Effects of Habitat and Researchers' Disturbance on Nest Predation of Capercaillie (Tetrao urogallus): an Artificial Nest Experiment in Swedish Forests

Capercaillie (Tetrao urogallus), is a ground-nesting grouse species present in the forests of Europe and Asia. It is considered an umbrella species due to its large habitat requirements, and it serves as an indicator of a healthy biodiverse forest. Capercaillie's global population is declining, and nest predation has been identified as a key factor negatively influencing the population. However, all factors affecting nest predation are not yet fully understood. Here, we use a controlled experiment using artificial eggs to determine capercaillie predators and understand the effect of habitat fragmentation on nest predation. We were also interested in knowing if researchers, by the simple act of visiting nests, affect predation outcomes. We found no statistical significance that habitat diversity, land use, and research visits to nests increase predation. However, our findings reveal that nests located in areas with previous clearcut suffer significantly more predation than those in forest. Thus, we suggest that clearcutting may create conditions that favour general predators, therefore increasing the risk of nest predation. These results demonstrate the importance of managing clearcut practices to minimize nest predation risk for capercaillie. We hope to contribute to understanding how forestry practices influence predator–prey dynamics and offer insights for conservation strategies.