European long-distance migratory birds often change their feathers (moult) in wintering areas. The isotopic profiles in the environment where the moulting takes place can be detected in feathers, making it possible to identify the habitat where the bird was at the time of moulting. European barn swallows from Western Europe migrate south-westwards to their wintering grounds in the Congo Basin (forest habitat), while swallows from Eastern Europe migrate south-eastwards and winter mainly in the savannahs of southern and eastern Africa (open grassland habitat). The two habitats differ in the δ13C isotope percentage. Recent data, supported by the analysis of geolocators, suggest that the Třeboň swallow population is located exactly in the centre of the migration divide - both migration strategies are present. At the same time, barn swallows wintering in the Congo Basin differ from swallows wintering in southern Africa in the δ13C isotope rations in their feathers. The stable carbon isotope profiles of swallow feathers should be analysed in the thesis and the data used to assess: 1) the lifetime consistency of carbon isotope profiles (high consistency would indicate that individual swallows repeatedly choose the same geographical areas (Congo or South Africa) for overwintering), 2) the proportion of individuals migrating to Congo Basic and South Africa in the local population and 3) potential carry over effects of migration – the association between individual condition and fitness with δ13C isotope percentage in feathers. We assume that both migration strategies (south-west, south-east) should be in equilibrium in the centre of the migratory divide and result in the same individual fitness, even though the location of the overwintering site may influence the arrival date and breeding phenology (e.g., assumed earlier arrival from Congo than from South Africa).
Předběžná náplň práce v anglickém jazyce
European long-distance migratory birds often change their feathers (moult) in wintering areas. The isotopic profiles in the environment where the moulting takes place can be detected in feathers, making it possible to identify the habitat where the bird was at the time of moulting. European barn swallows from Western Europe migrate south-westwards to their wintering grounds in the Congo Basin (forest habitat), while swallows from Eastern Europe migrate south-eastwards and winter mainly in the savannahs of southern and eastern Africa (open grassland habitat). The two habitats differ in the δ13C isotope percentage. Recent data, supported by the analysis of geolocators, suggest that the Třeboň swallow population is located exactly in the centre of the migration divide - both migration strategies are present. At the same time, barn swallows wintering in the Congo Basin differ from swallows wintering in southern Africa in the δ13C isotope rations in their feathers. The stable carbon isotope profiles of swallow feathers should be analysed in the thesis and the data used to assess: 1) the lifetime consistency of carbon isotope profiles (high consistency would indicate that individual swallows repeatedly choose the same geographical areas (Congo or South Africa) for overwintering), 2) the proportion of individuals migrating to Congo Basic and South Africa in the local population and 3) potential carry over effects of migration – the association between individual condition and fitness with δ13C isotope percentage in feathers. We assume that both migration strategies (south-west, south-east) should be in equilibrium in the centre of the migratory divide and result in the same individual fitness, even though the location of the overwintering site may influence the arrival date and breeding phenology (e.g., assumed earlier arrival from Congo than from South Africa).