeding status/season influences their ranging behaviour. There was no significant difference of the home range size between breeding cranes and non-breeding cranes (p > 0.05). There was also no significant difference of the home range size of breeding cranes between their seasons (p > 0.05). Breeding cranes travelled significantly shorter daily flight distances than non-breeding cranes (p < 0.05). Breeding cranes also travelled significantly shorter daily distances during the breeding season than the non-breeding season (p < 0.01). All cranes, regardless of breeding status or season, travelled further distances in the morning, decreasing distance during the midday and early afternoon with an increase in the late afternoon. Breeding cranes travelled shorter distances throughout the day than non-breeding cranes during the breeding season (p < 0.001). Lastly, breeding cranes travelled significantly shorter distances throughout the day in the breeding season than the non-breeding season (p < 0.001). From this study the results suggest that factors other than breeding status influence the ranging behaviour of these cranes. Factors such as the availability of roost and forage sites, the agricultural landscape of the Overberg and the presence of other Blue Cranes could also affect ranging behaviour. Although this study does not give clear guidelines on the movement of the population, it establishes a baseline for further studies into factors that affect their ranging behaviour and can still be used to aid in conservation strategies for the species. Future studies should focus on recording their time budgets, including overnight GPS fixes and assessing ranging behaviour over multiple years.
4

Motivace organizovaných dětí a mládeže k chovatelství v České republice / Motivation organized children and youth for breeding in the Czech Republic

JURA, Vlastimil January 2015 (has links)
The thesis deals with the research motivation organized children and youth for breeding in the Czech Republic. The theoretical part describes aspects and effects of pet supplies such as leisure activities. Specific educational aspects of breeding activities in personal development. It also describes the issues and going through breeding for the protection of animals and nature. The practical part includes the preparation and implementation of research organized by the motivation of children and young people from different breeders' organizations operating in the country. It details and comments on the results of the research and is divided according to other criteria. Represents Czech Breeders Association as a volunteer non-profit organization working with children and youth organizing prestigious international competition for young breeders Olympics.

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