Large Blue Is On The Wing

 Despite the forecast suggesting an increasing risk of thunderstorms and thick heavy cloud I decided on the spur of the moment to head down to a butterfly reintroduction site in south Somerset. My quest today was to see if the large blue [Phengaris arion] butterfly was on the wing - I was not disappointed.

I last visited this site two years ago when after a sizzling few hours of frustratingly seeing but being unable to photograph large blues, I realised later when at home that I had actually managed to take a photograph of a motley specimen after all.   Two years ago it was quite late in their flight season, today however I hoped to be there at the beginning of the season. Looking on-line I had only seen a couple of sightings posted. 

As luck would have it when I arrived it was spotting with rain and quite cool, certainly different to the last few weeks of hot dry sunshine. But that lack of rain shows on the ground as everything here was baked hard, cracks you can get fingers down in the thin soil, and more worrying many of the ants' nests that are crucial to the survival of the large blue looked like they'd been broken open and robbed by presumably badger, green woodpecker, or maybe even foxes. There were intact ants' mounds around but a quick scan revealed at least half of the mounds were broken apart or damaged. One even had a fresh badger tunnel dug into it.

It was noticeable on first walking onto the reserve that it looked like it had gone back a little since my last visit, with quite a noticeable increase in scrub. The once prominent signs directing people to the site have gone too, did they attract too many visitors? When the large blue were first introduced here the site was kept secret. The then recently installed horse gallops half way up the hill have also been abandoned by the looks of it which is a good thing I'd suggest, as what was mown turf and artificial gallop material on my last visit is now quite overgrown. Not good for the large blue, but reverting to wild for more generalist species, like this small heath, which intrigued me. It was stationed on some sheep's fleece for ages. I'm assuming the fleece lanolin is providing minerals of some form, but I can't recall seeing butterflies on fleece before - I've probably not looked to be honest.

The main path pushing further into the ancient downland area is now overgrown meaning I had to divert downhill a little where I spied a very familiar object. Either this is for a training day or a transect is about to happen.

Having pushed through the scrub, snagging myself a few times on the dog roses now growing everywhere, my first large butterfly of the day was one or two  meadow brown, which proved frustratingly hard to get a decent image of.

It was while trying to snap a better image of the meadow brown that a blue butterfly flew past at speed at knee height, a common blue by the lighter colour of it, large blue do look sooty blue on the wing. It was gone before I really registered it, with just my mental filing system dismissing large blue. Spots of rain were still falling and while those species I was now seeing were proving fascinating I did wonder if I'd come too early, on a day with the wrong weather, to see my target species. 

Planning to walk on a little along this forty degree slope, I looked down to check my footing and there, right next to my shoe, a large blue.

I only had time for a very quick record photograph before this beauty rose and flew off to join what I think were three maybe four large blue quartering the exact same place I 'd seen them two years ago. I now had got my eye in. The cooler conditions were making them less mobile than I feared they may be which allowed for a number of close encounters, (though not too close for this protected species). 

        

To be honest it was near impossible to know how many were in front of me. Definitely four, but I'd struggle to say more in this first area as they were being both very mobile and quite sedentary once they settled. Those resting on thyme with wings open were really easy to spot, that dark Wedgewood blue really does punch out from the short downland vegetation.

Once I'd fired off a dozen or so images I relaxed and just watched them going about their business without me looking through the viewfinder. This is the closest I've been to newly emerged large blue and I can appreciate, though don't condone, why Victorian naturalists craved this species for their collections. Newly emerged as these were they are absolutely stunning, a thing of beauty.

This female is egg laying on thyme

Within half an hour I'd seen more large blue butterflies than in my entire lifetime. As I sat for a while just taking this all in I began to wonder how these now-naturalised 20-30th generation differ from Swedish stock they originated from. Maybe they don't. 

However insect evolution can be rapid due to quick birth-develop-adult-breed-die generations. Yes these blues in Somerset are not from a British stock, but they are the same species as the ones brought over from Scandinavia, yet have these now English emerging adults begun to adapt at all, adapting to survive on a dry south facing slope in Somerset? Is the interaction with the ants identical? It's a thought.

I'd read this week that although large blue colonies are faring well across the UK, this site having previously been the best place in Britain in terms of large blue abundance, has suffered a little. Although there is still a healthy population here, a succession of less favourable winters, wet and cold springs and prolonged periods of drought have reduced numbers significantly. Though, as someone who studied statistical analysis in conservation for my degree all those years ago I ask myself is any of this change statistically significant? 

Is it a worry given what I saw today of the desiccated and smashed ant-hills and the concrete hard baked soil? The number of butterflies on the wing today was good, I found more on my way back in another area, counting five at least, three spiralling on the wing. But without some much needed rain, will the ants, the host flowers and the area itself be productive enough to sustain this fragile butterfly at the north-western edge of it's range? I'll leave that question hanging there while I revisit this image of a remarkable and stunning species brought back from extinction.