CIC Supports Capercaillie Conservation
The effects of human disturbance on species: A case study on capercaillie
CIC members support research for the world largest grouse species
3 January 2007
Capercaillie populations have significantly decreased in abundance and distribution in major parts of their distribution range. Main factors causing the population decline in Central Europe include changes in forest management, habitat quality and probably, human outdoor activities. However, effects of human disturbance on capercaillie are mainly speculative or subjective since corresponding studies are lacking. In an international co-operation research project, PhD student Dominik Thiel from the University of Zurich and the Swiss Ornithological Institute investigated the susceptibility of capercaillie to human recreation activities.
An indicator of disturbance is the increase of stress hormones in the bird’s body. A new biochemical method allows monitoring the level of stress hormone metabolites in feces. This method has been successfully tested and validated using capercaillie in captivity. A large-scale faeces sampling in Swiss and German capercaillie populations with skiing areas and disturbance-free habitats was conducted to study the physiological stress response. Further, the individual behavioural response of capercaillie to various winter recreation intensities was investigated by measuring flushing distances and habitat use of radio-tracked capercaillie.
The results confirmed that capercaillie are highly susceptible to human disturbance, because the behaviour and the stress physiology of this forest grouse was affected by human winter recreation. Capercaillie in areas with high winter recreation intensities exhibited longer flusing distances and higher stress hormone levels than birds in undisturbed sites. During the ski season, capercaillie preferred undisturbed forest patches, which was not the case before the start of the ski season. These behavioural and physiological responses to winter recreation have high potential to negatively affect capercaillie fitness.
By establishing officially declared wildlife refuges, with prohibited human access and by implementing restrictions for recreationists to stay on-trail in capercaillie core areas, the situation for the capercaillie may be improved upon as human-caused stress is decreased.