As forest-dwelling species and habitat specialists, Capercaillie and Hazel Grouse are two important bioindicators for studying the impact of environmental change on bird species of conservation concern. Numerous studies about the effects of forest use and climate change on the distribution and abundance of Capercaillie and Hazel Grouse in mountain forests have been conducted at the Swiss Federal Research Institute WSL since 2001. Here, I summarise the most important results of these studies, present it for each species separately and comparatively, complement conceptual aspects of habitat availability in used and unused forests with a new illustration, and finally, provide conclusions for species conservation. Analyses show that climate change should not be underestimated as new and significant threat for the native forest grouse species. This threat can only be partially compensated by an adaptive habitat management for which distinctions should be made for primary and secondary habitat. A management for sympatric occurrence of both species in the same forest is possible. However, the Capercaillie is more dependent on an active, intervention- based habitat management and the Hazel Grouse depends more on a passive, non-intervention management. The predicted increase in storm and wet snow events under climate change can improve the future habitat situation for both species in mountain forests, as natural disturbances increase the stand dynamics and the mosaic of semi-open forest stands. However, this requires that affected areas are not (completely) salvage logged by the forestry service and are naturally rejuvenated. In addition, supporting measures such as the control of human disturbance and predator abundance are required, especially at the lower, more productive sites with mixed mountain forests, so that the habitat measures can achieve the desired effect in terms of a population recovery.