The capercaillie is a native species that became extinct in Britain in the mid-18th Century but were reintroduced in Perthshire in 1837.
Earlier this year the Scottish government announced an emergency plan to boost numbers in the Cairngorms.
Breeding male capercaillies have increased by by 50% since 2020, but numbers had declined as a result of habitat loss, eggs being eaten and the birds flying into deer fences.
A visitor centre which runs guided trips to see free-ranging reindeer in the area said that the animals had been let out onto the mountains, adding “they are not close to the fire and will keep themselves safe”.
Ross Ewing, from Scottish Land and Estates, said the incident was “clearly serious and fast-moving” and urged members of the public to keep routes clear for emergency vehicles.
He also encouraged landowners and land managers to take precautionary measures including the readying of specialist fire equipment.
Staff at Glenmore Outdoor Centre, which is near the blaze, asked people not to travel to the area.
They said: “Follow official advice from Scottish Fire and Rescue Service, and be patient with staff while the ongoing situation is managed appropriately.”
A spokesperson for the Cairngorms National Park Authority said the fire was “deeply concerning”.
They added: “This incident – alongside wildfires we are seeing across the UK this week – serves as a stark reminder of the risks that periods of drier, hotter weather can pose.”