All grouse species inhabiting Swiss mountain forests have been declining and are red-listed or classified as near-threatened, with the Western Capercaillie Tetrao urogallus being of highest concern. However, grouse declines do not reflect a general trend in bird species inhabiting mountain forests. We argue that the Capercaillie's predicament stems from its habitat selection, which is however not fundamentally different from other typical mountain forest birds. The difference rather lies in the fact that it requires higher local structural diversity of forest stands which, at the same time, should extend over larger areas. This is mainly due to life history traits ultimately related to its large body size and sexual size dimorphism. Capercaillie can thus make an excellent umbrella species. It has indeed been demonstrated that Capercaillie presence is associated with higher species richness and abundance of typical mountain forest birds, but not with total bird species richness and abundance. Most likely, Capercaillie can also be seen as an umbrella species for other components of biodiversity ranging from beetles to phanerogames. This is because high structural diversity and conditions allowing enough light to reach the forest floor are beneficial for many groups of organisms. Therefore, managing forests according to the needs of Capercaillie is not to be seen as a onesided policy for the benefit of a popular flagship species but as a useful strategy for enhancing a wider part of biodiversity in mountain forests.