Wednesday, 8 June 2011

Quest for Common Blue - Far Pasture revisited

A bright morning gave me my only probable opportunity of the week to do a bit of dragon hunting, the forecast was for clouding over late morning then showers, so a quick visit to Far Pasture ponds in the hour or so I had free was the best option, another chance to catch up with common blue damsels and four spotted chasers, with four having been reported here at the weekend.
The hide was empty, I opened a few windows on all sides and sat down to scan with eager anticipation. Sun was shining but disappointingly neither dragon nor damsel to be seen. And so it remained this way for a good 15 minutes, I consoled myself with an update on the birds present, far more action of the feathered kind than has been seen here in a long while.
Birdsong abounds, the chuntering of a garden warbler, the scratchy verse of the common whitethroat, the staccato song of a reed bunting, distant willow warblers and chiffchaffs, lovely stuff.
The water treatment plant next door had attracted many a hirundine, mainly house martins, wheeling around the skies picking off the myriad of insect prey these places are infested with.
Two broods of mallards, one quite duck-like, the other still in the fluffy cute stage, a moorhen family, territorial coots chasing anything that came near the nest, a pair of loafing Canada geese and a female tufted duck. And the little grebe nest was now empty, both adults were about, fishing in the clear waters and taking their catch into the reeds, so I guess the recently fledged chicks are in there somewhere. Ah the spring, but where are my dragons?

My wait ended with a flurry of activity, scanning the nearside vegetation for anything perched up, a pair of damsels in tandem floats past my eyeline, the blue male in front clasping his green female around the neck as she’s towed along. But they disappear just as quickly as they came and my attention wanders to a dragonfly which has just appeared directly in front of me, dipping it’s rear into the pond, a female four-spotted chaser ovipositing (egg laying). Maybe 5 or 6 rapid dips then she exits stage right as two more dragons zoom past further out going right to left. Their stop-start flight pattern has me dizzy, I can barely keep up with them with the naked eye never mind binoculars. They are joined far-side by another, all three hover in a group just long enough for me to get a fix on them, they are all dull brown four-spotted chasers, much duller than the yellowish female I have just been watching so I believe them to be all males. A brief skirmish and they zoom out of vision in all directions. Every now and again I can track one but they don’t ever seem to perch anywhere so offering no opportunity for better observation or photographs, and so it goes on for a while.
I relocate my blue damsel couple who are now ovipositing on surface plants. Female with abdomen arched as she lays her eggs, male still clasped round her neck now vertical as if on sentry duty. They are soon up in the air again and land on a plant in tandem a bit closer to the hide, giving my first photo opportunity. At 18 x zoom at about 20 feet away I can’t get good clear images, but the magic of digital is you can reel off a few in the hope one might give clues to their species, then nearby I locate a single blue damsel which I photograph as well.
Time running out now I scour the pond margins in front of the hide and find a second couple in tandem, again unable to identify by sight I get a couple of photos and it’s time to go back to Dragonhunter HQ and study the pictures.

Azure couple - U shape at top of male abdomen is clearly visible

Another Azure couple - subtle differences on the male but the all dark back of the female abdomen is the best clue, on common blue the dark markings would be bomb shaped, but will cover that later.
There’s enough evidence on even these poor quality photos to confirm both couples I saw were azure damsels but what about the single male below, at first glance no different from the azure damsels we’ve observed so far, but then look at the side by side comparison with an azure I’ve already photographed and see why in fact we have at last got our first Common Blue damsel of the year.

Single blue male but what species?

He's a Common Blue Damselfly Enallagma cyathigerum 
The mushroom shape is just about visible on segment 2 of the abdomen but compare with Azure damsel above,
the single black stripe on the thorax (body) is a lot thinner, and at the tip of the abdomen there are two complete segments coloured blue on the common, wheras the outer segment at the tip of the azure is half black.  
So there it is, just goes to show the value of photographing and asking questions later, even with poor quality snaps like I’ve taken, there are enough clues to confirm ID. I have no doubt I’ll get much better images as the season draws on and will do a proper comparison of the species at a later date, in mid-summer they tend to couple up away from the pond along the access road in good numbers, making locating them and photographing them a lot easier. Meanwhile another mission accomplished.

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