Thompson Common guided walk, 14 August 2021

This was a joint event between Honeyguide and RSPB Norwich Local Group. This report is by Doug Arkell.

Including Chris Durdin and myself, a party of sixteen assembled for what was, for most of us, a first visit to Thompson Common. Although signage was poor, we all managed to find the car park and arrive in good time. 

Thompson is the ‘local patch’ of recently joined member Phil Childs. He has known the reserve for many years and was good enough to offer to show us around. Luckily there were also several butterfly and dragonfly experts in the party, as the visit was heavily weighted towards those taxa.

Dusky sallow moth on black knapweed.

Our first sighting came in the car park with a white admiral butterfly briefly descending and settling on one of the cars. We joined the path onto the common through a mature wooded area. The brambles were in flower and attracting butterflies including peacock, red admiral, speckled wood and two very tatty silver-washed fritillaries. High in an ash tree several purple hairstreaks were spotted. Though difficult to find among the foliage, Chris Durdin managed to line one up in the scope for us.  A dusky sallow moth was photographed on a knapweed flower.

The path through the reserve forms part of the ‘Pingo Trail’ and we soon came upon some of these features. Forming round depressions with raised edges they provide an aquatic habitat for many species of plants and animals. They appeared to vary in both diameter, depth and in their vegetation. Phil gave us a brief explanation of their glacial origins. As we progressed along the path we came across a small herd of longhorn cattle, which included several cows with calves and a large though very passive bull. These animals, along with Konik ponies, which we did not see, are used to graze the common to maintain the open habitat.

Ruddy darter (left) and common darter (right) [Stephen Spouncer].

From the time we first left the car park we began to see different Odonata (dragonfly and damselfly) species. A few of these insects were attracted to some members of our party and settled on shoulders, hats and hands providing photo opportunities. Male ruddy darter and female common darter on Chris’s hand and Tessa’s hat respectively made an excellent shot. Further along the track we were surprised to see a female southern hawker dragonfly laying eggs directly into a fallen log several metres from the nearest water. Common darters were also seen releasing eggs well away from standing water. It would be interesting to discover the reasons for these behaviours and to find out whether the eggs had any chance of hatching.

Southern hawker egg-laying.

Willow emerald and scarce emerald damselflies are among the several species to have colonised or re-colonised Norfolk over the last 30 years or so. We were lucky enough to see both of these. An example of the former was spotted resting on a dead ash twig a couple of metres above us. There were scores of examples of the ‘scarce’ (not so scarce here) including many laying females and mating pairs. Common blue damselflies, brown hawkers and emperor dragonflies were also prolific.

Pair of scarce emerald damselflies (Doug Arkell).

On our way back to the car park for lunch, we saw brimstone butterflies and Regine disturbed a probable pool frog, a specialty of Thompson.

After lunch myself, Ally, and Chris Durdin followed Phil Childs by car to the other side of the reserve and Thompson Water. Phil explained something of its origins as a man-made feature and more about NWT’s management of recently acquired additional land. There were mute swans, mallards, coots and an immature great crested grebe on the water and we heard chiffchaff, wren and long-tailed tit in the bushes near the banks. Red-eyed damselflies rested on duckweed in the shallows.

Looking at the reserve plan it was obvious that the group had only covered small part of Thompson, so there is much more to see here. More photos here.

Doug Arkell