Recent global climate change is influencing the behaviour and ecology of species worldwide. Birds are typical systems to study in this context, as they are often migratory and thus subjected to a variety of environmental effects. This thesis employs the use of long-term ringing records, field observations, historical maps and historical volunteer observations with the aim of describing behavioural and ecological responses of birds to the current environmental change. An investigation into the spring arrival, reproduction and autumn departure in willow warblers (Phylloscopus trochilus) breeding at a southern study site in Sweden (65°N 18°E) showed that all three phenological events had advanced in parallel. Thus birds arrive earlier, start breeding earlier and leave Sweden earlier, with the breeding period staying the same in length. By teasing apart the migratory responses of different individuals, it became clear that particularly early arriving males and early departing juveniles had advanced migration. However, willow warblers migrating past a northern study site in Sweden (65°N 23°E) displayed no change in autumn departure. When migration in the two regionally separate populations were analyzed in relation to climatic variables, the results indicated that foremost a combined effect of growing season onset and the North Atlantic Oscillation influenced migratory timing, and only in individuals that had advanced migration. As growing season onset had advanced at both regions, but only elicited migratory change in southern willow warblers, it is proposed that intra-specific difference between populations prepare them differently to climate change. Willow warblers breeding at northern latitudes were also displaying absence of an otherwise common behaviour of the species: philopatry. It is suggested that the climate induced change in onset of the growing season, coupled with an increase in available territories, could have enabled a southern influx of dispersal-prone birds adopting a less philopatric breeding behaviour. Availability of territories was also studied in southern Sweden, in relation to 100 years of land use change and future climate change effects on forestry. The mass-conversion of grazed forest into coniferous sylvicultures that has occurred in Sweden 1900-2013 was shown to have negatively affected territory availability for willow warblers. The second most common bird species in Sweden, the chaffinch (Fringilla coelebs), was however shown to be largely unaffected. In a future scenario where rising temperatures will increase growth rates of trees, harvest rotation will be faster and both sylvicultures and logged areas will increase in coverage, favouring both species. Thus commonness in terms of landscape and species occurrence has altered historically and is dynamically linked. Historic perspectives were also applied to observations of spring arrival of 14 migratory bird species. A relative comparison of two data sets, collected over 140 years, revealed that short-distance migrants have changed their spring arrival more than long-distance migrants in southern Sweden. In conclusion, the results of this thesis provide insights into climate change effects on avian behaviour and ecology, document unique observations and contribute with a great spectrum of knowledge, from exact details on responses by individual birds, through long-term changes in populations to historical perspectives on shifts in entire landscapes / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p>

Der Buchfinkengesang wurde in Potsdam in zwei Hauptpopulationen über drei Jahre aufgenommen. Jedes Individuum wurde eindeutig am individuellen Strophentypenrepertoire identifiziert. Ein weiterer Punkt der die individuelle Wiedererkennung bestätigt ist die hohe Standorttreue der adulten Männchen. Die beschriebene Methode eignet sich für die Untersuchung von gesamten Populationen, um den Wandel des Gesangs von Populationen in Raum und Zeit zu beschreiben.<br /> <br /> Die Haupterkenntnisse der Arbeit sind:<br /> <br /> - Die Gesamtanzahl der Grundstrophentypen innerhalb einer Population bleibt über Jahre konstant.<br /> - Die relative Häufigkeit jedes einzelnen Strophentyps variiert von Jahr zu Jahr und von Population zu Population.<br /> - Gesangslernen erfolgt exakt mit einem Korrektheitsgrad von mindestens 96%.<br /> - Das Song-Sharing ist innerhalb der Population hoch. <br /> Die diskutierten Mechanismen für das Song-Sharing sind: Die Lebenserwartung, das Zugverhalten, das Lernverhalten, die Etabliertheit von Strophentypen, Weibchenpräferenzen und die Reaktionen der territorialen Männchen.<br /> - Weiterhin wurde ein Modell zur kulturellen Evolution des Buchfinkengesangs programmiert, um die Rolle der Einflussfaktoren, wie Fehlerquote, Abwanderungsrate und Laufzeit zu ermitteln.<br /> Der Wandel des Dialektes erfolgt graduell in Raum und Zeit. Daher sind keine scharfen Dialektgrenzen anzutreffen. Trotz dieser Tatsache markieren die etablierten Strophentypen die Population.<br /> 50 % der Juvenilen siedeln am Geburtsort, auf diese Weise bleibt der Dialekt erhalten und Inzest wird vermieden.<br /> -Analysiert man das Repertoire benachbarten Männchen bei isolierten Alleen, so entspricht die Gesangsangleichung in etwa dem Zufall.<br /> -Intraindividuelle Vergleiche der quantitativen Parameter des jeweiligen Strophentyps wurden saisonal und annuell durchgeführt.<br /> Saisonal konnten für einen Strophentyp ein Trend ermittelt werden. Bei jährlichen Vergleichen konnten intraindividuell ausschließlich nicht signifikante Ergebnisse ermittelt werden, wohingegen die interindividuelle Variation in zwei Fällen signifikant war. In einem Fall bestand ein Trend und in einem weiteren Fall war die Variationsunterschiede nicht signifikant.<br /> - Der Verlauf der Brutsaison lässt sich an der jährlichen Gesangsaktivität nachvollziehen. / Chaffinch song was recorded in Potsdam in two major populations of chaffinches over a period of three years. Each male was identified unambiguously because of their individual song type repertoires. These are usually easy to distinguish from sonagrams as the variation is discontinuous. A further point for individual recognition is the fixed territorial behaviour of adult males. The described method is employed to examine whole populations and to observe changes with space and time in the song of a population. <br /> <br /> The major findings of the study are:<br /> <br /> - The total amount of basic song types in each population is constant over years.<br /> - The quantity of each basic song type is different and varies from year to year and from population to population.<br /> - Song copying is extremely accurate on at least 96% of occasions.<br /> - Song-type sharing is high within populations. Discussed mechanisms for song neighbourhoods are: expectation of life, semi-migratory behaviour, learning skills, establishment of song types, female choice and male vs male interaction. Furthermore a model of cultural evolution of chaffinch song was programmed to determine the role of factors like error rate, rate of emigration and running time. The changes are gradual in space and time. Hence the dialect borders are smooth. Despite this fact established song types mark the population. As every second juvenile bird settles in the population of his birth inbreeding is avoided and the dialect structure is retained.<br /> - Analysing the repertoires of neighbouring males (&ldquo;next door neighbours&rdquo;) in isolated avenues to examine mutual influences suggests that these have the same amount of song types in common than would be expected by chance.<br /> - Within intraindividual comparisons the quantitative parameters of the same song types remain seasonal and annual constant, whereas interindividual variations within the same song tip are statistically significant.<br /> - The breeding biology of the chaffinch can be observed by seasonal singing activity during the breeding cycle.