Capercaillie are critically endangered in Scotland, with welfare concerns centred on disturbance during lekking and breeding, predation pressure, and habitat fragmentation.
Capercaillie welfare at the UK's most critically endangered bird population reflects the compound effects of multiple stressors on a species at the edge of viability. Individual capercaillie welfare during lekking season is particularly sensitive to human disturbance: males displaying at leks have elevated stress hormones that are further elevated by disturbance, which can interrupt display behaviour and reduce mating success. Repeated disturbance of leks has been shown to cause abandonment of traditional sites, with males failing to return the following season. The welfare of females during incubation and chick-rearing is affected by predation pressure that creates sustained alertness and interrupted foraging. Deer fence collisions, where capercaillie fly into forest fencing at high speed, cause acute welfare harm and represent a significant annual mortality source that is directly preventable through fence removal or marking. The combination of disturbance, predation, and habitat fragmentation creates a welfare crisis in which every individual bird's survival is conservation-significant. Welfare improvement and conservation recovery are completely aligned in this case - any intervention that improves individual bird welfare also improves the population's prospects.