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.

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.

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.

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.

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 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.

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.

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.

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.