Site-based adaptation reduces the negative effects of weather upon a southern range margin Welsh black grouse Tetrao tetrix population that is vulnerable to climate change

Climate change is an increasing threat to global biodiversity. Whilst there is growing evidence about the potential effectiveness of some aspects of climate change adaptation, the role for site-based management to increase the resilience of vulnerable populations to climate change has been little studied. Here, we test whether such management may reduce the negative effects of unfavourable weather upon a southern range margin Welsh black grouse Tetrao tetrix population that is vulnerable to climate change. The Welsh black grouse recovery programme funded a range of interventions that contributed to a 39% population increase over 10 years. One likely mechanism linking black grouse populations to climate change is the sensitivity of chicks to high June rainfall. We modelled the relationship between June rainfall and management interventions which aimed to increase breeding success (habitat management and lethal predator control) to test whether management could increase the resilience of black grouse populations to such unfavourable weather. Importantly, we found that the negative effect of June rainfall upon productivity was eliminated at sites where predator control occurred, and that productivity was maximised when predator and habitat management were combined. Active management therefore reduced the negative effects of June rainfall upon this vulnerable southern range margin black grouse population, although further work is required to quantify any limits to the success of such management. Active management should be considered as a tool for climate change adaptation in other vulnerable populations, particularly where there is limited potential for species to undergo climate-driven range changes.