A Highlands bird that is struggling for survival in Scotland is significantly affected by disturbance from winter sports tourism, according to a study that involved radio tracking individuals and measuring the birds' stress-hormone levels.
The researchers say a craze for winter snowshoe walking is having a particular impact on the capercaillie because walkers are able to reach parts of open woodland that off-piste skiers typically don't visit. In some areas, the birds have very few undisturbed refuges left.
The capercaillie is common in Scandinavia and Russia, but clings to survival in Scotland. It numbers 2,758 individuals in Britain, according to the most optimistic estimate from a 2004 survey. It became extinct in Scotland in the 1770s, but was reintroduced to Perthshire in 1837.
The new research studied populations of the turkey-like birds in the Black Forest in southern Germany. The team attached radio transmitters to 13 birds so they could follow their movements. They also collected droppings from the tracked birds and from more than 50 other individuals. The team analysed these for breakdown products of a stress hormone.
They found that the birds avoid areas most heavily used by winter sports enthusiasts. Also, droppings deposited closest to these areas had higher levels of stress-hormone breakdown chemicals, indicating they came from the most stressed birds. The team believes this is an indication of problems for the birds which may lead to difficulties in breeding.
Dr Lukas Jenni of the Swiss Ornithological Institute in Sempach, who led the study, recommends that tourism development in regions inhabited by the capercaillie be halted and more restrictions introduced to prevent tourists from straying away from marked trails.
The RSPB said the results tied in with its studies at Abernethy forest nature reserve in the Cairngorms, the largest remnant of the ancient Caledonian pine forest."This new piece of research does pose questions about how we promote recreation and access in sensitive forests where there are capercaillie," a spokesman said.