Its distinctive silhouette first appeared over the brow of Sgulan Beag. The golden eagle, its wing feathers elegantly curving upwards, drifted sedately high over the glen; its eyes trained intently on the rough moorland below. Then a second eagle appeared; the pair circled in a slow waltz, coasting on the air currents.
"The bigger one is the female," said Dave Sexton, the local Royal Society for the Protection of Birds officer as he tracked them through his binoculars. "The other one is an immature bird - they've gone off into the mist. Now it's slightly drifting this way."
Sexton was standing next to the single-track road that twists alongside Glen More, one of several prime territories for eagle watching on the Hebridean island of Mull - an area rated as one of the best areas in Europe for the species.
Along the glen, a thin line of birdwatchers had their binoculars and expensive single-eyepiece scopes trained at the sky, slowly tracing the birds' leisurely path westward towards the coast and the island of Iona. One visitor from Suffolk had just come off the Oban ferry and had quickly seen a pair of sea eagles and two hen harriers - a species severely threatened in England.
Within a few minutes, dramatic scenes. Another golden eagle had appeared over Sgulan Beag, looping and diving in a territorial display, its wings swept back as its plunged down and then pulled up, once, then twice. As it did so, the small form of a kestrel came into sight - moving directly at the eagle. "Look! That kestrel is coming in quite fast," exclaimed Sexton. "It's hit him on the back. He's mobbing him, trying to get the eagle to move on."
The kestrel must have had a nest close by, he speculated. The eagle seemed unfazed. It, too drifted westwards, and the kestrel abandoned its attack. Within that 30-minute burst of activity, several sea eagles and an energetic, darting sparrowhawk had also flown past - proof of Mull's status among wildlife watchers.
Eco-tourism is a relatively new phenomenon on Mull, but its status as a centre for wildlife watching is well deserved. The island and the string of smaller islands, leading through the inner Hebrides north to Skye, have the highest concentration of golden eagles in Europe, possibly the world, says Sexton.
There are 20 breeding pairs on Mull, earning the island special protection area status - one of the highest European nature conservation designations - for its golden eagle populations, while roughly 20 more are breeding on Skye. Combined with marine wildlife safaris for whales, otters, dolphins and seals, and trips out to the strikingly beautiful outlying islands of Coll, Iona, Tirree and Staffa, a thriving ecotourism industry has sprung up. Several companies specialise in eagle watching. Ranger-led tours are organised by the Forestry Commission to a plush hide near Loch Frisa, where CCTV is trained on a sea eagle nest - a service known locally as ChickTV.
Within Britain, golden eagles are confined almost entirely to Scotland, a consequence of historic loss of habitat and continuing persecution by gamekeepers and farmers. The only golden eagle in England is a solitary male living in the Lake District, which last bred 10 years ago.
Last month, the RSPB said the species ought to be common in northern England's uplands and the Welsh mountains, but it had been unable to colonise from Scotland because of persecution on both sides of the English border.
There are thought to be 400 breeding pairs across Scotland, particularly the western and northern Highlands. Its population has remained constant and its popularity growing. Its iconic status as the country's unofficial national bird has been underlined by Scotland's devolved government and, on Mull in particular, that status is vigorously protected by islanders.
In 2000, islanders and Strathclyde police set up a unique "neighbourhood watch" scheme for its eagles after a spate of egg thefts at sea eagle nests. The bird is slowly recolonising Scotland after two reintroduction programmes. Around 40 volunteers, often supplemented by police officers on leave from the mainland, run Mull Eagle Watch, using hidden CCTV cameras and surveillance to watch the most vulnerable of the 10 breeding sea eagles' nests and other vulnerable golden eagle nests. Egg thieves and photographers are arrested and prosecuted, and the exact location of eagle nests are a closely guarded secret.
Wings over Mull, a bird of prey sanctuary and hospital near the main ferry terminal for Oban, offers an even gentler bird watching experience - particularly for children and the less well-equipped and knowledgeable. While better known for more than 40 owls, hawks, falcons, vultures and red kites, the conservation centre is caring for two wild golden eagles - a 25-year-old female that had been blinded, and a young male with an irreparably broken wing, rescued by islanders. And both happily pose for close-ups.