Mostly, the tourists who pause here are still acclimatising to the Highlands, which began six uncompromising miles to the south. It is a heady enough brew - a good tight pass, clamorous waterfalls, loch-hugging mountains, forests and deluges of midges - even without swans.
The unaccustomed eye, pausing Thermos in hand, will invest the swans with qualities of serenity, grace, poise, an ornament of nature set in this landscape almost unnecessarily, like an extravagant jewel in the navel of an exquisite belly dancer.
But mine is an accustomed eye when it comes to swans, and that pair of mutes in particular. Even by the standards of swans - few tribes of nature are credited and hamstrung with more superlatives - these are extraordinary birds. Tourism, if it considers them at all, might find them curiously aloof. They do not home in on the tossed left-over crumbs of the B & B's packed lunch. If anything, they drift further out into the deeper water darkly shadowed by the mountains.
There are two reasons for such behaviour. One is the nature of their environment. The wildness has infected them so that they behave more like the whooper swans of Iceland than most people's perception of mutes in Britain.
The other reason is that their whole year has just been robbed of purpose. It was a small tragedy by nature's standards, a death which removed from the surface of the loch and my own wild year the small grey apostrophe of the last cygnet. The birds, if they are not mourning (and who really knows who is not a swan?) are certainly moping. Their year has been a measured, stoic struggle. It always is, such are the forces of nature which habitually conspire to thwart their life cycle.
In the past five years these birds have built 19 nests and raised only eight cygnets to fledgling. Yet even in the worst of the Highland winter they rarely leave their home water for more than a few days, if at all. Whatever it is that keeps them here, whatever it was that first lured swans here (20 years ago at least to my certain knowledge, possibly much longer), it was not the prospect of an idyllic lifestyle.
It is hard to ignore the possibility that here are the descendants of a long line of mountain swans, accustomed to, and possibly dependent on the uncompromising natural regime, in the same way that an Icelandic whooper is.
This year's saga is typical. It began, as always, with the floods.
At the end of every winter the river which feeds the north end of the loch swells with the rains and the snow-melt of a dozen mountains. The loch's level rises. Three or four feet in a day is common in the worst weather, and the swans swim between tree tops and over fences. Land on which they might choose to build a nest is obliterated. So for that matter is anything to build it with. So they wait, and - while their lowland kin on a farmyard pond not 40 miles away have courted, built, mated and laid - they go on waiting.
By late April, by which time the lowland mutes are perhaps a week from hatching, the Highland rains have eased, a scrap of land by the riverbank has emerged, the swans have scraped together a pile of grass.
The pen climbs aboard and sits. She has begun to lay, but the floods fall as fast as they rose. The attempt is doomed. Two days later she walks away from two eggs, and the nest is now quarter of a mile from the water's edge. The process is repeated on a second nest with the same result, except that this time she laid three eggs. When she abandoned a third nest and two more eggs, a bit of human intervention seemed worth a try. It was time to bring the raft into play.
'Raft' is grand flattery for the hastily cobbled together floating platform which a lochside local and I had first boated out into the edge of a reed-bed last year to try and entice the swans on to a flood-proof nest site.
Then their third nest was washed out of the reed-bed and on to the shore by late floods; they finally reared two young after the nest had been manhandled back to the raft and tied on to it.
So, as one more nesting season disaster threatened, the remains of this year's second nest were hauled aboard the raft, along with the two eggs the pen had abandoned. By mid-June she had hatched them both, and left one more infertile egg in the nest, which she and her mate had rebuilt on the raft.
But mid-June is too late for optimism among new-born cygnets and swan-watchers. Statistically, late hatches fare poorly. The first cygnet died within two weeks, unseen by anyone. Gone without trace, but it had never worn that sheen of robust health I had seen on the lowland brood - all seven of them tumbled from their small island nest on a farmyard pond in the first week of May.
Now the second Loch Lubnaig cygnet has gone, and the adults mope away the leisurely days of late summer, but still they show no inclination to seek out easier climes.
Instead they demonstrate limitless powers of patience, endurance and resilience in the face of such consistent adversity and loss. In the process they have made gibberish out of field guide statistics. These intone for example that eggs hatch after 35 days (and sure enough in ideal conditions they often do), but they are silent on how an extreme perversity of nature might affect matters. In my own book, Waters of the Wild Swan, I recorded the climax of one particularly odd nesting season: 'On the next day, the forty-first on her third nest, June 25, I sat by the dyke at noon, put the glasses on the nest, watched her stand, and there at her foot saw a single stumbling gray fluffball, complete with black bill, black eyes and black feet. The pen had laid her first egg on her first nest on April 15. Now, two nests, an unknown number of eggs and seventy-one days later, she had one cygnet . . .' It was enough for her, and she took to the water at once with the cygnet. The cob, however, sat on four more eggs for 10 days more, taking the total to 81, before abandoning them. It was October of that year before I found the pyre of grey feathers which denoted the cygnet's death, killed or scavenged by a fox. As well, perhaps, that the cygnet died on a glorious autumn day rather than suffer wretchedly through the long, cold and wet Highland winter. It is not a season for nature's weaklings.
So now my Highland swans are cygnet-less again, but a mile down the loch is a swimming symbol of hope. Two young mute swans, slim and pale-beaked, keep each other company and grow strong through the late summer. They are last year's young, and they have never left their home water; no instinct has urged them south to join lowland swans on gentler waters.
They are brother and sister, living just beyond their parents' territory. Assuming there is another suitable site on the loch (there are several, and heaven knows how many unsuitable ones) might they eventually mate, or - separately or together - take over their parents' site and spend their entire life here? They are isolated from other swan populations, pure-bred mountain swans, and as unconfiding in people as their parents.
Last year, when they were growing up with their parents, all four birds would come to a call and take food from me. Now, though, the same call produces no response from the young birds. That's good.
They will need all the resources of wildness they can muster if they are to lay claim in time to their grim inheritance.
Jim Crumley is the author of 'Waters of the Wild Swan' (Cape, pounds 14.99) and will feature in a BBC 1 film in November, 'Addicted to Swans'.