Dawn blooms and stirs the trees of Abernethy Forest into life. This far north, winter still battles spring for the primeval ground. Mist hangs between incalculable ranks of pines; silver light spills and glimmers over a deep carpet of green moss, russet blaeberry and frost-tipped ling. A waist-high ants' nest bubbles from the ground. From the corner of my eye, a pine bough appears to ripple as a red squirrel skitters along. Then the birds strike up: coal tits, a greenfinch and, from somewhere imperceptible in the thin fog, the cork-popping aria of a male capercaillie.
It's the sound I have come to hear. And I have come a long way. I stepped off the train only a few miles away in Aviemore, but to walk into the largest tract of wild Caledonian Forest is to make a greater journey. After the last Ice Age, this type of pine and birch covered our island before climate and humans forced a retreat north. Now managed by the RSPB, Abernethy's 4,000 hectares remain a thin window into ancient Britain.
To hear a capercaillie, the UK's largest and shyest black grouse, is lucky. To see one is almost impossible. By the time I've heavy-footed through the undergrowth, only a mound of the animal's dinner from last night remains. But "spoor" is not to be sniffed at and, like some scatological Sherlock Holmes, I am on the scent of this wood's other inhabitants. Twisted black pine marten poo is everywhere, fox and red deer droppings too. "There are otters on the loch," a mountain biker shouts, making me jump. I follow directions to tranquil Loch Garten and brew up soup. The air clears and the brooding, snow-capped Cairngorms are reflected in it. There are no V-shaped wakes of otters razoring the water, but an inquisitive crested tit hops about above. There is total, serene, spirit-calming silence. Soon ospreys will be back from Africa to nest and fish here. After being hunted to extinction in the British Isles in the 19th century, they picked this spot to begin a tentative return. Who can blame them?
Abernethy Forest (Nethybridge, Inverness-shire, PH25 3EF) is in the heart of the Cairngorms National Park, two miles west of Boat of Garten, abutting Nethy Bridge to the north. The nearest station, Aviemore, is a 15-minute drive and is on East Coast's direct service from London King's Cross to Inverness. Stay overnight at a delightful Victorian B&B, Moorfield House, at Boat of Garten (01479 831646; moorfieldhouse.com). Doubles start at £78, including breakfast. Book a table at the Boat Hotel, bar and bistro in Boat of Garten for hearty dinners by log fires (01479 831258; boathotel.co.uk).