Wednesday, 30 September 2015

30th September - Eyesight To The Blind

The clear and sunny conditions continue, but if anything the breeze that was with us on Tuesday is even stronger today, and also quite fresh as it is blowing from a north easterly direction.  Unfortunately the clear star lit nights have probably induced any of the migrants around to leave, and are definitely not conducive to anything new dropping in.  With this in mind following and yesterdays walks around the patch I decided I would go back up to Swelling Hill Pond, and see if the dragonflies were about once again, and concentrate some quality time in securing some photographs of them.

As I pulled up I could see one Southern Hawker buzzing around close to the edge of the pond, as it did so it was attacked by a small red dragonfly that was definitely a darter.  I watched the darter fly off and settle on the back of one of the park benches in the sunshine.  This allowed me to get closer, and I was able to identify it as a Common Darter from the creamy yellow stripes on the thorax

The Common Darter is a small restless dragonfly that perches regularly on the bank side vegetation of pools (unlike other darters), but in this case a bench was preferable.  These dragonflies can emerge as early as April, and as late as October and can be seen on the wing as late as November.

There were at least three individuals present, and unlike yesterday I did not see any females.  Here you can clearly see the two bold stripes down the side of the thorax.

The wood by the side of the bank providing a warm surface in the sunshine from which to warm up.

From these resting places the darters would sit quite content until the larger Southern Hawker approached, as the came close the darter would fly up, and despite its significantly smaller size would chase off the much larger dragonfly, and then return to its place of rest.

There were at least three Southern Hawkers present, all flying close to the bank inspecting the vegetation and the holes in the bank

The Southern Hawker is is a large Hawker dragonfly, which is usually solitary which may account for the frequent attacks and attempts to chase the other away.  I was watching males and their flight could be described as purposeful, and regular in as much as it continued to cover the same area at the same height from the ground.  As well as looking for possible prey it searches the inlets and holes in the banks in search of a receptive female.

The strong breeze was blowing the leaves from the trees, and as the leaves fell into the pond the dragonfly would turn and investigate to see if it was a female.

The Periwinkle bank was in the full sun and there were several Speckled Wood butterflies about.  These too seemed to attract the Hawkers and they would chase the butterflies around the trees.  One, though, did settle for a while.

The Hawkers seemed to have their own territories but every so often there would be a raid by an individual, and they would speed off around the pond only for them to split up and one return to the side of the bank.  It was almost impossible to say if this was the original dragonfly or the attacker.  I have since learnt that apparently the males will time share territory of a favourable site with other males, each using the spot from 10 to 40 minutes, however the more males there are the shorter the stint.  

The males clash when they encounter each other, and the outcome is determined by how long their duration has been at the site.  If the male is attacked too early in its stay, the territory is defended vigorously, I saw a pair come together in a fight and you could hear the clash of their wings, the victor returned to the site, while the loser dipped into the water, then flew up into a tree to rest.

The dragonflies seemed to be quite inquisitive of me, coming really close, sometimes far too close for the camera.

I find it quite amazing to look at these incredibly well engineered insects, the wings moving in different directions to control the flight up down, left, right and forwards and backwards, but most fascinating are the way the legs are retracted alongside the thorax keeping them from producing any drag.

Something else I have learnt is that on the face of the Southern Hawker, the arrangement f spots are unique allowing them to be used to identify individuals. You can see the spots here on the front of thehead

If I had known while watching them it could have helped to see if they actually did change over territory duty.

It has been fascinating watching these incredible insects, and I am pleased with the images I have captured too. It was a very nice way to spend a good 45 minutes, in the sunshine.  Just before I left though I noticed the shapes and light that was being produced by the dark water and the lily pads in the middle of the pond.

Turning the dull green lily pad leaves into a mass of silvery plates, gorgeous.

The weather is due to hold until the weekend, but with the chance of cloud later on, this would help with bringing in some birds, especially if the easterly wind continues, and maybe shifts around the south east, we shall have to see

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