Capercaillie puts a spoke in the wheels of mountain bikers

The world's mountain biking fraternity has been stopped in its tracks by an insurmountable problem, a solitary bird and its droppings.

Plans for a bike centre in the Cairngorms National Park at Glenmore, near Aviemore, have been scuppered by the discovery of excreta from the protected capercaillie. There are thought to be only 1,000 breeding pairs in Scotland, most in and around the pine forests that surround Aviemore. Despite finding evidence of only one female bird, conservationists have to assume there is a breeding pair.

With the bird already extinct in most other areas, the risk of upsetting its delicate environment has meant Forest Enterprise has had to cancel its £200,000 project to build 13 miles of tough terrain trails by Sluggan Pass, at the north end of Glenmore Forest.

Scotland is ranked with Montana and Alaska as a choice destination for mountain bikers, thanks mainly to work by the Forestry Commission, local landowners, council authorities and tourist boards to develop graded trails. The International Mountain Biking Association, based in Colorado, says Britain is fast becoming the "hottest mountain bike destination in the world".

Development of the 400-hectare Glenmore site has been abandoned after years of negotiations and wrangling over environmental concerns. A similar centre planned for a site at Inshriach had already been shelved because of concerns over the possible impact on the capercaillie, regarded as one of Scotland's greatest extinction risks.

Kenny Kortland of the RSPB said: "The capercaillie is an amazing bird, the size of a turkey and the biggest grouse in the world. At this time of year, when males are displaying to the females, they are charged full of testosterone and they have attacked humans. With their powerful beaks they can easily draw blood. Strathspey is the remaining stronghold of this species, and the Forestry Commission has an obligation under domestic and EU law to protect the capercaillie."

The Glenmore project, which also included plans for a BMX fun park, café and shop with parking for 70 cars, was expected to attract more than 50,000 visitors a year, providing hundreds of thousands of pounds to the local economy.

David Jardine of Forest Enterprise said: "If you look at the number of cyclists who use other tracks it is easy to see the disturbance caused, and we would be reasonably sure capercaillie would leave the area and would not breed here. It is a bitter-sweet discovery, because it shows capercaillie are still surviving in this part of the forest and, given the national decline, everything must be done to help their recovery."

With more than two million mountain bikes, worth more than £500m, sold in Britain every year, mountain biking is big business, and the Forestry Commission is committed to helping to build suitable venues across the country.

The decision to abandon the Glenmore trail has been criticised by Fergus Ewing, MSP for Inverness East, Nairn and Lochaber. "The idea that all the benefits should be lost simply because of a single caper is outrageous," he said. "It is time we protected the rights of the human species for a change."

Charlton Clark of the Forestry Commission said there was no reduction in commitment to establish a specialist mountain bike trail in the Cairngorms National Park."We are still determined to establish a course which the mountain biking people would take to rather than just a cycle trail which families would go on for a day out. A lot of our forests in the Cairngorms area have environmental sensitivities and high conservation value for species such as the capercaillie so we have to be careful where we site these things. We are now looking at a site 20 miles away at Laggan in the Achduchil Forest."

The commission has five specialist mountain bike trails in Scotland and three more in development.