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3 - Global Bird Communities of Alpine and Nival Habitats
- Edited by Dan Chamberlain, University of Turin, Aleksi Lehikoinen, Finnish Museum of Natural History, University of Helsinki, Kathy Martin, University of British Columbia, Vancouver
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- Book:
- Ecology and Conservation of Mountain Birds
- Published online:
- 30 June 2023
- Print publication:
- 20 July 2023, pp 90-136
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- Chapter
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Summary
Alpine grassland and nival zones are characterized by variable environmental conditions, compressed breeding seasons, and limited resources such as food and nest site availability. As a result, high elevation habitats around the world contain an impressive diversity of unique bird species, highly specialized to thrive in challenging environmental conditions with limited breeding opportunities. In this chapter, we highlight the global diversity of alpine habitats and avifaunal communities. We first define general features of alpine and nival zones, before providing an overview of these habitats across 10 major regions around the world. Assembling a global list of alpine breeding birds, we then summarize what makes alpine avifauna unique and how communities vary regionally. Specifically, we focus on traits that characterize how species interact with their environment: i) alpine specialization and endemism, ii) nesting strategies, and iii) migration behaviour. Finally, we address some of the main eco-evolutionary drivers that shape these alpine communities, including climate, vegetation structure, food availability, and species interactions. We conclude by discussing the critical role snow dynamics play in maintaining many alpine bird communities and highlight the concerning trends associated with a rapidly changing climate that are putting pressure on alpine birds.
4 - Birds of Treeline Ecotones
- Edited by Dan Chamberlain, University of Turin, Aleksi Lehikoinen, Finnish Museum of Natural History, University of Helsinki, Kathy Martin, University of British Columbia, Vancouver
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- Book:
- Ecology and Conservation of Mountain Birds
- Published online:
- 30 June 2023
- Print publication:
- 20 July 2023, pp 137-175
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- Chapter
- Export citation
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Summary
The mountain treeline forms the ecotone between the forest and the grass/shrub-heath dominated alpine zone and is often a zone of relatively high diversity. We first assess the universality of a peak in bird diversity at the treeline across studies and regions. Defining a ‘treeline’ bird is challenging, as this zone is often a mix of habitats, thus we determine whether any species can be classified as ‘treeline specialists’. We then compare bird communities of different mountain ranges and types of treeline: climate-limited, and those limited by disturbance, including of both natural (e.g. avalanches, grazing by wild herbivores) and anthropogenic (livestock grazing) origin. Furthermore, we assess the extent to which there are commonalities in broad traits (e.g. migratory strategy, foraging strategy, nesting substrate), primary origin (e.g. montane or alpine) and taxonomy (e.g. proportion of passerines vs non-passerines) across different treeline communities. We then review the determinants of reproductive success of treeline birds, the importance of vegetation structure, and the impact of grazing of both domestic and wild animals in maintaining the habitat mosaic. Finally, we consider how key threats to treeline bird communities might be confronted through conservation strategies.