Tuesday 25th February 2013

Butterflies of the Cranberry Bogs

Following the first really spring-like day here in the Netherlands, I realise that I must hurry on to complete my hypothetical butterfly list for 2013, in which I am adding those species that I should have seen to those that I actually found. My total list came to 77 species, but after that I “added” another five, bringing me to an imaginary total of 82 when I wrote my last diary entry.

Today’s post concerns two butterflies that are relics of the last Ice Age, and which are more at home in Scandinavia, but which just survive in a few tiny, isolated bogs in the province of Drenthe, in the north-east of the Netherlands. Here, creeping over the sphagnum moss in these swampy areas, the extraordinary, stringy plants of Cranberry, Vaccinium oxycoccos, can be found, and it is on this diminutive plant that these two butterflies depend, namely the Cranberry Fritillary, Boloria aquilonaris, and the Cranberry Blue, Vacciniina optilete.

The tiny flowers of Cranberry, larval foodplant of both butterflies

Although I have seen both in previous years, in 2013 I failed to make the journey north to their specialised habitat during their short flight season in June/early July, although I did visit an area in the east of Belgium, where the Fritillary does occur but the Blue does not, as well as a reserve just over the border into France where the Fritillary certainly occurred until recently, but I failed to see it in either place.

Former Cranberry Fritillary habitat which is becoming overgrown

On one occasion when I visited the minuscule bog that I know in Drenthe that still harbours the Cranberry Fritillary, I happened to be holding the butterfly book open at the page with the illustration of the butterfly on it…and one actually landed next to its own image in the book!

A Cranberry Fritillary next to its own image in the book

Cranberry Fritillary, Boloria aquilonaris

The Cranberry Fritillary next to its own distribution map

Much effort has been made to try to link the few remaining bogs in which the butterfly occurs by cutting trees and creating corridors along which the adult butterflies could fly, but with little success, and it now looks as though the species’ outposts in the Netherlands may be doomed. The populations on the high plateaux in eastern Belgium are doing marginally better, but even their future hardly looks secure. However, luckily the species is widespread in Scandinavia, so it is not in immediate danger overall.

The same holds true for the Cranberry Blue, Vacciniina optilete, and its Dutch populations are equally endangered. I tend to see this attractive species in an area of bogland bordered by a low ridge that is covered with Juniper and Crowberry, from which it is possible to spot the rather dark, almost purplish adults fluttering over the wetter ground below.

Cranberry Blue, Plebejus optilete

A male Cranberry Blue showing the dull, purplish blue upperside

Like the Fritillary, the Cranberry Blue is common in Scandinavia, and I have seen many in southern Norway. Here the butterfly may be seen in a wider range of habitats, including rocky moorland.

Cranberry Blue, Plebejus optilete

A Cranberry Blue in southern Norway, where it is much commoner than in the Netherlands

Had I seen these two boreal bogland specialists, plus the five species already mentioned, my 2013 list would have reached: 84 species

nextpost

Saturday 15th February 2014

Grote Vuurvlinder…the great fire butterfly…or Large Copper in English

Continuing with my eccentric plan of adding the butterfly species that I did NOT see within my regular hunting grounds last year to the 77 that I did manage to find, and having “added” Large Tortoiseshell, Mallow Skipper, Woodland Ringlet and Green-underside Blue, the next species, chronologically speaking, is the magnificent Large Copper, Lycaena dispar.

This butterfly has an almost mythical significance for British butterfly enthusiasts. Originally distributed through the fenlands of East Anglia and around The Wash, as well as possibly in the Somerset Levels and in Gloucestershire, the butterfly finally fell victim to the drainage efforts of the Dutch engineers, followed by the depredations of voracious collectors, and the last true British specimen was caught in 1851, finally putting an end to the British subspecies of the Large Copper, Lycaena dispar dispar.

On the continent, the species has fared somewhat better, with the subspecies L. dispar rutilus having a disjointed distribution including the Garonne around Bordeaux (where I have seen it), north-eastern France (where I have had outstanding encounters with it in both Lorraine and Alsace), and then across eastern Europe (including the Hortobágy, in Hungary, where I saw it in considerable numbers).

