Since it’s arrival nationally along the Thames estuary in 2010, Blue-eyed (or Southern Migrant) Hawker has colonised the British Isles widely and rapidly. It seemed only a matter of time before the first records occurred for my home county of Oxfordshire and that has now transpired. The event has prompted great interest in local natural history circles, and the dust having settled since the initial discovery on 15th June I myself have been to take a look.

Later in this day (22nd) it was confirmed there are now three individuals, two males and a female (see here) at the location along the old River Ray near the village of Oddington in the Otmoor basin (SP 5523 1404). In the morning I had met Ewan at Bucknell Wood, Northants to progress that part of the annual national butterfly agenda that involves Purple Emperor and White Admiral. When I said I was stopping at Otmoor on the way home he came along too, then on our arrival Badger (Oxon Birding web administrator Jason Coppock) was already in place ahead of us filming our quest (pictured below) that he put us straight onto. Things today were as simple as that.

Blue-eyed Hawker (immature male) near Oddington, Oxon

I had previously observed adult Blue-eyed Hawker in Essex at Wat Tyler Country Park, Basildon (Aug 2015 – see here) and Canvey Island (July 2017 – see here). The opportunity to experience the immature colour form on offer locally now appealed to me considerably. I am unsure whether my picture shows a male or female and would be grateful if more skilled county colleagues could gender it for me in comments. By way of explanation I prefer to use standard international dragonfly names, in this instance “Blue-eyed” Hawker over their sometimes rather idiosyncratic British Dragonfly Society (BDS) equivalents of which “Southern Migrant” Hawker is one.

The history of this species in Great Britain goes something like this. After a single confirmed record during the 20th century, four individuals were found in southern England during 2006. In 2010 many more were observed in south Essex and north Kent, with egg laying being noted at two sites (per BDS). Since then, what had previously been a dragonfly associated with the Mediterranean region of southern Europe has been recorded as far afield from its British entry point as Cornwall and Yorkshire, as well as many other places in between.

Blue-eyed Hawker (immature male)

Once my two companions had gone their separate ways today I took a little time over taking pictures of some other dragonflies along the bridleway back to the village of Noke, where I prefer to park discretely if visiting Otmoor. The area around the old River Ray weir, just west of the RSPB reserve is especially productive for Odonata and teemed with maturing Ruddy Darter (pictured below) and blue Damselflies on this occasion, while occasional Brown Hawker and Blue Emperor also buzzed by. It was close to here that another county first record, that of Blue (or Scarce) Chaser occurred in July 2014, so the location has some form locally.

Ruddy Darter (imm)

Ruddy Darter (maturing)

The yellow-toned studies above show immature Ruddy Darters, while the redder individuals in the bottom row are some way to acquiring their adult colouring. There are huge numbers of this dapper little dragonfly in the Otmoor basin each season. It is one that I always find especially attractive and photogenic, and so never tire of attempting more pictures of.

In the morning at Bucknell Wood (SP654450) we did not come across any Purple Emperor, though the first Oxon records for this season had occurred at two sites a day earlier. Pristine White Admiral were indeed a feature, but like the Blue-eyed Hawker could only be captured pictorially (below) looking into the light.

White Admiral

White Admiral

Wood White

Wood White

Still fresh Wood White (above) were again plentiful at the Northants site that is a stronghold for them (see here). I cannot recall having observed them so late in June previously, not having made the effort to do so. This is a site I intend to pay more attention to in the weeks ahead to track the progress of Wood White through its second brood. Today had been quite an energetic step in that direction.

At this time of year when the daylight hours are at their longest I tend to wake with the light. So on this particular sunny early morning, having completed some early chores I opted to re-experience a British butterfly I have avoided since 2015. Two Oxon wildlife colleagues had made the same tripette ahead of me without reporting the circus that had so put me off on my previous visit to Daneway Banks. So I took a chance both on presently unpredictable weather conditions and another disagreeable outcome.

After arriving on site (SO939036) around 10 am I headed up to its highest part where I had been told my quest might still best be located. In the by now lightly overcast, mild and calm conditions this reserve simply teemed with seasonal butterflies – Marbled White, Meadow Brown, brown Skippers and a few Ringlet – but it didn’t take long to notice a first Large Blue in the grass to one side of my footfall. There was company, but thankfully those other observers were all genuine butterfly enthusiasts.

