Miniature worlds on Dundreggan

It was my first day out at Dundreggan for 2 or 3 weeks, and I had planned to go up to look at the new fence that is being erected in the Allt Fearna area, for planting with native trees during the next 3 years. However, the key for the access gate on the hydro road that leads up near that area wasn’t where I had expected it to be, so I ended up spending the time on the low ground instead, not far from Dundreggan Lodge.  

It was what we call a dreich day – grey, overcast and rather damp, although it didn’t actually rain very much – and it was a perfect day for lichens, which swell up with the moisture and look at their most vibrant in these conditions. This drew me to some oaks near the lodge, which have large amounts of lichens on their branches. During the summer the lichens are not very visible as the oaks’ leaves cover most of them up, but now that the leaves are off the trees, the lichens are quite spectacular on days like this.

The profusion of lichens on the branches is an indication both of the clear, unpolluted air here, and the relatively high amounts of moisture in the atmosphere, which enables such a large quantity of lichens to flourish. Many of the twigs and smaller branches are invisible, being completely enveloped in a dense covering of lichens, including oakmoss lichen (Evernia prunastri) and beard lichen (Usnea filipendula).

Some hazel trees growing beside the oaks were similarly bedecked with a luxuriant growth of the same lichen species. Lichens like this are epiphytic, meaning that they use the tree’s branches for support, but don’t take anything from the tree or feed on it in any way. Instead, they gain their nourishment from the rain and humidity in the air, and from particles of organic matter that get deposited on them by the wind.

While I was looking at the oaks and their cargo of lichens, I saw some fallen oak leaves on the ground that still had some colour in them. Most of the leaves were already completely brown, but a few still had some yellow or green patches, and on one those I noticed a couple of small bright yellow-green insects. Looking at them through my hand lens confirmed that they were aphids, and I was quite excited by this, not only because it seemed very late in the season for aphids to still be visible, but also because just the previous day I had received confirmation from someone who is very experienced in identifying aphids that he will do an aphid survey for us on Dundreggan next year.

He said he’s also happy to look at specimens now, so I collected one or two individuals to send to him, and he’s identified them as being Tuberculatus annulatus. As I looked around, I found that there were actually aphids on quite a lot of the fallen oak leaves. We don’t have any records for aphids on oak from Dundreggan yet, so these are a new species to add to the list of biodiversity found on the estate.

The aphids seemed dwarfed in some cases by the raindrops on the oak leaves, and a few of them had water around parts of their bodies. One that I came across was completely contained within one of the raindrops – it was literally inside a little liquid world of its own. Aphids are a group of insects that I’m fascinated by, partly because they have a complex life cycle, with several different stages, in one of which they reproduce asexually, with the females giving birth to live young without mating with any males.

While I was looking at the fallen oak leaves for more aphids, I found one leaf with a distinctive mine in it. This is the work of a micro-moth (Stigmella sp.) whose egg would have hatched at the narrow, pointed end of the mine. The larva then fed in the leaf, moving forward as it grew, so that the mine became wider as it developed. The black material visible in the mine is the frass, or excrement, left behind by the larva as it feeds. When the larva is fully grown it pupates and the adult moth flies off to mate, after which the female will lay her eggs on other oak leaves, and so the cycle continues. Many species of micro-moths make mines in leaves, and I’m hoping we can get a survey of them done next year at Dundreggan as well.

Occasionally, I saw some fallen pieces of lichen amongst the leaves on the ground. The bifurcating, fractal-like shape of the oakmoss lichen (Evernia prunastri) in particular provided some interesting and aesthetically pleasing juxtapositions of colour and form against the brown lobed oak leaves. When the leaves are off the trees, arboreal foliose lichens like this are more vulnerable to stormy or windy weather, and are regularly pruned by the elements during winter.

On several leaves I saw some other tiny insects which looked quite different to the aphids. These moved more quickly and also jumped when I got my fingers too close to them, which made it quite hard to take any photographs. I spent quite a while with several different ones, and in looking closely at them, they looked almost like an alien life form from a science fiction film.

There were some of them that seemed more developed than others, being slightly larger and having more complex colouration to them. I haven’t seen anything like these before, and after consultation with some specialists I’ve discovered that they are a species of springtail (Dicyrtomina ornata).

As I looked at them, I continued to be surprised at how much insect life there still was at this late time of the year, when I would have expected virtually everything to have disappeared for the winter. In fact, almost every fallen leaf that I looked at had something living on it.

On another leaf I saw a worm of some sort – it was an off-white colour and had a series of black blotches visible within its body. It was semi-transparent, so it was hard to get a clear picture of it as its body looked like it wasn’t in sharp focus. The worm moved along the central vein of the leaf, and I surmised it was doing so to be less visible to potential predators, or indeed photographers like me!

By this time I had only progressed about 100 metres from Dundreggan Lodge. It was another day where I had spent a lot of time in a small area, finding plenty of interesting subjects there. It was still grey and overcast, but the rain had held off for most of the time. The light was beginning fade though, so I took a quick walk through the woodland below Binnilidh Bheag, before heading for home again, well satisfied with the miniature worlds I’d found amongst the fallen leaves on Dundreggan.