Large Copper, Lycaena dispar rutilus Large Copper, Lycaena dispar rutilus

The above two pictures were taken in the Hortobágy national park, Hungary, in July 2010

This subspecies is considerably smaller than the original British dispar, and differs from it also in having two generations per year, where the British subspecies had only one, from mid-July to mid-August.

Large Copper, Lycaena dispar rutilus Large Copper, Lycaena dispar rutilus Large Copper, Lycaena dispar rutilus

These three splendid Large Coppers were photographed in NE France in May 2005.

The third subspecies, and an almost identical one to the original British Large Copper, is Lycaena dispar batavus, which is restricted to one large mosaic of marshland habitats in the provinces of Overijssel and Friesland, in the Netherlands, and which also has only one generation per year. Subspecies batavus was first described in 1920 by my great grandfather G C Champion’s close friend Charles Oberthür, a renowned French entomologist from Rennes.

Large Copper, Lycaena dispar ssp batavus

A Dutch Large Copper, photographed in De Wieden in July 2006.

During my 2013 butterfly-watching, I had neither the chance to visit Lorraine between late-May and mid-July nor between mid-August and mid-September to look for ssp rutilus, nor did I have an opportunity to visit the last stronghold of the single-brooded Dutch ssp batavus between mid-July and late August (when I am usually at home in Scotland). Even if one does manage to reach the national park of De Wieden – De Weerribben in optimal weather conditions within the flight season, there is no guarantee of finding the butterfly in this extensive area of marshland, lakes and reedbeds. The males hold large territories and occur at very low densities, so finding them is hard. However, in two previous summers I have had the privilege of approaching this elusive jewel of the marshlands, and have enjoyed unparalleled views of both males and females nectaring on waterside Purple Loosestrife flowerheads.

Large Copper, Lycaena dispar ssp batavus

This final picture, of a Dutch Large Copper peeping round from behind an unopened Purple Loosestrife flower spike, is perhaps my favourite of all the butterfly photographs I have ever taken. The butterfly looks so coy!

Had I seen either of the two subspecies of Large Copper, plus the four previously mentioned absentees from my 2013 list, my total would have been: 82 species

nextpost

Friday 14th February 2014 (2)

A missed Spring jewel

On this wild, stormy winter’s night, with the rain lashing down and the wind whistling around my roof, the last thing I would normally think of would be butterflies, those jewels of the summer meadows. Yet I am now returning to my original plan of presenting those butterfly species which I did NOT manage to see last year, but which I would normally have expected to be able to find on my usual stamping grounds in the Netherlands, Belgium, northern France and westernmost Germany.

My final total for 2013 within this area, plus a short spell in Scotland, came to 77 species. I then started this project of discussing the extra species I should have seen, and by the time I wrote my last post on 13th January, I had “added” Large Tortoiseshell (78), Mallow Skipper (79) and Woodland Ringlet (80) to my imaginary list!

The next species I failed to see, chronologically speaking, was the Green-underside Blue, Glaucopsyche alexis. The only place I know within my regular area is the wonderful military camps in the northern Champagne region of France, an absolute oasis of biodiversity amid a sea of intensive agriculture in which hardly a butterfly can survive. Long may the French Army continue to require these chalky areas, preventing the cereal farmers from ploughing up the flower-rich natural grasslands and converting them into vast swathes of rapeseed or grain.

Green-underside Blue, Glaucopsyche alexis

The Green-underside Blue has a short flight season, from late April till mid-June, and as the weather was cold and grey through much of this period, and the few warm, sunny days did not coincide with any weekends when I could possibly have visited, it is perhaps hardly surprising that I missed this beautiful butterfly, which can easily be identified by the fact that the black spots on the underside are far larger on the forewing than those on the hindwing.

Green-underside Blue, Glaucopsyche alexis Green-underside Blue, Glaucopsyche alexis

Had I seen Large Tortoiseshell, Mallow Skipper, Woodland Ringlet and Green-underside Blue, my 2013 total would have been: 81 species