Thesis (Ph. D.)--University of Tartu, 2004. / Includes reprint of 6 previously published articles. Includes bibliographical references.

Greenfinch plumage varies both between and within age and sex classes. This study looked at the possible causes and consequences of this variation in a colour-ringed population. Plumage colour was both repeatable and heritable. The function of colourful plumage in the breeding season was reviewed. Many aspects of the breeding biology of Greenfinches were studied and the effects of plumage on breeding success investigated. Brightly coloured birds seemed to have greater reproductive success than dull ones. Brightly coloured males were also more likely to ret urn to the study area in the following breeding season. Greenfinches are usually regarded as monogamous, but I found that over 25% of nests involved polygamy. Polygyny, polyandry and possible cases of polygynandry were recorded, but polygyny was the most common of the three. It was demonstrated that the experimental provision of food influenced the occurrence of polygyny. The literature generally considers polygyny to be bad for females, however in Greenfinches polygynous pairs were as successful at producing independent offspring as monogamous pairs. Polygynous birds recruited more offspring into the local population than monogamous birds, although this may reflect differences in dispersal. Since polygynous males were bright and had better survival and since colour was found to be heritable, females may have been choosing males for their good genes. If colour is an honest signal, there must be some cost preventing dull birds from becoming bright. Bright Greenfinches were more likely to be killed by Sparrowhawks during the summer than dull Greenfinches and they were also more likely to be injured. In comparison, dull birds were more likely to be killed by Tawny Owls in the winter. Whether Greenfinch plumage variation acted as a "badge of status" over the winter was investigated. The brighter a Greenfinch's plumage the more likely it was to win confrontations at a bird table in the winter, regardless of food type (contra Maynard Smith & Harper 1988). So what influenced a Greenfinch's plumage? Birds with damaged feathers only regrew bright plumage if they were in good body condition. Birds with low fat stores regrew paler feathers after damage, which is possibly related to the fact that the carotenoid pigment is stored in fat. Therefore, it is possible that after the breeding season good quality nales recovered faster, put on more fat and acquired brighter plumage in the moult. Plumage variation in the House Sparrow was also investigated. In hand estimates of bib size were correlated with spectrophotometric estimates of melanin content. Bib size was not related to organ size. The results of this study are compared with the literature on status signalling . It is argued that badges are handicaps i.e. uncheatable signals of individual quality, rather than being arbitrary signals or signalling Resource Holding Potential.

Proefschrift--Utrecht. / Summaries in Dutch and English. "Stellingen" laid in. "Geraadpleegde literatuur":p. [56]-62.

Innerhalb des Zeitraumes 2002 bis 2004 wurden in Berlin Untersuchungen zur Nahrungsökologie verschiedener Vogelarten durchgeführt, wobei auch die Konsequenzen wie der Fortpflanzungserfolg analysiert wurden. Neben der Aufnahme der Brutvogel- (2002) und Wintervogelgemeinschaft (2002/2003) auf fünf Pf à ca. 20 ha entlang eines Urbangradienten, wurden die Arten Blaumeise, Grünling, Haussperling und Turmfalke speziell untersucht. Auf den fünf Pf, die sich hinsichtlich Baustruktur, Flächennutzung und Vegetationsanteil unterschieden, wurden 35 Brutvogelarten festgestellt. Anhand der Artenzahlen ist deutlich ein Urbangradient zu erkennen: Das Stadtzentrum (Ze) wies 12, das Gewerbegebiet (Ge) 15, die Hochhaussiedlung (Ho) 17, die Einfamilienhaussiedlung (Eh) 18 und der Park (Pa) 28 Arten auf. Im Verlauf der Wintervogelkartierung wurden insgesamt 3763 Individuen in 30 Arten registriert. Im Pa wurde bei der Blaumeise der höchste Reproduktionserfolg mit knapp 5,9 Ausgeflogenen/Brut festgestellt. Anhand des Zustandes der Nestlinge und des Fortpflanzungserfolgs sowie durch die Dokumentation des Fütterungsverhaltens der Altvögel anhand von Camcorderaufnahmen wurde deutlich, dass das Nahrungsangebot für die Meisen im Pa am besten war. Der carnivore Turmfalke wurde 2002 bis 2004 unabhängig von den fünf Pf an zehn Nistkastenstandorten untersucht, die in drei unterschiedlichen Zonen lagen: City (Ci), Mischgebiet (Mi) und ländliche Zone (LZ). Als Besonderheit wurden in jedem Nistkasten in der Ci in jedem Jahr anthropogene Nahrungsreste, z. B. Kotelettknochen, gefunden, was zeigt, dass sich der Turmfalke, neben der Nutzung von Gebäuden als Nistplatz, auch hinsichtlich seiner Nahrungsökologie an den Menschen anpasst. Dass die Blaumeise, der Grünling und der Haussperling insgesamt in Berlin gut zurechtkommen, selbst in der Innenstadt, indiziert die Beutetierliste des Turmfalken: Der Haussperling stand an erster Stelle, der Grünling an zweiter und die Blaumeise an sechster Stelle der gefangenen Vogelarten. Besonders in einer Metropole wie Berlin besteht weiterer Forschungsbedarf, da die Synurbanisierung verschiedener Vogelarten ständig voranschreitet. / From 2002 to 2004 the feeding ecology of different bird species was studied in Berlin. Thereby consequences like the success in reproduction were also examined. Beside the survey of the breeding bird (2002) and the winter bird community (2002/2003) in five study sites each covering an area of approx. 20 ha along an urban gradient, the species Blue Tit, Greenfinch, House Sparrow and Kestrel were researched in detail. In total, 35 breeding bird species were found in the five sites, which were characterised by different building structure, land use and vegetation cover. Considering the species` number, an urban gradient was clearly visible: In the city centre (Ze) 12 species were recorded, in the industrial area (Ge) 15, in the high-rise apartment building area (Ho) 17, in the detached family housing (Eh) 18 and in the park (Pa) 28 species. During the winter bird census a total of 3,763 individuals and 30 bird species was recorded. In the Pa, the highest reproduction success of the Blue Tit (5,9 fledglings/brood) was recorded. On the basis of the nestlings'' condition and the reproduction success, as well as by documentation of the feeding behaviour of the adult birds by means of video recording (camcorder), it became clear, that food supply was best in the Pa for the Tits. From 2002 to 2004, the carnivorous Kestrel was examined independent from the five study sites at ten nesting sites (nest boxes), which were located in three different zones: City (Ci), Mixed Zone (Mi) and Outskirts (LZ). Striking were anthropogenic food items, like cutlet bones, found in every nest box in the Ci in all three years, which shows the adaptation to humans not only with regard to nesting sites (buildings) but also with regard to feeding ecology. The prey species list of the Kestrel indicates that Blue Tit, Greenfinch and House Sparrow get along well all in all, also in the city centre: the House Sparrow ranked first, the Greenfinch second and the Blue Tit sixth of the captured bird species. Especially in a metropolis like Berlin there is need for further research, because the synurbization of different bird species progresses permanently.