Thursday 14 June 2018

Getting the Blues in Gloucester 13th June 2018

It was sunny this morning and fresh from my exhilarating trip to see Black Hairstreaks in Buckinghamshire, I was fired with enthusiasm to go and see a Large Blue, another charismatic native butterfly species that is also very rare.

Fortunately for me they are to be found fairly close to my home at a place called Daneway Banks in Gloucestershire which is an SSSI (Site of Special Scientific Interest) and managed by Gloucester Wildlife Trust. So on a sunny morning I made the forty five minute trip through the pleasing countryside of the Oxfordshire and Gloucestershire Cotswolds.

I parked in the tiny layby that is near to the Daneway Inn and crossed the stone bridge over The Severn and Thames Canal, that runs through the bottom of a deep and secluded valley, then made the stiff walk up the winding road on the other side to the entrance to Daneway Banks, which comprises part of one side of the valley and is now made into a reserve catering for a wide range of insects and flora, including the Large Blues.

Large Blues became extinct in Britain in 1979 due to the depressing and all too familiar reasons of unsustainable, relentless collecting and habitat loss. Thankfully Large Blues from Sweden were found to be identical to the extinguished British race and a re-introduction programme using Swedish specimens commenced in England in 1983, resulting in some being eventually re-introduced to Daneway Banks in 2002, after an absence from the county of around forty years. They now thrive there, with enthusiasts coming from far and wide each year to see them flying.

As its name and location would indicate, Daneway Banks is an open grass area of seventeen hectares comprising steep upper slopes of oolitic limestone with terraces of flatter, dry, short grassland below, that today was a mass of yellow flowers due to the abundant presence of catsears, rock roses and horseshoe vetch with patches of thyme, clover and scattered outposts of Pyramid and Common Spotted Orchids adding their varied purple and pink colours to the predominance of yellow.

Up to my arrival it had been sunny but now light cloud obscured the sun and a stiff breeze blew over the open expanses of the reserve. A few butterfly enthusiasts were already wandering about on the reserve as I passed through the entrance gate but no one had located a Large Blue. It was still comparatively early, about nine thirty and the mildly overcast conditions were none too helpful but separately we pressed on, strolling through the grass and flowers looking for any sign of a Large Blue.

Little butterfly action was evident apart from Common Blues rising up from the short sward before being carried off on the breeze and each sighting of one brought a brief hope they might be the prize of a Large Blue but we were always disappointed.

Male Common Blues
Two enthusiasts claimed to have found a female Large Blue and we clustered round to see but before any of us could locate it in the grass one of them idiotically stuck a camera phone right up to it and it flew off. Judging from their conversation I do not think it was a Large Blue but a female Common Blue and I walked off reflecting on their inconsiderate behaviour but it is a two edged sword. Often it is the finding by someone else that alerts you to a Large Blue and you share the sighting but it needs all person's present to know how to behave in such situations.

I strolled on, right to the end of the reserve, climbing and descending the steep slopes, wandering the flatter areas but for two hours I saw absolutely no sign of a Large Blue and nor did anyone else. Maybe we were a little early in the day? The sun shone for intermittent periods but even when it did it was for a few minutes only and then butterflies did appear but not a Large Blue. Common Blues were fairly frequently seen by contrast and as the air became warmer I found one each of those tiniest of our native butterflies, a Small Blue and a Brown Argus. Meadow Browns were also about in good numbers and a single Marbled White added to the variety as did a number of Orange Underwing and Silver Y Moths.

The only highlight in the first two hours was a single Greater Butterfly Orchid, found growing by one of the tracks through the grass.

Greater Butterfly Orchid
Having walked what seemed miles on the steep and uneven terrain I was growing not only disconsolate but weary too and considered giving up and coming back on another day. I sat on the grass to rest for a while when another enthusiast nearby called to me. He had found a female Large Blue, secreted deep in the grass on a small bank, laying eggs on a flower head of thyme and I hurried over to join him. It was a Large Blue alright but not in very great shape, its wings tattered at the edges and the colours faded and worn. It was disappointing on one level but at least I had finally connected with a Large Blue. After a minute or two it flew but not very far, fluttering low, looking for more thyme on which to deposit more eggs and eventually landed on some flattened grass near to some thyme by a bare track, there to plainly display its worn and frayed wings, held wide open to absorb whatever warmth was available from the recalcitrant sun as it searched for somewhere suitable to lay more eggs.

The female Large Blue laying an egg on some Wild Thyme.
Note her body bent over to deposit the egg in the flower
The female Large Blue which clearly had seen better days
Then, as often happens, we found another Large Blue almost immediately but this time a prime specimen not showing any signs of wear and after a few tense moments, wondering if it would settle or not, it landed. A real beauty, it clung to the grass with its wings closed but then opened them wide to display the black edged steel blue colouring on the wing's upper surfaces together with the diagnostic and very distinctive black spots on its fore wings. A real beauty and for a minute or so it remained perfectly posed but then flew to a nearby spot and yet again someone had to remove that particular stem of grass to get his photo with the result it was disturbed, flew off and we lost sight of it.

Large Blue
We searched around for some time but it had given us the slip.The offending photographer also sloped off without a word of apology or remorse. Those of us left remained philosophical and we commiserated with one person who joined us and had never seen a Large Blue. He would have done but for this example of inconsiderate behaviour. I found a Great Green Bush Cricket in the longer grass which briefly entertained us with its no nonsense attitude and a dapper Garden Chafer with bottle green head and thorax and shining bronze wing cases mounted a nearby grass stem and took flight, stooging away, none too steadily, across the sward.

Great Green Bush Cricket

Garden Chafer
It was pointless fretting too much about the avoidable disappearance of the Large Blue and I climbed slowly up an adjacent steep slope to where scattered mounds of purple thyme grew across the slope. 

It was more sheltered from the wind here and as a consequence warmer. Also, thyme is the foodplant of the Large Blue larvae and on which the females lay their eggs. Maybe there was a chance that one would come along if I waited here, and as my feet hurt from all the walking I had done this seemed a very attractive proposition. So I sat and waited and it worked like a charm. In the next hour I saw at least ten Large Blues as they came fluttering along the bank. Some settled on the thyme and others flew on. Some opened their wings wide and others kept them firmly closed. I noted the different intensity of black spotting on their upperwings which is meant to denote whether they are male or female, the males show less spotting and narrower black edging to the wings. One, a female I think, remained for at least half an hour on a blade of grass, apparently asleep, and then opened its wings for a minute before deciding to close them again and resume its dormant position on the grass.

Probable male Large Blue

Probable female Large Blue
The cloud cover became thicker and darker and it looked like the sun was not going to be in much evidence for the rest of the day. A single, silent Raven flew high over the valley. I looked at the time. It was one thirty. Four hours had passed. It was time to go.

Another pleasing and successful day.

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