Imagine the comical mating ritual of the capercaillie bird, the flash of a red squirrel sprinting by and the grunt of a reindeer -- all set against the backdrop of an ancient Caledonian forest, remnants of a landscape that once covered the British Isles.* Related article: Mini guide to Aberdeen, ScotlandCairngorms National Park is nearly 4,500 sqkm of mountain wilderness in northeastern Scotland and is the country’s largest protected area. The diversity of its fauna and flora is often overlooked due to its renowned status as Britain’s top ski destination. But its isolated location, far from any big cities, means that the Cairngorms are less visited than most other national parks in Britain. A mere 1.5 million visitors (as opposed to the Lake District’s 15.8 million) make the journey each year.Arctic voyage From the park’s main town, the ski centre of Aviemore, valleys of lofty pine trees and pristine lochs cut dramatically into corrie-riven mountains and the United Kingdom’s most extensive plateau. This granite massif retains the characteristics of an arctic-alpine tundra ecosystem, where high-altitude forest and wild, rocky plains combine with cold winds and low temperatures to provide a habitat found nowhere else in Britain. This remoteness has allowed rare animal, bird and plant species to thrive, and its mountains are among the world’s last sanctuaries for many Arctic birds and plants outside of the Arctic Circle.Walk on the wild side The Cairngorms is famed for two creatures: the osprey, which nests on a reserve after declining to near-extinction in Britain during the 20th Century, and the United Kingdom’s only herd of reindeer, which ranges free in the Reindeer Park above Aviemore. The Royal Society for the Protection of Birds runs guided walks around the Loch Garten reserve north of Aviemore between April and August to see ospreys and other seasonal incumbents such as siskins, crossbills, sandpipers and otters. Ask at the Reindeer Park about joining the herder and leading your own reindeer on a half-day trek to their mountain enclosure (possible between June and August only).The Rothiemurchus Estate, one and a half miles from Aviemore Railway Station, provides a host of family-friendly safaris themed around the distinctive, shaggy ginger Highland “coos” (cows), red squirrels and red deer. Meanwhile, nearby Atholl Estates whisks you off by Land Rover on safaris which take in various birds of prey, mountain hares and deer, in stunning forest and moorland terrain. If you are looking for more than just wildlife-watching, Alvie Estates offers a glimpse into life on the other side of the fence: human management of the land and its potential conflicts.High-altitude wildlife The hikers and climbers that make it to the most remote Cairngorm forest and plateau can expect to see even rarer species.The Scottish crossbill, Britain’s only endemic bird, has the park’s pine trees as its sole stomping ground. The capercaillie, a large, colourful bird with one of the natural world’s most entertaining courtship displays, uses these forests as one of its last European breeding grounds. Wildcats and pine martens also roam. Higher up on the plateau, Arctic buntings, ptarmigan and golden eagles can be glimpsed, while the mountain scrub is adorned with rare plants such as globeflower and roseroot.Recently, the reintroduction of once-native species to Scotland (such as elk, boar and wolves) caused fierce controversy at the Highland estate of Alladale, an idea that could seem laughable to the locals around Cairngorms National Park. With so much prestigious, flourishing wildlife of its own, it is ironic that the national park does not get more international attention. But the laughter ricocheting through the valley is far more likely to be the capercaillie, attracting its mate. Listen out: it will sound like a quickening drum beat followed by a bottle of champagne being uncorked and poured. It is a one-of-a-kind experience, to be sure.