Large Blue

Thereafter, as I walked on something else distinctly blue would stand out every so often from the more commonplace fayre. And each Large Blue I encountered seemed to pose a little more pleasingly than the previous one. On the hilltop there is a cordoned off area to prevent breeding habitat from being trampled, but in the accessible margins around it, where there was plenty of the food plant Wild Thyme, I eventually estimated self-finding 14 individuals. For much of the time I had those to myself and was able to enjoy true communion with them, unlike on that 2015 visit.

Large Blue

Large Blue

Large Blue

Daneway Banks is owned jointly by Gloucestershire Wildlife Trust and The Royal Entomological Society, who work in partnership to manage it as a nature reserve and a place for ecological study. A steep, south-east facing hillside above a dry valley on the north side of the River Frome, the upper slopes of the 17 hectare (42 acre) site are an example of prime limestone grassland. That habitat and areas of ancient Beech, Yew, Hawthorn and Hazel woodland have long been considered exceptional for biodiversity even by the high standards of Cotswold grasslands. SSSI status arises from the great plant variety including calcareous-specific species.

The main sward is interspersed with patches of scrub and woodland, occasional cliffs and scree from small abandoned quarries. Across the lower parts of the hillside, Jurassic limestone soils are replaced by neutral Fullers Earth clays on which fewer wildflowers grow. Up to 10 different Orchids bloom here at different times of the year, as well as regionally rare plants including Angular Solomon’s Seal and Mountain Bedstraw, and two national rarities Cut-leaf Selfheal and Cutleaf Germander.

From mid-autumn to spring the site is grazed by sheep and ponies, so by late winter the sward is predominantly short with scattered taller patches. The land is then left un-grazed through spring and summer, allowing a succession of wild plants to bloom and set seed, and for insects to breed. Thousands of Yellow Meadow Ant hills, known locally as “Emmett Casts” are a prominent feature.

Large Blue

Large Blue

But it is the now thriving population of Large Blue (pictured above) in June and July that attracts most visitors to this remote and scenic location. The Cotswolds was one of three main regions where the butterfly bred before its extinction as a British species in 1979. In tandem with appropriate habitat restoration by a consortium of scientific and conservation organisations, re-introduction then commenced of a near identical Swedish race into Devon from 1983 then Somerset and Gloucestershire from 1992. Over 25-years these butterflies spread to more than 30 sites, mainly in Somerset. Although most were small satellite colonies, the core populations were very large for this rarity, exceeding known numbers anywhere else in the world.

In the Cotswolds this re-colonisation struggled, however, The earliest introductions at Butterfly Conservation’s Rough Bank reserve (SO913087) and Barnsley Warren SSSI failed because the adult butterflies emerged too late to synchronise with flower-bud production of Wild Thyme. So ovipositing females had to rely on occasional late-flowering plants growing in the coolest spots within sites. In Somerset spring and summer local climates more closely matched the source sites in Sweden, so the synchrony was imperfect but adequate. In the Cotswolds, where temperatures were a further half degree cooler, it was not. Such is the fineness of the tolerances that were involved.

Large Blue

Large Blue

So the story goes this is a tale that must be told … and all that. Large Blue larvae famously grow as parasites within the nests of a particular species of red Ant. After some initial development on Thyme and attaining the minute proportions of their Ant counterparts they are “adopted” by foraging Ants that are tricked into taking them home. This is achieved by emitting a secretion to attract Ants who think they are their own larvae. Once in the nest the butterfly larvae feed on the Ant grubs, often destroying entire host colonies.

At Daneway Banks, despite under-grazing by livestock in the 1970s and 80s sufficient Wild Thyme remained to support increased populations of the said Ant, with appropriate habitat management. So the site was identified as a more promising one for restoration than its Cotswold predecessors, and through the early years of this century Ant densities increased and Thyme spread under targeted grazing. I am being brief in this summary. For more detail in the Royal Entomological Society source article by Prof Jeremy Thomas see here.

Large Blue (all pictures)

From 2010 continued re-introduction of the European Large Blue at Daneway Banks has been more successful still. The site now supports one of the largest populations of this globally endangered butterfly anywhere across its range, and is widely regarded as one of the best places to see the iconic species. I came back six days later on 23rd to fully explore this beautiful reserve. In much sunnier conditions the Large Blues were far more flighty and less inclined to perch openly, but I still gained some more images (above).

