Four-fifths of the UK's dwindling population of capercaillie live in the national park, but experts have said the birds are suffering because of escalating interference from residents and visitors.
According to Dr Robert Moss, a wildlife biologist who has made a lifelong study of capercaillie, the national park is "conflicted" on the issue and ignores the advice of its own ecologists.
He is the lead author of a new scientific study of three woodlands in the Cairngorms area showing that capercaillie are very vulnerable to human disturbance.
The birds stayed hundreds of metres away from places where people entered woodlands. The study was published in the journal Wildlife Biology. Capercaillie populations have declined from 20,000 in the 1970s to fewer than 2000 now.
The national park's chief executive, Grant Moir, pointed out that the park was developing a management framework for capercaillie to address the issues highlighted by Mr Moss.
Mr Moir said capercaillie were "one of the big ongoing challenges in managing the park," adding "Dr Moss's work is already informing the way we are tackling this through habitat enhancement and managing the impact of human disturbance."