Monday 30th June 2014

The Cranberries

Following my ultimately successful search for the elusive Poplar Admiral, Limenitis populi, last weekend, I managed to squeeze in a brief visit to the coastal dunes that run along the Dutch coast. Here I was pleased to find several Niobe Fritillaries, Argynnis niobe. This species now appears to have disappeared from the inland Veluwe region of the Netherlands, but numbers in the dunes seem to be stable. They require areas of low, spreading bramble plants, among which they are relatively easy to find – but NOT to photograph, as they speed off immediately they are approached.

The only picture of the flighty Niobe Fritillaries I managed to obtain

On Sunday, the (virtually) annual pilgrimage northwards into the provinces of Drenthe and Friesland took place, with the aim of finding three rare species that are exclusively found in boggy areas, and all of which have undergone a massive decline and contraction in range in recent years. All of them are now only just hanging on the Netherlands. They may indeed become extinct as the climate warms, as they are all three “Boreal” species that thrive in the cooler climates of Scandinavia and northern Russia.

The first to be searched for was the rarest of the three, the Cranberry Fritillary, Boloria aquilonaris. This fast-flying species is restricted to just a few tiny, isolated bogs in the north-east of the country, and I only know one reliable site – and I knew my prospects would be even lower when I saw that a new No Entry sign had been placed next to the spot since my last visit to this minuscule bog, which harbours both the butterfly’s larval foodplant, the Cranberry, Vaccinium oxycoccus, and its favourite nectar source, the Cross-leaved Heath, Erica tetralix.

Luckily it was permitted to enter the adjacent forest track, and I managed to work my way around behind the bog, to a vantage point from which I could scan the area with binoculars. At first I was somewhat doubtful as to whether I would see anything at all, as the sun had disappeared some large clouds and only appeared briefly, and even then not remaining out for long enough to warm the place up.

Finally, after a few false alarms caused by several Large Skippers, Ochlodes venatus, whose gingery colour resembles that of the fritillary, although the size is of course quite different, I managed to locate a single Cranberry Fritillary, which I was able to watch for several minutes as it buried its proboscis into the Cross-leaved Heath flowers. No photograph could be obtained, but luckily I had photographed it well at this site in previous years – including one famous occasion when a Cranberry Fritillary landed on “its” page in my open butterfly book!

A Cranberry Fritillary I photographed here in 2005

In previous years, when it was still possible to plunge about in that bog, I had seen up to five individuals, but at least this one was better than none, and provided confirmation that the species is at least just holding on. I am glad that entry has been banned, as the site is highly sensitive to trampling…and I know from bitter experience that some photographers will stop at nothing to obtain that definitive shot of a butterfly species, while not even giving a thought to the fact that their own actions are hastening its demise.

The next species required only a short drive and a walk, but the weather was looking distinctly threatening by this time, and indeed it started to rain, and a thunder storm was raging not far away.

Despite these adverse circumstances, it was not long before I managed to spot a single female Silver-studded Blue, Plebejus argus, which later dropped down into the heather when I approached to photograph it.

The heavily pregnant Silver-studded Blue

Once the rain had subsided, a few brief gleams of sunshine encouraged me to press on to a juniper-covered slope, from which it was possible to scan the extremely boggy ground below, which was again a favoured haunt of the diminutive and inconspicuous Cranberry plant, which creeps over the sphagnum moss, unnoticed by anyone but the most careful observer. It was not long before a small butterfly drew my attention, and a closer examination revealed it to be my second target species, the Cranberry Blue, Vacciniina (Plebejus) optilete.

The Cranberry Blue was almost as hard to photograph as the Niobe Fritillary!

Like the fritillary, this butterfly is now reduced to a few tiny colonies, perhaps numbering not more than ten individuals, where it just manages to hold on. In total, I managed to spot either two or three, but not more. However, this may have been due to the unfavourable weather conditions rather than lack of butterflies.

Much work is being carried out here, specifically for the butterflies and their associated bog-land specialist species, mainly involving raising the water table, removing encroaching birch and pine trees, and linking the individual bogs to allow the butterflies to move from one site to another. We can only wait to see whether such measures prove to be effective, or whether they came too late to save a butterfly that may anyway be doomed as a Dutch species.

Habitat of the Cranberry Blue

The other wetland site I needed to visit required a drive of perhaps an hour to the north-west, to the impressive Fochteloërveen, an extensive protected area on the border between Drenthe and Friesland. As well now hosting a growing breeding population of Cranes, Grus grus, this wild, open expanse is home to the Netherlands’ last viable population of the Large Heath, Coenonympha tullia, which despite its overall rarity, can be numerous in some years here.

Former peat cuttings can clearly be seen on the Fochteloerveen

Although the clouds were closing in fast, there were still a few Ringlets, Aphantopus hyperanthus, and Large Skippers, Ochlodes venatus, as well as one unexpected addition to my 2014 list, a lone Gatekeeper, Pyronia tithonus. Luckily, just before the weather closed in altogether, I was able to spot one Large Heath dancing over the long, pale brown grass, thereby bringing my 2014 list up to 66 species.

One final bonus, once the butterflies had disappeared with the sun, was a splendid showing of Broad-leaved Marsh Orchid, Dactylorhiza majalis subsp. majalis, which were growing in disturbed ground along the cycle track that crosses the fen.

A fine group of Broad-leaved Marsh Orchids

Butterfly list as of 30th June 2014: 66 species

Saturday 28th June 2014

Butterfly of the Year!

