Saturday 30 June 2018

The Thirteen Emperors of Bernwood 28th June 2018

I arranged to meet Peter in the main car park at Bernwood Forest at 1030am today for our annual audience with H.I.M (His Imperial Majesty) otherwise known as the Purple Emperor, arguably Britain's most impressive and enigmatic native butterfly. We had to wait for twenty minutes for the sun to come through the clouds but then we made our way onto the main track that runs through the forest and awaited developments.

The track from the car park at Bernwood.The first half mile
is usually the best to encounter an Emperor
As soon as the sun arrived so did butterflies in the form of a couple of Silver Washed Fritillarys, some Ringlets and a Comma, and shortly afterwards I saw an Emperor gliding low along the track towards me seeking out the minerals they like to imbibe from the track. He cruised up and down with regal flicks of his wings but never settled and veered off into the surrounding oak trees and sallow bushes. Nevertheless, this was a good and almost immediate start to a day we were going to devote to the Purple Emperor, such a superlative butterfly, as it descends from its perch situated high in an oak  with great sweeping, looping curves, to fly low and fast along the track, its dark colouring and erratic flight making it hard to follow against the background of shaded summer grasses.

Ten minutes later another Emperor landed further down the track and we hastened towards where it was sucking up minerals from the side of the track, its wings only partially open. It did not remain long before flying again, cruising around at high speed, fairly low over a grassy ride, then frustratingly disappearing up into the surrounding oak trees.

Another Emperor was sighted flying up the track in the direction of the car park and eventually settled but again did not remain on the ground for long, no more than a minute, but giving enough time for me to record an image of its hidden glory, the  lustrous, purple blue iridescence on one of its wings.

This morning was looking very propitious and soon another Emperor came down from the trees to examine the ground and looked to be settled for a prolonged stay. However it was getting crowded round this butterfly as there were not only four butterfly enthusiasts clustered around it but also a party of  ten ramblers who had joined us, wondering what was going on. 

I looked up and two more Emperors were high above us, flying in close formation around the top of one of the large oaks, their size and prolific white markings immediately identifying them, and then yet another cruised low, further down the track and, following it in my bins, I saw that it had landed some way in the distance by the edge of the track.

It was noisy and unsettling with all the chatter from the ramblers encircled around the Emperor we were currently admiring, although you can hardly blame their excitement at seeing and being told about such a spectacular butterfly. The main track through the wood is used by a lot of people, many of whom are totally unaware of the presence of Emperors but if informed of what we are all getting so excited about are just as thrilled as we are to see one. 

Quietly I slipped away from the crowd and walked the hundred metres to where I had noted the Emperor had landed and as I made my way there I put up another that, unseen, had come down to feed on the track. To see this number of  Emperors here was unprecedented but I was hardly complaining as sometimes you can really struggle to see even one. This is the enigma of the Purple Emperor, as it can bring intense joy or disappointment in equal measure. 

I calculated that in a fairly short space of time we had already encountered at least seven Emperors.

I located the Emperor that I had seen flying down the track and fortunately, Peter noting my departure joined me, and we had it to ourselves to enjoy without any possible disturbance. It was in absolutely pristine condition, possibly hatched this morning and I could but admire the velvety brown of its wings and the two orange rings and lines at the extremity of its hind wings. As the Emperor fed, and due to its position on the verge, we were obliged to view it from its rear and the butterfly as per usual  at this angle betrayed none of the famed purple iridescence. Its hidden secret. Its delightful surprise.  

For ten minutes we admired it and it looked set to remain for quite some time but sadly our audience was not to last as some dreaded dog walkers, the bane of any Emperor watcher at Bernwood, arrived and their dog promptly ran up to us and caused the butterfly to flee up into a sallow bush where it crash landed in the leaves, and although perched in a very undignified fashion seemed perfectly happy there before dropping down to the vegetation below. However this lowly location was not to its aristocratic taste and it flew off in less than a minute. 

We hung around for some time but there were no more sightings on this area of track so we decided to walk the whole length of the track, which is a mile and a half. The walk produced three more Emperors which, like the ones earlier, cruised low along the track but settled only briefly before flying off up into the oaks on either side of the track. Notably, one of these was a female. Larger than the male and without any purple iridescence on her wings. Just plain dark brown and white. I say just! She was magnificent! Retracing our steps we came across yet another Emperor which like all the others was restless and unwilling to settle.

Over the years I have found the secret with Emperors is to allow them the time, when they come down from the trees, to find a patch of minerals to their liking before approaching them. This can take some minutes as the butterfly settles and then wanders around on the ground seeking the exact minerals it desires. Sometimes it fails in its quest and then, with a distinctive, fluttering, halting flight will cruise low over the ground, back and fore, seeking another likely spot. This is when the Emperor watcher's anxiety levels reach maximum. Will it settle or will it power off back up into the trees? Seconds can seem like an age. Despite deploying this tactic of wait and see, today the Emperors, with two notable exceptions this morning, had all proved restless and unwilling to settle.

Once an Emperor does find a spot to its liking and settles, virtually nothing will move it until it is satisfied it has sucked up enough minerals and salts. 
Such a moment came to pass as we came to where the track sloped downhill, descending to the little culvert by the meadow and saw four people crouched low over something on the track. It had to be an Emperor and it certainly was, a superb pristine male.

Two enthusiastic ladies were taking pictures of it with their phones and I joined in, getting some nice shots of its underwing pattern but I wanted, as does everyone in any encounter with an Emperor some images of its wings showing the regal purple. This colouring can only be seen from certain angles and to achieve such an image requires careful positioning to get just the right angle in relation to the butterfly. I was getting close to achieving this when one of the ladies got that bit too close in her enthusiasm to get the ultimate image on her phone and the Emperor took offence and flew off. Just another few seconds and I would have got the image I so desired  Here was another manifestation of an Emperor watcher's frustration, in that there always seems to be someone who cannot control their impetuosity.

Satisfied, the ladies walked off and we stood and waited in the hope the Emperor would return but it had been feeding for at least half an hour so it seemed unlikely. An Emperor, possibly the same one, did briefly re-appear but only flew around before departing high into the trees. Two White Admirals cruised around a favoured oak tree on the other side of the track and we watched them as we awaited the possibility of another Emperor coming to the ground. Twenty minutes later we were rewarded as one came to feed on a different but nearby part of the track.

White Admiral
At first it remained with its wings firmly shut although the underside patterning of the wings is, in its own way, just as sensational and enticing but the main aim is to see the male butterfly with its wings spread wide open showing the glorious, wondrous, regal, blue purple iridescence on all its wings at one and the same time.

The iridescence only shows from certain angles where refracted light creates the purple colour. When this happens it is like a bolt of lightening as the light causes the purple to flash for a moment but then the slightest movement from the insect, causing a change of angle, makes the colour disappear just as suddenly as it appeared, as with a light being switched off.

All the above four images are of the same Emperor
The ultimate goal is to get an image of the butterfly showing the purple on all wings at the same moment.When this happens nothing can compare. It is quite superb. 

The Emperor fed on, now impervious to us standing virtually over it. Gently I removed blades and stalks of wayward grass close by it so we could get an uninterrupted image. Slowly I moved around the feeding insect, positioning myself for when it might spread its wings. Tantalisingly it would partially open its wings to reveal a flash of purple but almost immediately closed its wings once more. It went on in this way for some time, the Emperor granting teasing, flickering flashes of purple that were hard to catch with the camera before the wings were closed up again.  Slowly, at last, it spread its wings wide. I was in position and here, after what seemed forever, was the image before me that I  craved and Peter and myself found ourselves looking at the glory of its purple coloured wings, their magnificence visible for all to see. I took many images, far too many, over excitement and exuberance getting the better of me but why shouldn't my enthusiasm carry me away? Here was the moment, by no means guaranteed, that I had been anticipating for an entire year, in fact years as these are easily the best images I have ever managed of a Purple Emperor. Peter too was swept up in the moment but to a lesser extent, both of us excited and happy at this triumphant end to a superb day of Emperor chasing.

We stayed with H.I.M. until he was replete and then he furled his lemon yellow proboscis and wandered a few steps on the track before taking to the air and flew back up into the trees.

We walked slowly back to the car park and yet another Emperor was cruising the short path from the track to the car park. We estimated we had seen thirteen Emperors in a morning, the most I have ever achieved at Bernwood.

I have read on Matthew Oate's Purple Empire web site see here that he thinks this prolonged hot weather is causing the Emperors to come low to seek out the moister, shaded hedgerows as the tree tops are becoming too hot for them.

Whether he is right or not, I can only rejoice in my good fortune. I am going back for more. No question about that!


I went back to Bernwood two days later, on Saturday morning, and saw eight Purple Emperors in a space of two hours but true to the enigma that is a Purple Emperor only one settled on the ground in that time, and then was in shaded long grass where it kept its wings firmly closed and so was un-photographable. All the others were found perched in trees, one imbibing sap from a bough, behaviour which I had heard of but not seen before.

The Emperor on his Throne!

