Two winter visits to the Traligill Caves

May 8th 2018

Some 3km up the valley of the River Traligill, east-south-east of Inchnadamph, there is a prominent small hill called Cnoc nan Uamh (rounded hill of the caves).  On its north-western flank lies the close group of three caves from which it gets its name (NC276205).  This was our destination on 6th January; a ‘pipe opener’ for 2018.

All the surrounding hills were white over; the only other person we met all day had been forced off an ascent of Conival by waist-deep snow. The sky looked threatening, but further precipitation held off, thankfully.

After a coffee stop by the isolated cottage at Glenbain, we made a small diversion to admire the impressively large sink-hole at NC270208, where the Traligill disappears underground for half a kilometre (photo 1). Nearby, Gwen spotted a large piece of rotten wood, probably part of a dead branch from an oldrowanon the crag above the sink-hole.

This gave us our first observations of the day, other than the solitary raventhat had crossed our path high overhead.  The wood was stained with the unmistakeable copper-green signs of rot by the fungus green elfcup Chlorociboria aeruginascens(photo 2), but there were also some small, black, lobed fungal fruiting bodies that we did not recognise (photo 3) – unsurprisingly, since the British Isles house some 12,000 species of fungi.  A specimen was later identified by Bruce Ing as the ascomycete Rhizodiscina lignycola; it is supposedly uncommon in the north-west, but had been previously recorded in Assynt by John Blunt, albeit not so far inland.

Reaching the caves, we ate our lunch in a sheltered spot by the lower caves, looking down the valley to a snow-topped Quinag (photo 4) and then climbed up to the uppermost of the three, which is a deep pothole with the river roaring through out of sight far below (photo 5).  Its steep-sided walls, protected both from the elements and grazing, are covered with ferns, including handsome clumps of two related species, hard shield- fern Polystichum aculeatum and holly fern P. lonchitis (photo 6).  The former is widespread in sheltered sites in Assynt on base-rich rocks, including some facies of both the Torridonian and gneiss; the latter is much more restricted, mainly to outcrops of limestone and the Fucoid Beds.  After taking a number of photographs, we made our way back down the valley (photo 7), picking up just two further species of birds, just before reaching the road, a great tit with a convincing, if early, call of ‘teacher…teacher’ and a dipper bobbing on a rock in the middle of the Traligill.

Reviewing our photographs later, enlarged on the computer, it occurred to us that this site was possible for the hybrid between the two species mentioned, the very rare Polystichumx illyricum, the first Scottish record of which was made in 1973 by Alan Stirling in boulder scree below the cliffs of Creag Sron Chrubaidh.  It also occurs, with both parents, in a large deer-exclosure just over a kilometre to the south-west of the Traligill caves.

So, we mounted a second expedition to the site on 2ndFebruary, to take a closer look at the ferns.  Rain threatened, with a rainbow in the west, but the sky over Inchnadamph cleared and brightened, allowing us to take further photographs (photo 8), including one of a bush of whortle-leaved willowSalix myrsinites hanging over the mouth of the upper cave (photo 9), which Alex Scott had told us about.  This species, which has shiny leaves and striking purplish male catkins later in the year, is almost entirely restricted to the limestone, where it is, regrettably, grazed hard by red deer; there is an interesting outlier on the Torridonian at the foot of Beinn Gharbh, across Loch Assynt.

The jury is still out on the presence of the hybrid, since it can be difficult to distinguish from its hard shield-fern  parent and the second set of photographs was not decisive. We are agreed, regretfully but definitely, that it will take more agile botanists than us, properly roped, to get close enough to the fern clumps on the vertical, slippery, walls of this dangerous site to be certain.

Having done what we could at the caves, we made our way over to a dry valley running parallel to the Traligill on its south-west, to see what we could find there.  At the head of this valley moschatel Adoxa moschatellinawas discovered by Robin Noble in May 2008; a new locality, the only previous record being from Knockan Crags, back in 1894.  Our first find was less exciting, but interesting nevertheless, the carcase of a red deerhind, stripped to skin and bones, with evidence of one of the beneficiaries, a nearby fox scat (one of several spotted that day).

Further down, bothhard shield-fern andhollyfernoccurred on a low crag on the valley side, inaccessible, but near enough for us to see that there was no suspicion of the hybrid.

Working round a step in the valley, which houses a small waterfall on occasion, we found a good stand of holly fernon the southern wall, in a place that we could reach but which the deer had spared (photo 10).  It is so attractive to the burgeoning red deer population of this area that all extant sites are in potholes, high on rock faces or in extensive boulder scree.  It was accompanied by green spleenwortAsplenium viride, a very good indicator of base-rich sites, which is rather more widespread in Assynt.

Nearby, we came across two of the characteristic lichensof limestone areas, the green dog-lichen Peltigera leucophlebia, which has dark outgrowths of the cyanobacterial photobiont on the thalli (photo 11), and another bright-green lichen, Solorina saccata, with enormous cup-shaped apothecia (photo 12).  Finally, on a trackside limestone boulder not far above Glenbain, there was a striking black-and-white crustose lichen, later named by Tony Fletcher as Porpidia speirea(photo 13).

Birds, as ever in the interior of Assynt in winter, were sparse, the total tally, at two ends of the size spectrum, being two ravensand a wren.

So, no stunning discoveries, but a reminder of the interest of Assynt limestone country, even in the depths of winter.

Ian Evans and Gwen Richards

 

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