Marbled White

Meadow Brown

I also paid some attention this time to Daneway Banks’ more common butterflies. It is difficult ever to tire of attempting more under-side studies of Marbled White as they display their geometric intricacy atop as attractive flower heads. But one of the morning’s better picture opportunities was a little Meadow Brown dinner party (above right).

The evidence of these two excursions was that a more peaceful co-existence is now being achieved regarding visitor pressure than the situation that so discomfited this particular observer five years ago. So these were the most positive of my own five national Large Blue experiences to date, and ones that I thoroughly enjoyed.

It was a huge relief to hit the road this morning on a birding twitch, for the first time since mid-March. There are not too many of what I term “annually occurring” small migrant European passerines that I still require for my life list, and I scan the national bird information services each spring and autumn in the hope of gaining such records. Amongst those birds in recent seasons have been Aquatic, Blyth’s Reed, Greenish and Marsh Warblers; so when the last of those turned up just 70 miles from home over the weekend it was a must see.

Marsh Warbler disappeared as a national breeding species through the latter part of the 20th century, and must now be regarded as a rare and local annual visitor. By the 1970s it bred in significant numbers only in Worcestershire, where 40-70 pairs were recorded annually. A very small population then developed slowly in south-east England and especially Kent, but both these clusters were effectively extinct by the turn of the century. Most records in the British Isles now occur in early summer and this post’s bird was one of 17 individuals logged in the British Isles over the previous seven days.

Marsh Warbler © rights of owner reserved

MW breeds in rank herbaceous vegetation, often besides water courses and ditches or on damp wasteland, and sometimes on the fringes of reed beds. It occurs through middle latitudes of continental Europe from eastern France and into western Asia. This bird is very similar to Reed Warbler in appearance but the song is quite distinctive (see here). Collins describes this as “a stream, broken by brief pauses of whirring, excitable and whistling notes with for the most part high voice and furious tempo”. Singing males are notable for expert mimicry of as many as 75 other European and African bird species. On closer study these prove to have been learned in their first summer and are not added to in subsequent years.

Today’s individual was first reported on Saturday evening (6th) but I thought better of going for it on a Sunday when the site might likely have been crowded with non-birders. Having listened to the song on-line, I recognised it as soon as I arrived at King’s Meads (TL351139) around 7:50 am this morning. The sound was coming from water meadows between a canal towpath and the River Lea, in which I could see just two birders. They were standing in a spot that had been flattened by presumably many more a day earlier and so I went to join them, being careful to tread only where others had before me.

The song continued to issue from a bush (pictured above) a short distance before us, but I suspected the bird itself was on the far side. Three more birders then approached along the towpath and soon their body language suggested they had located it. One of them indeed beckoned and so we went to join them. Before too long the Marsh Warbler sat up singing in the top of the bush, and my mission for today was thus accomplished. Things were as simple as that. For the RBA gallery of this bird see here.

King’s Meads (see here) comprises 96 hectares (237 acres) of grazed riverside flood meadows, criss-crossed by water courses and ditches. The site lies between the neighbouring towns of Hertford and Ware, and is maintained as a nature reserve by Herts and Middlesex Wildlife Trust. I remained there for around an hour, during which my quest showed well on and off in the top of it’s adopted home, pouring out that rich and curious song throughout.

So now the dwindling residue of bird lifers that I might realistically encounter within my preferred range nationally has been reduced by one more item. A second Marsh Warbler for Herts turned up at Stocker’s Lake (TQ046937), Rickmansworth later on this day, but I had already heard and seen my lifer well in Ware and so was satisfied.

In a season of BT Sport-style repeats where this journal’s butterfly content is concerned, it seems appropriate to cover this bold larger Fritillary of early summer for the first time since 2015. Evolution and hence motivation are coming in part from observing local species at new sites, and my first location of choice this year was the south-facing slopes of Watlington Hill NT (SU702932).

A personal first site record of two Dark Green Fritillary was gained on 29th May, along what I term the “back way trail” that runs downhill from the NT car park. That is a sheltered route that can be very butterfly rich in high and late summer, and is less used for recreational activities than the hill top and its west and north-facing sides. In 2020 I have also secured site firsts of Dingy and Grizzled Skipper, Green Hairstreak and Adonis Blue here.

Dark Green Fritillary at Watlington Hill, Oxon

Returning on 2nd June as the day warmed up, it didn’t take long to come across what I assumed might be the same two DGF again posing nicely in the very well-managed track-side habitat. These were offering mainly under-side studies as the following sequence shows. Then walking around the open chalk hillside above the trail I estimated counting around 14 individuals in all, though no doubt more were present across the entire site.

It is the under-side patterning (pictured below) that gives this butterfly its name. The whole of the background to the inner two-thirds of the hind-wing is flushed with an attractive olive green, the intensity of which may vary between individuals. The silver patches around the hind-wing edges are also bordered with green crescents.

Dark Green Fritillary

Dark Green Fritillary

The next day, the prolonged spell of unseasonably fair weather that had accompanied the Covid-19 crisis in Great Britain, almost like a parallel “Act of God” to make things more bearable for the incarcerated populace, abruptly changed. In the interval between this post’s two dates temperatures halved, while overcast conditions, strong cold winds and at last some rain was welcome respite for my garden at home but hardly butterfly friendly.

On 7th the first few hours of morning were forecast to be sunny again and so I headed for another Chiltern escarpment site to the north of that first choice. Bald Hill is part of Aston Rowant NNR (SU723959) and classic chalk downland habitat. Both Ewan (see here) and another wildlife colleague had come here to observe DGF before the weather changed, so from their reports I was expecting good numbers of butterflies on my own visit.

Dark Green Fritillary

Dark Green Fritillary

Arriving around 9:30am for the usual reason that my quest might be warming up with the morning, the first large Thistles I came upon were adorned with two pristine Dark Green Fritillary. This is a superbly photogenic butterfly and given to posing openly, especially when fuelling up for its day on the nectar of an equally photogenic wild plant. But it was just as well I captured acceptable under-side studies at that previous site, because today my subjects just were not offering them.

Dark Green Fritillary

Over two and a half hours on site I made a slow circuit of the hill. At the next large clump of Thistles three more DGF (pictured above) were posing as nicely as those earlier two, and in all I may have counted up to 20 individuals. But the showy Thistles were not their only nectar source of choice and some butterflies also offered ground level portraits.

Dark Green Fritillary

Dark Green Fritillary

Dark Green Fritillary

Dark Green Fritillary

Dark Green is cited as the most common and widespread Fritillary across the British Isles. As well as unimproved chalk and limestone hillsides, the species occurs in almost any flower-rich open habitat, especially where the sward is regularly disturbed by grazing animals then left to recover. Such places might include rough pasture, woodland clearings and rides, moorland, or coastal dunes and under-cliffs. Better colonies might comprise a few hundred adults though the best sites may contain several thousand.

Once they have warmed up male DGFs are restless and elegant flyers, spending much of every sunny day on the wing scanning their environs for females. The latter remain hidden low down in tussocky grass for much of their own time, and so may be located on scent. Mating then occurs in cover (pictured below), after which the females maintain a low profile until their eggs ripen and laying can begin on the Violet food plants. The eggs hatch two to three weeks later, after which the caterpillars immediately hibernate, re-emerging the following spring.

Mating pair

Mating pair

Climbing back to the top of Bald Hill I at least doubled my morning’s tally of DGF and that was the most productive area. But by 11 am conditions had become lightly overcast and having warmed up sufficiently already the flying males were far less prone to settle when active. So I resolved to return on another fair weather day and start in this location to enjoy a second course of this Fritillary feast.

As in the past I found my second site of choice for this season to be one of the less visited areas of the Aston Rowant complex, and on this day at least especially uplifting spiritually. In my experience most general public does not stray too far from parking areas and is certainly less inclined to clamber around steep chalk hillsides than butterfly enthusiasts. When I walked through one of the car parks to reach where I had left my own car it was bursting with vehicles and people, but where they might all be heading I could not tell. It had been a simply superb Sunday morning here.

Dark Green Fritillaries and friends

I did indeed return two days later on 9th, but in hazy sunshine DGFs were less active in the area I most wanted to re-scrutinise at the top of the hill. Hence I ended up doing another full circuit of the site, gaining personal first records here of Adonis Blue and also finding my first Small Skippers of the season. As the sun came out fully I reached one of the Thistle patches featured above and three butterflies were again nectaring. So even more pictures were taken as these bravura butterflies put on an encore performance.

Dark Green Fritillary

Dark Green Fritillary

I can rarely remember one butterfly species producing as many images of the quality I seek as Dark Green Fritillary over these two days on the Chiltern escarpment. A celebration indeed.

Having gone into 2020 with a specific wildlife agenda the spring part of which is now on hold for another year, on the first day of summer I was able to get out and convert one item of it. This is the earliest date on which the mystical and fabled aurantiaca, the teneral female Scarce Blue-tailed Damselfly was recorded in 2019 by one of the leading British odo bloggers.

Today was my own third attempt at experiencing the quite beautiful, orange and black-toned colour form in what is a brief window of opportunity. A year ago I had to abandon my search in overcast conditions, and in 2018 I just didn’t see any. Thus it was that at around 11am I came back to one of my favourite New Forest odo sites, Latchmore Brook (SU182124). The parking area was by necessity closed and walking in from a discreet distance to respect appeals from local residents I felt pleased there would be rather less general public than usual here.

Scarce Blue-tailed Damselfly, imm fem aurantiaca phase

Scarce Blue-tailed Damselfy (SBT) has a marked preference for shallow water conditions with little vegetation, that occur in heathland valley mires such as one to the immediate north of Latchmore Brook. I was concerned that after such an exceptionally hot and dry May the bog here might have dried out, but on arrival found plenty of surface water (pictured below). After walking about at random for a while I waded into what seemed from past experience of the site a promising looking piece of mire. Then on turning around to keep my footing, there right behind me was an aurantiaca in all her bright finery. What a moment!

Lowland valley mire habitat at Latchmore Brook

Normally I am perhaps too sensitive over going into odo sites and possibly damaging habitat. But here the mire was already greatly pitted and trampled by grazing cattle and ponies, so I did not feel my usual compunction at doing more of the same. Indeed a degree of such habitat disturbance creates favourable conditions for SBT (per Brooks and Lewington). I was surprised by how still my quest kept for much of the time as I captured the images herein, so she was not bothered by my presence. She really is a rather special damsel, is she not?

Scarce Blue-tailed Damselfly, imm fem aurantiaca phase

The same degree of tolerance was not evident from the human company today. Another odo hunter on site ignored me studiously through an hour before the blogger himself arrived and blanked me too, not for the first time in the field. But I had already self-found my quest, and not one for being rabbited at myself never attempt to make others engage if they do not wish to. I sought out more aurantiacae through a further hour or so here but without success. Mission had been accomplished early on this visit.

SBT’s emergence period typically begins in late May, peaks in June and continues through to July. Emergence occurs throughout the morning under favourable conditions, so my own timing seemed to be appropriate. But when delayed by cooler, overcast conditions a sudden sunny spell will trigger activity at other times of day. Freshly emerged adults, of which I noticed some here are dull brown but develop brighter colours by the following day. Females progress from this initial bright orange phase to greenish brown as they mature. The flight season lasts until early September.

Scarce Blue-tailed Damselfly (imm fem)

Scarce Blue-tailed Damselfly (imm fem)

I possibly owed success today to the relative shallowness of the mire in the present prolonged dry weather period. On past visits here I can recall misplaced steps causing me to sink in to knee level and so would have been far more cautious, but today there were no such mishaps. I doubt whether odo royalty secures its images by always staying on the perimeter. Having gained these pictures so early I wondered what to do next and the best answer seemed to be secure an acceptable one of a male. I located several moving low down in the mire vegetation, of which only this study (below) adequately shows the diagnostics.

Male Scarce Blue-tailed Damselfly

First impressions are of a smaller, weaker flying blue damselfly than regular Blue-tailed. The “blue tail” itself extends over the lower part of segment 8 and there are two black dots on segment 9 that are just about discernible in the above image. Markings on the thorax develop through green and turquoise to deep blue as males mature. They spend their time lying in wait for passing females, being quick to investigate then pursue any likely mate.

Scarce Blue-tailed Damselfly, imm fem aurantiaca phase

But today was all about the female Scarce Blue-tailed Dameslfly. There is very little for me still to experience where English odonata are concerned. To have now successfully searched out this highly attractive colour form after two years of trying was immensely satisfying.