Spring delight in Strathfarrar

Spring seemed to have finally arrived in the Highlands at the end of the first week in April, when I made my first visit to Glen Strathfarrar for several months. On the previous Sunday, the last one in March, when I’d been out in the western Highlands I’d experienced driving snow, sleet and hail all day, with the temperature never rising about 2 degrees C. all day long, and it had felt like the middle of winter still.

By contrast, this was a beautiful sunny day, with cloudless skies in the morning and very little wind throughout the day – a complete contrast to the previous week-end. As we were also past the spring equinox, there was more daylight than darkness each day and the quality of the light had changed too, with the sun being much higher in the sky again. This day in particular the light seemed to glow in the needles of the Scots pines (Pinus sylvestris), making the trees appear particularly radiant and full of life.

As I drove up the glen I stopped at a place where there are some pines growing on rock outcrops on the north side, and noticed some aspens (Populus tremula) there that I hadn’t been aware of before. One tree in particular was growing right next to a birch (Betula pubescens), and it was easy to tell them apart by the different patterns of growth of their branches. My colleague Jill Hodge had recently run a day-long course at Dundreggan to help people identify aspens when they are leafless like this, to keep an eye out for when they are flowering, and had asked me for some photos that show the difference between aspen and birch when they have no leaves. Although I’d already passed some photos on to her, I took some more this day as well, as the variation between the two species was quite clear here.

 

 

 

 

 

 

 

The place where these pines were growing was typical of many of the old forest remnants. They had been able to grow successfully on the rocky outcrops because they would have been out of reach of red deer (Cervus elaphus) there when they were young.

 

 

 

 

 

 

 

One of my favourite phenomena in the forest at this time of the year is the intensifying colour of the birches, as their buds swell, ready for the new leaves to emerge. They turn a deeper reddish-purple just before leaf burst occurs, and the colour this day made a nice contrast with the bright green of the Scots pines’ foliage.

 

 

 

 

 

 

In the bright sunshine the absorption of the sun’s energy by the needles of the pines was almost palpable, and I had the feeling that the warmth and radiance of the day was calling the birches to open their buds and release their leaves for a new season of growth.

Just beside the road, my eye was drawn by a dense, low green bush, and when I looked closely I saw that it was a heavily-overgrazed holly (Ilex aquifolium).

 

 

 

 

 

 

 

This young holly had had its leader shoot eaten back repeatedly by the deer, forcing it to grow in a dense, concentrated form which some people have likened to topiary – the human practice of pruning or cropping trees and shrubs into unnatural, ornamental shapes. I’m always surprised that holly gets overgrazed like this – the deer seem to relish it, despite the prickliness of its leaves. I don’t know of many holly trees in Strathfarrar, so it was sad to see this one so completely suppressed and held in check like this by the grazing pressure.

Driving a little further into the glen, I parked my car and prepared to walk in the forest. My route would take me across a bridge over the Farrar River and up into the larger area of native pinewoods on the south side of the glen. However, no sooner had I crossed the bridge than I spotted a couple of green tiger beetles (Cicindela campestris).

 

 

 

 

 

 

 

This is one of our most spectacular and unmistakeable beetle species, and, as is often the case, I saw these individuals right on the path itself. It’s a predatory beetle, and I followed these two for a while as they alternated between rapidly crawling across the ground and flying for a few feet at a time. Because of their rapid movements I had to use the flash on my camera to get any photos, to freeze their motion.

After a while, when I’d taken a few images, I decided to have a close look at a Scots pine that is right beside the path there. It’s one of my favourite pines in Strathfarrar, and has multiple trunks and a visible root system, where flood waters from the river must have washed the soil away around it. I’ve photographed it on various occasions over the years, and one of those images featured on the back cover of the Trees for Life Engagement Diary some years ago.

 

 

 

 

 

 

 

Because I had the macro lens and flash on my camera, I was hoping I might see (and photograph) some wood ants (Formica sp.) on the trunk of the pine, as they would certainly be active on a warm sunny day like this.

