Sunday, 3 August 2014

Cothill Fen and Dry Sandford Nature Reserves: a home for rare Oxfordshire dragonflies and damselflies

This morning I had an opportunity to visit the Cothill Fen cluster of nature reserves to the south west of Oxford, all managed by BBOWT.  Though relatively small is size, these sites are remarkably rich in plants and invertebrates and I think are the only place in Oxfordshire to see three species of Odonata (the dragonflies and damselflies) otherwise largely confined to the New Forest and other southern heathlands.  My planning was considerably aided by Stephen Burch's excellent website which contains loads of useful information on these and other sites, the species and up to date sightings info.

The weather pretty much played ball but it was a slow start at Dry Sandford Pit, and I was wondering if there were any dragonflies around at all. Then a common darter appeared and perched beautifully for me.
male common darter

Soon afterwards I spotted the first of my "Big Three", a male keeled skimmer.  The male was sat perched  on marshy vegetation, then took off and patrolled across his small territory of a few square metres, then returned to the exact same spot.  About three metres away another male was doing the same thing.  I took some pics with my 400mm lens.  Noticeable how the wings are held forward when resting.
male keeled skimmer
male keeled skimmer, wings held in forward position
Next up was a blue damselfly that had me chasing around and realising I need to wear my glasses to see the close-up detail these days.  Fortunately the long lens helped confirm identification of southern damselfly - now it was two down, just one to go. 
male southern damselfly
I enjoyed a walk around the rest the Dry Sandford Pit; there is much more besides the dragonflies - patches of dark mullein caught my attention.  Lots to learn about geology too.
dark mullein
A short walk away is another BBOWT reserve, Parsonage Moor.  This is a much more extensive area of fenland, unaffected by quarrying.  The guidebook describes this site as "atmospheric", which it really is. A world away from the villages, towns, traffic and intensive agriculture nearby.  Springs feed lime-rich water into small streams, in turn irrigating a wetland that varies from alkaline to acidic and supports a great variety of wildlife.  I focused attention on one of the small streams next to the stretch of boardwalk.  I soon realised about six keeled skimmers have territories here.  A few more southern damselflies are also flying discreetly through the rushes, including a pair egg-laying.  The much larger brown hawker gives a fly-past too.  A pair of common darters are also getting together.
common darter pair

 I was so absorbed that I forgot about the last of the big three, then it appeared. I took a photo; it disappeared. That was all I saw.  But that was all I needed to confirm a small red damselfly.
small red damselfly - all too brief, but conclusive!
Parsonage Moor - the tiny stream home to the Big Three
These two sites are well worth repeated visits though the season - I also saw grass of Parnassus in bud and the seed heads of marsh helleborine, two extremely rare plants in Oxfordshire.
grass of Parnassus about to flower

I also had time for a quick walk around Lashford Lane Fen, the third wildlife trust reserve in this cluster.  A couple of southern hawkers were new for the day, but not enough time to look for scarcer species - the fen is less accessible here too.  It is exciting to see ponies grazing here, helping to manage the fen and keep marshy areas more open.  There are also a couple of colourful meadows full of greater knapweed and field scabious.

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