Last weekend was mainly involved with socialising with friends near Bonn, but I did drop by the juniper hills of Alendorf briefly on the way, adding Meadow Brown, Maniola jurtina, Small Skipper, Thymelicus sylvestris, and Ringlet, Aphantopus hyperanthus, but it was the Purple-edged Copper, Lycaena hippothoe, that I was particularly anxious to find, and sure enough, despite the strong wind, it was not long before I found a single male, resplendent with his burnished copper and purple sheen. I had feared that I would miss this species this year, so this was a worthwhile sighting, and I savoured the experience of watching this male’s forays over the flower-filled meadow, always returning to approximately the same spot – male coppers are famously territorial, often pugnaciously seeing off much larger butterflies that venture into their domain.

The purple edges can clearly be seen on this male Purple-edged Copper

The male Purple-edged Copper

The underside of the Purple-edged Copper is also attractive

This weekend has involved a certain degree of frustration, perhaps because we are now in the kind of lull between the main flush of Spring butterflies and the first emergence of the Summer species. I did nonetheless manage to add White Admiral, Limenitis camilla, of which there were impressive numbers on the wing. This species is always a pleasure to observe, with its elegant, gliding flight, and to see so many was a real treat – at one point I had at least 15 in view at the same time!

This White Admiral has lost almost an entire hindwing

The grassland areas were awash with Marbled Whites, Melanargia galathea, another attractive species, which despite its name is not a White at all, but a Brown!

The Marbled White is in fact a Brown

Fritillaries were quite numerous, with one False Heath Fritillary, Melitaea diamina, turning up on a flower-head, despite the cold on Saturday. This attractive butterfly now seems to have disappeared entirely from the areas where I used to see it in considerable numbers in my usual haunts in the forest in northern France, but here, close to the Meuse, it seems to be holding on.

My one and only False Heath Fritillary (so far) this year

False Heath Fritillaries seem to love white flowers

Silver-washed Fritillaries, Argynnis paphia, perhaps the most impressive of all the fritillaries of this area, were already out in some considerable numbers, and it was wonderful to watch these bright tawny butterflies chasing each other over the bramble flowers.

Male Silver-washed Fritillaries are easily identified by the elongated dark marks along the veins on the forewing

Much smaller, but also attractive, Lesser Marbled Fritillaries, Brenthis ino, were also in evidence, easily identifiable by the chequered fringes to their wings.

This Lesser Marbled Fritillary was already looking rather less than fresh

One butterfly which I needed to see this weekend if I was to have it on my 2014 list was the Black Hairstreak, Satyrium pruni. Although elusive and hard to see, I know several patches of its larval foodplant, the Sloe, where it is normally to be found, but this time it took me a long while to locate this discreet little butterfly, but finally I found three individuals, feeding on Privet and Bramble flowers; I could easily have over-looked the first individual had it not been spiritedly chasing Meadow Browns away from its chosen flowers.

The elusive Black Hairstreak, its head buried in a bramble flower

But all these butterflies pale into insignificance as far as I am concerned, as today, after a determined search of potential haunts in southern Belgium and northern France, taking in Thursday afternoon, the whole of Friday, and much of today, I am able to report the sighting of perhaps the most impressive and elusive butterfly of the year so far, one that I have only seen on two occasions before, once in Sweden and once, on my birthday in 2011, here in this region, the Poplar Admiral, Limenitis populi.

This spectacular species, considered by some to be Europe’s largest butterfly, is a rare prize for me. It is seen every year in this region, but as it occurs only at very low densities in the vast forests that coat the hillsides hereabouts, and it remains almost exclusively high in the tops of trees, one’s chances of connecting with it during its remarkably short flight season are low.

I visited the exact spot where I had had the immense privilege to find a highly cooperative male Poplar Admiral on my birthday, 29th May, in 2011, but no sign of the butterfly this time. I returned on Friday, this time armed with a pungent mix of tinned mackerel juice and crème de cassis – the Poplar Admiral virtually never visits flowers, subsisting instead on honeydew exuded by aphids high in the treetops and on unsavoury items such as animal droppings and carrion. However, even this intoxicating mix had no effect, and by the end of a long Friday, I had virtually given up all hope of sighting this almost mythical species in 2014.

The male Poplar Admiral that appeared on my birthday in 2011

Nothing ventured, nothing gained, however, and one last attempt had to be made today, Sunday, and persistence indeed paid off. First, a probable male butterfly sailed over at high speed, but I was not quick enough to clinch its identity through the binoculars.

Later, while having lunch perched on a large rock close to a clearing surrounded by Aspen, Populus tremula, the foodplant of the caterpillars of the Poplar Admiral, suddenly a splendid black and white butterfly glided into view. Almost three times the size of its close relative the White Admiral, this was a brightly patterned female, complete with her broad white stripes, and I was able to follow her in my binoculars as she powered along, with typical admiral flap-flap-gliding flight, but she was not stopping, and headed right along the forest trail until she disappeared from view.

It is likely that Poplar Admirals are found, albeit at very low densities, throughout these vast forests, but due to their elusive habits, they are rarely seen. For me, however, this was almost certainly one of the highlights of my butterfly year, and a sight I shall remember for the rest of my days.

2014 total as of 22nd June: 62 species.

Saturday 7th June 2014

Violet Copper video:

The video below is a compilation of stills and video footage shot on 30th May in eastern Belgium: