Fragmentation and deterioration of natural habitats comprise major threats to global biodiversity. Especially in areas with a high level of endemism, this degradation can result in the extinction of unique habitats and species. However, some species seem to persist in highly fragmented landscapes and therefore comprise suitable model species to understand how early fragmentation may affect population viability. The ultimate aim of this study is to examine how dispersal and settlement strategies of a small forest-dependent Afrotropical songbird (White-starred Robin, Pogonocichla stellata) vary in relation to habitat quality measured at fragment and landscape level. The study is conducted in the Taita Hills, a highly- fragmented cloud forest in southeast Kenya. The following research themes are addressed:
1. Spatial variation in habitat quality. So far, habitat quality in Taita Hills studies was determined at fragment level. However, intra-fragment variation in vegetation structure is often larger than between-fragment variation. We here examine how habitat quality, invertebrate abundance and bird densities relate at smaller spatial scales.
2. Individual fitness. While bird densities are often used as indicator of overall habitat quality, direct or indirect fitness measurements may better reflect spatial or temporal changes in habitat quality. We here assess levels of mite infestation, fluctuating asymmetry, ptilochronology, hatching and fledging success in relation to habitat quality and individual dispersal and settlement strategies.
3. Dispersal. In spatially-structured populations, long-term viability often strongly depends on the ability to disperse between isolated habitat blocks. Former genetic studies suggested intermediate dispersal rates for White-starred robins, which does not explain how these birds can persist in very small forests. We here use a suite of techniques to estimate intra- and inter-fragment rates of movements and natal dispersal more directly.
4. Settlement. If good-quality territories are scarce, young birds may adopt alternative strategies to take part in reproduction, i.e. they can either compete for suboptimal territories, queue for high-quality territories or adopt floating behaviour. Through a radio-telemetric study of floaters, we aim to link this strategy to habitat and individual characteristics and understand its fitness consequences.
habitat quality, bird density, fitness indicator, feather mite, fluctuating asymmetry, ptilochronology, bird movement, natal dispersal, telemetry, territory floater
|Ecology and genetics of different dispersal strategies of a forest bird in a fragmented Afrotropical cloud forest||partner|
created:2011-12-14 14:18:59 UTC, source:web