Please click on any image to view a larger version

Thursday 28 June 2018

Hopping down to Kent 24th June 2018

Moth and myself decided on a day out in Kent as there were not one but two Bonaparte's Gulls currently residing there, one at Crossness in that part of Kent which is now classed as southeast London and the other at Oare Marshes, further into Kent proper. Also, as a bonus I could realise a long term ambition to go and see Heath Fritillarys at Blean Woods which is near Canterbury and not far from Oare Marshes.

As we left Eynsham it was a day of yet more glorious sunshine in what is turning out to be one of the best summers we have had for some time in this fickle climate of ours.

A Bonaparte's Gull would be lifer for Moth as indeed would be the fritillary for both of us and we  decided to start with  the first summer Bonaparte's Gull at Crossness as the other Bonaparte's Gull and Heath Fritillary were much further away in deepest Kent.  The first summer Bonaparte's Gull had only recently been discovered feeding at the not so salubrious surroundings of the sewage outfall at Crossness on the Thames Estuary and which is adjacent to Thamesmead, a sprawling area of mainly social housing built from 1960 onwards on the south bank of the Thames. Moth is originally from this part of Kent and confirmed my suspicions that it was not the most pleasant of areas in which to go birding, but that was where the gull was and so we had no choice but to get on with it.

I had directions and a postcode for the Satnav from RBA (Rare Bird Alert) which said that we could view the gull from the Thames Path at Crossness, so presumably it would be easy to find and then we could move on to enjoy the more pleasant surroundings of Blean Wood and Oare Marshes.

My heart  had begun to sink well before we approached Thamesmead as we drove though an urban landscape that not even the sunshine, illuminating dubious sculptures on a couple of roundabouts could make attractive and, following the satnav's instructions, we found ourselves in a large industrial estate and nowhere near the Thames. According to the postcode on RBA and the satnav we had arrived at our destination and the industrial estate was where we should be but we were nowhere near the river. To save a long and tedious account of how we drove round a warren of depressing streets in Thamesmead, lost and increasingly frustrated, all I will say is that after forty five minutes of achieving nothing, we all but gave up.The frustrating thing was we could see a road leading to the Crossness Water Treatment works below the main road that we were on but we could find no way of accessing the road below. Every road we tried was either a dead end or blocked off. 

It was getting warmer by the minute and time was passing, so reluctantly the decision was made to cut our losses and head for Blean Woods. We set the satnav and followed its instructions, directing us through yet more roadworks and past more closed off roads until hopefully we would be able to leave the depressing environs of Thamesmead. Just as we passed the last of the roadworks and about to leave Thamesmead both of us, independently, noticed a road on the other side of the dual carriageway we were currently on that we had not tried or noticed before.

We went to a roundabout and doubled back to the entrance of this road, unhelpfully concealed by traffic cones and temporary road signs and there, would you believe it, was a small sign pointing to Crossness Water Treatment works and the Thames Path. We had found our supposed destination by accident and it had taken an unnecessary wasted hour. If only the directions could have been more specific or possibly I had taken care to get more details about Crossness before leaving home.

We drove down the road, convinced we would be looking for the gull in no time at all and came to an unwelcoming barrier to the sewage works which told us in no uncertain terms to not go any further. Now what do we do? We were so near and yet still so far. I refused to give up.

Turning the car around I drove back a little way to where we could access what looked like a formal  tarmac path that headed in the direction of the sewage works and presumably the river.

'Let's try this.' We commenced a long walk along the pathway and found a sign pointing to the Thames Path.  By now we were passing under a flyover, admiring the graffitti and assorted parts of vehicles scattered around and about. We followed the path but the signs for the Thames Path vanished and we were lost. We returned to stand under the flyover and an uncertain track, through the grass, led off in the vague direction of the sewage works.We had tried every other path so this was our last option. I was not optimistic but we took it.

It looked decidedly unpromising after a few hundred metres as we passed through a hinterland of thistles and scrubby grassland, scented by a pungent aroma from the sewage works. A Rose ringed Parakeet shrieked at us from a tall tree and a Common Whitethroat flew from the thistles. I was all for turning back, as hot, tired and frustrated I found myself in a not very good place both spiritually and physically. Just on the point of turning I saw a man wheeling a bike and walking towards us.

He was the first person we had seen for thirty minutes and I enquired of him the whereabouts of the Thames Path, now rapidly taking on mythical status with us. He told us to keep walking on the track and eventually we would come to it.  

We did as he instructed and after half a mile, walking up a slight incline and through a gate, there was the Thames Path, a fairly wide boulevard of concrete stretching away in both directions alongside the expanse of the river,flowing just beyond a high wall that guarded it. From here it was obvious we should walk to the right, as that was the direction of the sewage works.

