Impacts of Human Disturbance on Capercaillie Tetrao urogallus Distribution and Demography in Scottish Woodland

Abstract

Leisure activities in fragmented western European forests are thought to threaten local populations of capercaillie Tetrao urogallus. We studied impacts of human disturbance on capercaillie in three Scottish woods by documenting the distribution of their droppings in relation to woodland tracks and entrances, surrogates for human activity. Droppings were sparser within 300-800 m of entrances and 70-235 m of tracks, depending on track use and habitat. Some 75% of each wood lay within 130 m of a track. In the most disturbed wood, droppings were most abundant in the centres of larger patches of trackless boggy ground, which acted as refuges. The reproductive rate (chicks reared per hen) at our three study areas was no less than in other, less disturbed parts of the same valley. The ratio of full-grown hens to cocks, however, was unusually low in the two most disturbed woods. Disturbance reduces the birds' living space, possibly affecting hens more than cocks. It might therefore impact metapopulation dynamics and contribute to genetic impoverishment in small populations. Ensuring that people and dogs keep to tracks, closing tracks and creating refuges should mitigate such effects.

Outdoor recreation causes effective habitat reduction in capercaillie Tetrao urogallus: a major threat for geographically restricted populations

“…Previous studies also found significant avoidance of recreational trails by capercaillie with distance‐thresholds ranging from 73 m (Summers et al ) up to 125 m (Moss et al ). The threshold values we determined were slightly higher, but in a similar order of magnitude, with mountain bike trails being avoided up to an average distance of 145 m and winter recreation infrastructure up to 320 m. This similarity – despite the studies were performed in different areas using different study methods – indicates that the results might apply to a wide geographical range for capercaillie.…”

“…Recreation activities have been shown to reduce woodland bird densities (van der Zande et al ), bird community composition and nest predation (Miller et al ) or breeding success (Anderson and Keith , Ahlund and Götmark ). Effects of this so called ‘anthropogenic disturbance’ – in this context defined as any form of human presence that triggers one of the above responses in wildlife – varies widely between species (Ficetola et al ), and can differ between sexes in the same species (Baydack and Hein , Moss et al ). Furthermore they strongly depend on the exact type of human activity or even the way humans behave during the same type of activity (Fernández‐Juricic et al ).…”

“…As these regions are at the same time hotspots for outdoor recreation, potential conflicts between human recreation and capercaillie conservation have become a major focus in several management plans (Hennig and Künzl , Braunisch and Suchant ). Various studies showed the sensitivity of capercaillie towards human presence: although Brenot et al () and Moss et al () did not find a significant effect of anthropogenic disturbance on capercaillie reproduction, high intensities of winter recreation have been associated with increased flushing distances (Thiel et al ) and elevated stress hormone levels (Thiel et al , Thiel et al ). Capercaillie have been shown to avoid the vicinity of hiking trails in summer (Moss et al ) and roosting trees close to woodland tracks in winter (Summers et al ), while an overall reduction of local capercaillie densities was recorded in areas highly frequented by recreational activities (Rösner et al ).…”

“…Various studies showed the sensitivity of capercaillie towards human presence: although Brenot et al () and Moss et al () did not find a significant effect of anthropogenic disturbance on capercaillie reproduction, high intensities of winter recreation have been associated with increased flushing distances (Thiel et al ) and elevated stress hormone levels (Thiel et al , Thiel et al ). Capercaillie have been shown to avoid the vicinity of hiking trails in summer (Moss et al ) and roosting trees close to woodland tracks in winter (Summers et al ), while an overall reduction of local capercaillie densities was recorded in areas highly frequented by recreational activities (Rösner et al ). These studies show that capercaillie are influenced by anthropogenic disturbance, however at which scale this affects individual habitat selection, and how these effects translate into effective habitat reduction at the population level, is still unclear (Storch ).…”

Evaluating forest management intensity on an umbrella species: Capercaillie persistence in central Europe

“…Moss et al, 2014;Rösner et al, 2013;Thiel et al, 2011). Human disturbance may influence metapopulation dynamics and contribute to genetic impoverishment in small populations (Moss et al, 2014). For example, collisions with ski-lift cables may increase capercaillie mortality.…”