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Thesis (Ph. D.)--University of Missouri - Columbia, 1996. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri - Columbia, 1996. / Includes bibliographical references (p. 30-38, 41, 74-77, 107-111, 129-132). Also available on the Internet.

Breeding site fidelity and its effect on reproductive success was investigated in two diving ducks species, i.e. Common Pochard (Aythya ferina) and Tufted Duck (Aythya fuligula) in the Trebon region and the surroundings using caught and individually marked females, searching for nests, and monitoring of marked individuals and its broods. In both studied species, the fidelity ratio (apparent survival, MARK software) was around 65 %. Evaluating the influencing factors, impact of previous reproductive success in the phase of rearing ducklings was found to be the only one statistically significant factor. Furthermore, we compared reproductive parameters (i.e clutch size, laying date, reproductive success) in the first and subsequent year of study. The statistically significant relationship was found between the timing of nesting in the first and in any subsequent year in the Tufted Duck . When comparing the reproductive success in relation to hatched or unhatched clutches and reared or not reared ducklings, we do not confirm any significant shift. Successful females were not able to improve or even repeat their reproductive success in the following years, which could result in subsequent lower degree of fidelity. Subsequently, there is a female dispersion and reduction of the reproductive success of...

During the winters in recent years Laholmsbuktens VA's treatment plant in Halmstad has recorded unexcepted levels of phosphorus from the polishing pond. Only between 8 and 20 January 2016 samples indicates a realese of net 75 kg. In winter the pond temperature never goes below about 8oC, which attracts wintering waterfowl. In February 19, 2016 the largest number of birds in the inventory for this thesis was noted, 325 individuals, of which 208 were tufted ducks.  Even if the number of waterfowl at peak levels was to be about 1000 individuals, their combined contribution of phosphorus through droppings into the pond could not be more than 500 g per day. This study proposes that a significant factor is the foraging activity of tufted ducks, which are diving ducks. In search of food at daytime they disturb the sediment at the bottom of the pond, i.e bioturbation.  The higher proportion of particle-bound phosphorus in samples with high phosphorus content also fits well with this hypothesis. A scientific investigation in which the bottom of this part of the pond was stirred up mechanically gave similar proportions between phosphorus and water-soluble phosphorus.

I investigated differences in egg volumes for two common species diving ducks ? Common pochard (Aythya ferina) and Tufted ducks (Aythya fuligula). I tested selected reproductive and environmental factors with potential influence on egg volume and sex of embryo in clutches. Further, I examined egg volume in connection with the nest parasitism and compared parasitic and non-parasitic eggs in context of egg volume. I also estimated rate of nest parasitism in studied ducks population.

Citizen science offers a potentially powerful tool for the environmental scientist to access large data sets over increasingly greater time scales. Given the ease of which information can be reported or shared online and the increase in community interest there is an overwhelming amount of data available. But two major questions remain; is the data reliable and how is it best used? This study addresses the first question by testing the ability of such data from Artportalen, Sweden’s Species Gateway for reporting observations of birds (and other flora and fauna), to reflect patterns in the presence and absence of breeding records of Tufted Duck (Aythya fuligula) and Eurasian Teal (Annas crecca). This was done by undertaking wetland assessments in a set of constructed wetland sites from Artportalen in Halland, Southern Sweden, with breeding records of the target species. A literature review was also undertaken to explore the existing ecological knowledge of breeding habitat requirements for each species. Physical and biological characteristics from the wetlands visited were then qualitatively compared to the existing ecological knowledge for each species’ preferred breeding habitat. This method resulted in some support for the reliability of this particular Citizen Science data, in that it reflected Tufted Duck’s preference to breed in wetlands closer to the coast, that provided some form of cover or screening around the edges and which had a large proportion of their shoreline bordered by tall emergent vegetation. Conversely, it reflected Eurasian Teal’s preference for inland wetlands that were closer to relatively open natural freshwater bodies, where tall emergent vegetation wasn’t as abundant. How this and other Citizen Science data can be used in the design and management of constructed wetlands for conservation purposes in light of these results is then discussed.

5 Abstract This thesis is aimed at spatial variability of population structure of our four most common and the most numerous species of ducks wintering in the Czech Republic. These analysed species are Mallard (Anas platyrhynchos), Tufted duck (Aythya fuligula), Common Merganser (Mergus merganser) and Northern Goldeneye (Bucephala clangula). The field data were collected by January International Waterbird Census in the Czech Republic between 2004 and 2013. Analysed habitat variables include: type of wetland, altitude, population size, level of urbanisation (size of settlement) and mean January air temperature in the investigated site. There was found no significant effect of type of wetland and local population density on population structure in any of these bird species. The next factor, altitude of sites was confirmed as significant only for Mallards, when increasing altitude decreased proportion of males in the population. Furthermore, effect of urbanization was found also in Mallard, when proportions of males increased with level of urbanization, i.e. in larger cities. Finally, , temperature of sites was confirmed to be significant factor affecting population size in the three analyzed species, i.e. in Mallard, Tufted Duck and Northern Goldeneye. Except Common Merganser, ratio of males grew with...