Following the Thames Path which was currently occupied by a few cyclists, joggers and us, we eventually came to a ramp that allowed us to walk upwards and view the river through  a screen consisting of a number of viewing 'portholes' set into the wall. The screen was presumably erected to stop people throwing themselves in after a similar experience to ours. There was not a gull to be seen which was unsurprising as this was obviously not the sewage outfall. Further on there was a long concrete walkway running out into the river, guarded by a fortified and heavily padlocked gate, with a circular structure at the end of it. Could this be the outfall?

There were certainly a fair number of gulls perched on the rails of the walkway. We wandered up to the padlocked entrance and looked out through the fortified fence but all the perched gulls were Black headed Gulls and I was none too certain this was the sewage outfall anyway. I looked further downriver and a few hundred metres in the distance I could see some gulls and a tern flying over what looked like a small inlet which was obscured by rank vegetation growing up and around its banks. 'Let's try there Moth and if that is a no go we might as well concede defeat. 'Let's give it a go'.

We walked along the concrete canyon, our view of the river totally obscured by the huge concrete wall on our left and on our other side was the huge Victorian and now preserved, Crossness Pumping Station, designed by Sir Joseph Bazalgette in 1865 and currently  a tourist attraction. 

The River Thames is behind the concrete wall that Moth
is walking alongside
We got to the inlet and walking up another slight incline came to a small grassed area on our left with a wall no more than four feet high overlooking the river. We looked over the wall and there, just below, were about a hundred squawking Black headed Gulls, ranged in a semi circle around the roiling brown turgid waters of the sewage outflow. There was no mistake this time. We had finally found the sewage outfall!

The view to the other side of the Thames with the gulls in
the foreground
The gulls were having a field day swimming around in the brown disturbed water, picking off morsels of, I shudder to think what, and keeping up a constant raucous commentary of calling. Scattered like confetti, in close company, they kept just shy of the strongest  upswelling current as the water bellowed out into the river from the sewage works. Now all we had to do was find if the Bonaparte's Gull was still here. We were optimistic as it had been reported earlier in the morning.

Moth, never having seen a Bonaparte's Gull had little idea of what to look for but knew the bird in question  was a first summer, so it would not have a black head. Fortunately the majority of Black headed Gulls were adults and still in summer plumage with brown hoods and therefore could be eliminated. I scanned through the assembled gulls, once, twice and then a third time but could not find the Bonaparte's. It was far from easy anyway, as the gulls were constantly active, making sudden dabbing movements, picking at the water, back and fore and sideways as the uprising water brought various 'titbits' to the surface. Nice.

First summer Bonaparte's Gull
Using my phone I found a picture of this particular Bonaparte's Gull on the internet that had been taken a couple of days ago by the finder and showed it to Moth so he would have some idea of what to look for. A few minutes later he informed me he thought he had located it! He directed me to where he thought it was and there indeed was the little beauty. Obvious now, amongst the Black headed Gulls, I wondered how I could have missed it. 

Once we had 'our eye in' so to speak, it was relatively easy to pick it out with the naked eye as its demeanour and subtle structural differences gave it away in the throng of gulls.

The gull was fractionally smaller than the surrounding Black headed Gulls. structurally more delicate and to my mind was a slightly darker grey on its mantle. Its bill was black and its feet and legs flesh pink while its white head was sullied with black smudges. It swam amongst the other gulls, unphased by them and quite feisty, fully prepared to threaten with partially open bill any gull that came too close, and it fed in a similar manner to them, delicately picking morsels off the turgid water. 

The Bonaparte's Gull with Black headed Gulls
Its feeding action was faster  than the other gulls and vaguely reminiscent of a phalarope, as it made quick darts and stabbing movements to either side and in front whilst rapidly paddling. It came close  on a number of occasions and then drifted away to the outer peripheries of the flock, when it would  fly back into the main congregation of gulls and the whole process would be repeated ad infinitum. Its wings, when it flew showed the diagnostic pure white undersides on the outer primaries and in flight I could see it had already commenced its wing moult on the inner primaries.

Bonaparte's Gull and adult Black headed Gull
Bonaparte's Gull in flight with swimming Black headed Gulls. Note the
strange shape of the outer wings due to the wing moult on the inner primaries

What a smashing little bird and we savoured the reward of the righteous after our marathon logistical effort to get to see it. A couple of recently fledged Black headed Gulls, still in their mixture of pale ginger brown, grey and  white plumage were amongst the flock but already beginning to moult into the standard grey and white plumage of a first winter bird.