When I looked at the tree though, there wasn’t any sign of wood ants on it, but my eye was caught by some movement on the bark, and as I looked closer I saw that it was a spider, and one that I recognised as well – the lichen running spider (Philodromus margaritatus). This is a superbly camouflaged species, and blends in perfectly with the lichens that were growing on the trunk, as can be seen in this photograph to the right.

In fact, the only reason I saw the spider was because it was moving, and when it crossed from a lichen patch on to the bark of the Scots pine, it became much more visible. This spider is a priority species for conservation under the UK’s Biodiversity Action Plan, and I’ve previously seen (and photographed) it both in Glen Affric and on Dundreggan. Not surprisingly, it seems to favour older trees, which have well-developed lichen communities on them, so that its camouflaged coloration can be most effective.

 

 

 

 

 

 

 

When I’ve seen this spider before it’s been on other trees, such as birch, oak (Quercus petraea) and aspen, and this was the first time I’d come across it on a Scots pine.

This particular individual began moving down the trunk of the tree quite quickly, so I was able to get a series of photographs as it descended, with some of them showing the spider clearly against the bark, and others where it was virtually invisible, in amongst the lichen. These were common species of lichens, including heather rags lichen (Hypogymnia physodes) and frilly lettuce lichen (Platismatia glauca), which occur on a range of tree species, so the spider has obviously evolved its coloration to take advantage of their abundance.

According to the British spiders web site this species has a disjunct distribution, with a cluster of records from the Scottish Highlands and others from scattered sites in the south of England, with none in between. This unusual range could be the result of forest loss in much of the UK, with suitable old, lichen-encrusted trees missing from most of the country. The species is apparently widespread in western and central Europe, but is absent from Ireland, which is the country with the lowest percentage of tree cover and old forest remaining on its territory in all of Europe. 

As the spider continued to move down the pine trunk I suddenly spotted another one, sitting motionless on the bark. Although the coloration of this one was slightly different, it was clearly the same species, and a male this time – its gender being indicated by the presence of palps, appendages that look like miniature boxing gloves, and pointing forwards from the front of its head. Surmising that the first one was a female, and some courtship may follow as a result, I took the opportunity, while they were motionless and facing each other, to fetch my tripod from where I’d left it a few feet away, so that I could mount my camera on it and shoot some video footage.

It only took about 20 seconds to return with my tripod , but when I did so I was disappointed to see that the female had moved and was nowhere to be seen. The male was still there though, but he had turned around and was facing down the trunk (perhaps because the female had departed that way?). The courtship and mating I had hoped might take place (and capture on video) was not going to happen now, but I continued to watch, and photograph, the male spider for a while.

He sat motionless on the bark for a few minutes, and then, when I wasn’t looking, must have moved, because when I turned back to the spot where he’d been sitting, he was gone. He hadn’t moved far though, and by searching the adjoining area of the trunk closely, I discovered him, perfectly blending in, against a patch of lichen a few inches away.

 

 

 

 

 

I watched the spider for a few more minutes, but he remained motionless, possibly waiting for some insect prey to pass by, so eventually I moved on, full of gratitude for the privilege of having spent some time with these remarkably camouflaged arachnids. Here’s some video footage I took of the spider:

The path climbs up a hill as it moves away to the south of the Farrar River, and as I ascended, there were some fine views of the Scots pines on the slopes, with the bare shapes of birches in the foreground.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I stopped to look at one old birch along the way, as its bark was encrusted with a bright yellow lichen (Chrysothrix candelaris). I’d photographed another birch tree in Glen Affric with this species on it a few weeks previously, on a snowy day that featured in one of my other recent blogs.

I didn’t have time to go much further though, but before turning back I stopped by one old Scots pine with a distinctive bracket fungus (Phellinus pini) on its trunk.

 

 

 

 

 

 

 

This provided a fitting end to what had turned out to be a delightful spring day in the old forest of Glen Strathfarrar, with the highlight having been my memorable encounter with the lichen running spider – an experience that will stay with me for a long time.