Tuesday, 9 July 2013

Fen Dragons

In the summer doldrums I like to pass the time in getting to know the rich variety of insect life that abounds in our country. Butterflies, moths, dragonflies and damselflies are all of interest to me and (dare I say it) I'm even keeping lists for all of these - it gives one the prospect of a "tick hit" in what would otherwise be a lean time of the year. This also means that one gets to visit lots of different type of habitat and locations in pursuit of these insects. There is one particular type of habitat, namely alkaline fen, which only occurs in one place within the county and this of course attracts it's own particular specialist species including some dragonflies and damselflies that aren't found anywhere else within the county. The Cothill Fen, is apparently the largest surviving area of alkaline fen in central England. It is fed by underground springs from underlying limestone which gives the water it the alkalinity and ensures that the fen remains wet all year round. Fens differ from bogs in that the spring source water runs off so it is constantly flowing whereas a bog consists of accumulated stagnant rain water. In effect a fen is like an extremely shallow marshy stream. Three reserves help to preserve this rare habitat: Dry Sandford Pit, Parsonage Moor and Cothill Fen NR. Given how sunny and hot the weather was, I thought that it was about time that I visited this unique area and caught up with the specialist dragonflies and damselflies that inhabit it. Therefore it was that on swelteringly hot Sunday morning, with Luke (my seven year old son) in tow, I set off for Dry Sandford Pit.
Some interesting info about the habitat and the reserves

The first problem was to locate the pool itself within the nature reserve: Luke and I wandered about a bit without any luck before I decided to give Badger a call. He confessed that on a previous visit he'd never managed to find the pool either but fortunately Peter Law knew where it was and a call to him soon put me straight. A few minutes walk and we were surveying the area of rushes with a thin clear trickle of spring-fed water running through it in what are called runnels if I remember correctly. I wished that I'd brought wellies instead of my walking boots though fortunately Luke was properly equipped. We soon found a couple of Keeled Skimmers and several blue damselflies that turned out to the Southern Damselflies (a specialist for the area), two of the species that I was after.

Of course trying to photograph them was quite a problem as the autofocus struggled to lock on to the insect perched up on the top of a reed but instead kept picking out the background. As the light was so good (so lots of shutter speed to spare) I cranked the F stop right up to increase the depth of field and by locking the focus on things that were the same distance away (often my hand when all else failed) I was able to get some passably in-focus shots with the super-zoom.

Keeled Skimmer

Southern Damselflies

Next it was on to Parsonage Moor which was a much larger and more reedy area though again with runnels running through it and a few boggy pools. By the largest pool there were at least four Broad-bodies Chasers and a couple of Keeled Skimmers. Further round we found several more Keeled, a pair of Large Red Damsels and another Southern Damsel. We also disturbed a small Grass Snake which Luke got very excited about - he had been rather bored on the trip so far and kept asking when we were going home but the snake he found very interesting.

Teneral female Keeled Skimmer
Mating Keeled Skimmers
Large Red Damsels
Southern Damsel - the black pattern on S2 and the two blue stripes between the ocular spots help clinch the ID for males

Finally to Cothill Fen which was a know area for Small Red Damselflies and we soon found quite a few of them in amongst the boggy grass.

Small Red Damsels - unlike Large Reds, these lake the black markings on 
the lower abdomen and the large red antehumeral stripes.

So I'd managed to catch up with all the expected alkaline fen species. However, by now the heat was getting to us so we wandered back to the comfort of the air-conditioned car and headed back home, very pleased with our visit.


JRandSue said...

Stunning collection.

Adam Hartley (Gnome) said...

Thanks John!