Adult and juvenile Black headed Gulls

A small flock of Common Terns fed with the gulls but unlike the gulls that swam on the water, the terns remained in the air, circling overhead above the most turbulent part of the outflow, diving down with sharp cries to seize a food item, hitting the water with a resounding splash. At first there were only three Common Terns but slowly the number rose to around fifteen. Similarly the gull numbers also rose while we watched.

Common Terns
We lost sight of the Bonaparte's and then re-found it. We took its photo and generally indulged in a bout of self congratulation for about forty minutes, having the gull close to us and giving exceptional views, before we were joined by two other birders. 

'Is it showing? they enquired. 

'We have brought some bread.'  

'You won't be needing that' I replied. 

Pointing, I said, 'It's over there at the back of the flock  but it will fly in closer if you wait'.

It did just as I said and we left as it was now lunchtime and we had another ninety minute car journey to the RSPB's Reserve of Blean Wood.

We walked back across the waste ground with me wondering if the car would have all its wheels still intact, as the place where we had left it looked none too secure. I need not have worried as it was all in one piece and with relief both of us headed out of Thamesmead and towards a more rural and enticing part of Kent.

After a slight hiatus we found the RSPB's entrance to Blean Wood. I was unsure what to expect and certainly did not know where to look. In the end we opted for just following a track and trusting to luck. Heath Fritillarys are very rare, due in the most part to loss of habitat. It has very special requirements that are based on regular coppicing of its habitat, something that has died out with modern forestry practices. It requires rotational clearing of the ground so there is a succession of suitable habitat that encourages its foodplant, Common  Cow-wheat, to grow and where the butterfly can move, once its current habitat becomes unsuitable. 

Heath Fritillary habitat
These cleared areas were fairly obvious on the reserve but we could not find any sign of a fritillary but only the occasional Meadow Brown or Ringlet. Undaunted we carried on searching the cleared areas where they were in sunlight. After about half an hour Moth spotted a small ginger coloured butterfly with darker chequering on its wings, flying very low above the track we were currently standing on. The butterfly settled briefly on a bramble flower and there was a Heath Fritillary, a first for both of us.

Heath Fritillary
It was smaller than I expected but nevertheless I was very pleased to see it. We stopped here and over a period of forty five minutes we saw a small number, probably no more than ten Heath Fritillarys, coming and going from what was obviously a favoured area. Most were males flying endlessly, looking for the females that hide in the low vegetation but the males too would settle briefly to nectar from bramble flowers and this was our opportunity to get some photos.You had to be quick as they did not settle for long before flying off, always low to the ground searching for females.The ultimate prize in any fritillary photo is to get an image of the underside of their wings, as this is where the beautiful marbling of irregular white markings can be seen.

Having got our photos we wandered the various trails and found a little further on a White Admiral cruising in its distinctive gliding flight through the surrounding trees and eventually it too settled on some bramble to suck up the nectar from the flowers and Moth got yet another lifer. Such beautiful and elusive insects, they, in my opinion, have the most lovely patterning on their underwings of any of our native butterflies.

White Admiral
The White Admiral eventually flew off, powering away with a few flicks on  flat wings and we walked on but saw little else apart from a couple of Painted Lady butterflies.We went back to the Heath Fritillary 'hotspot' and spent another twenty minutes there with one very tatty male, his wings torn and scuffed and who had not long to live.He returned time and again to some ferns by the track, basking on the green shiny fronds in maybe the last day of his short life.

Energised by our success with the Bonaparte's Gull at Crossness and the Heath Fritillarys at Blean Wood we decided that we would try for the other Bonaparte's Gull, an adult this time, in full summer plumage, at Oare Marshes just half an hour's drive away. Oare Marshes is a seventy acre Local Nature Reserve owned by Kent Wildlife Trust and located on the south bank of the Swale Estuary. It has a feeling of remoteness and calm, almost a step back in time, despite its proximity to the town of Faversham. It has been years since I have visited here but we found it with little problem and parked by an area of open water, reeds and a couple of islands called The East Flood. This is where the gull had been reported from earlier in the day but there was no sign of it now.

Two separate flocks of Black tailed Godwits were roosting here, some still in their barred and rusty orange breeding plumage with a few Avocets among them.

Roosting Black tailed Godwits
One of the flocks was roosting on a small island and, very much obscured in amongst them, was a small grey and white gull with a distinct black rather than brown hood. This had to be the adult Bonaparte's and indeed it was, as eventually it woke up and turning its head, showed off its black bill.

Adult Bonaparte's Gull in amongst the Black tailed Godwits
I would have liked to have seen more of it but shortly afterwards it flew high in the sky and far away, following the Oare Creek and we decided to leave matters there as it had been a long but rewarding day and there was now a three hour drive in prospect to get back to Oxfordshire.