Our invertebrate man at Portmoak Moss
George Guthrie is a volunteer at Portmoak Moss in Fife, near Loch Leven, and has written us a piece about his experiences and findings there. For many years he has been recording invertebrates at the site, passing the records on to the Site Manager to help inform management prescriptions for the site. George has an incredibly high level of expertise and we are incredibly lucky that he commits so much time into helping us to understand the complex ecology at Portmoak. The woodland consists mainly of mature conifer plantation, along with some mixed woodland and native broadleaved woodland. At the core of the site is a large open area of raised bog habitat (an area of deep peat), one of few remaining in central Scotland. As a result the wood is a refuge for a variety of wildlife including red squirrels.
I met George on site earlier this year so he could talk me through some of what he does. Here’s some photos of him with some fox moth caterpillars that he showed me on the day!
So, it’s over to George:
As I was brought up in this area I can remember Portmoak Moss in the 1950s as a heath with very few trees, and it was grazed heavily by sheep at that time. From the early 1960s I moved away to stay and work in Glen Isla in North East Perthshire then in the mid 1970s I moved back to this area again and on visiting Portmoak was astonished to find it was now a forest! Then through the 1980s and 90s I was working all over Scotland and parts of England so had very few visits to Portmoak.
Then in 2006 I retired so had a lot more time to do the things I liked to do such as looking for insects (as you can tell I’m a bug hunter), so from then on there was a lot more visits to Portmoak. The Dragonflies are of particular interest to me. There are four species at Portmoak; early in the season there are Four Spotted Chasers, a little later there are Common Darters, later still come Black Darters and then towards August the Common Hawkers are on the wing. There are also four species of damselfly. In May there are Large Red Damsels, by June there are Azure Damsels and Blue-tailed Damsels and then by August there are Emerald Damselflies on the wing.
There are 15 Butterfly Species on the Moss, the rarest are the Small Pearl-bordered Fritillary, closely followed by The Green Hairstreak. These tiny, green butterflies have a very interesting life history – they hatch in late April / early May and feed on Blaeberry nectar. Then they mate, lay their eggs on various plants, and when the eggs hatch the caterpillars feed on these plants for a short time. Then, when still very small, about 2mm or so, they make their way onto ant trails and “cry” to the ants and somehow convince the ants that they are lost ant larvae. Then the ants pick them up and take them down into their nest, and the little caterpillars become carnivorous, eating the eggs and larvae of the ants! Why the ants allow this is not known although it is known that ants get a little honeydew from them; this is a by-product of the caterpillar. They continue feeding in the ant’s nest all summer and then by October / November they pupate and spend the winter in the comfort of the ants’ nest. The pupae are about 16/19mm so they must be like an elephant in a sheep pen by this time. By late April they emerge from the ants’ nest to start the process all over again.
There are 7 species of Bumblebees on the Moss. The rarest is The Mountain Bumblebee (Bombus Monticola), that feeds on blaeberry and the various heathers that grow on the Moss.
The Moths are many and varied and I have recorded over 230 species on the Moss. Some are very rare like the Wood Tiger….. no! no! not a big cat but a moth. a The Emperor Moth is also there; it is a real moss specialist. I survey the Moss weekly for butterflies and bumblebees from the first week in April until the last week in September. The dragonflies we start surveying from May onwards and the Moths are surveyed monthly from March till October.
Thanks to George for these beautiful photos and fascinating insight into the world of insects at Portmoak!