Monday, 24 April 2017

Larval Doings


After moaning in various forms about the hard time that winter represents for most butterfliers, I’ve now encountered another period of lean pickings, the March – April gap, when the first hibernators appear in early March, injecting the first rays of spring-like hope into the year, before promptly it is promptly removed as the next cold front rolls in from the West. This time of year is arguably more fraught than winter, winter at least brings with it the comforting certainty that there are no butterflies to see, no precious moments of summer to snatch, but in the March – April gap, you can’t help but feel you should be doing more to seek out those first Orange Tips (this is of course foolish, the first Orange Tips always find you), and so it is that a new season of frustration is born.

To combat this, like winter, I have developed a daring strategy to combat this, turning to those shadowy brethren, the immature stages, this year, those orange sports-car butterflies – the Fritillaries.

Somerset is not as blessed with Fritillaries as perhaps it should be, High Brown was last seen at Hurlstone Point in about 2000, victim of extremely challenging terrain for management, and a lack of resources, and Pearl – Bordered Fritillary on Exmoor, up at Mounsey in 1992, whilst Marsh Frit is on the ropes, maintaining a transient presence up on Exmoor, and it would seem, hiding out elsewhere, with the exciting report of a larval web in East Somerset this spring, it remains to be seen if they will re-appear at Ash Priors this spring (fingers and toes firmly crossed).

A 4th instar Heath Fritillary Larva at Haddon Hill - 21/03
Despite this, it’s not all doom and gloom, indeed, one of our trademark species is a Fritillary – the Heath Fritillary. This shouldn’t really be a trademark, a rarity, since it was once a common enough species to earn its own nickname – ‘The Woodman’s Friend’, thanks to its dependence on managed woodland, where it breeds in areas of coppice, typically peaking 2-4 years after coppicing and then tailing off and having to move on to new areas. In coppiced woodland Heath Frits breed on Cow Wheat, laying eggs in small batches (averaging about 40) on and around the foodplant, typically growing in sunnier areas, often over bare ground. The key here – open coppice, sunny spots, reflective bare ground is heat – this butterfly is one of some that like it hot, and can’t survive without it, and so the rapid decline in coppicing sounded the death knell for most of its populations at the turn of the 20th century, leaving it isolated in Kent (the East Blean Woods complex), and on the Devon-Cornwall Border. This meant then, that its re-discovery on Exmoor on 1984 was one of the great butterflying events of the last century, up there with Fort William’s Chequered Skippers, when strong colonies were found completely defying convention and flying between 200-400m (no other British colonies are above 100m) on moorland edges – they make ‘em hard in Somerset. This was at a time when the loss of the Large Blue had galvanised conservationists, and intensive study by Martin Warren, and some timely management changes ensured its future, though not before a rocky period on Exmoor in the 90s. Now it flies in quite a few areas on Exmoor, and most of its old 70s haunts, as well as several Essex re-introduction sites. Interestingly, its foodplants at the Devon and Cornwall sites (where it flies in old hay meadows and railway cuttings) are Germander Speedwell and Ribwort Plantain – this catholic foodplant choice seems to preclude rarity, but it underlines the key point about Heath Frits – it is the quality of the foodplant, the heat, that is key.


Nowadays a future for this butterfly in our fair isle looks relatively assured (though recent UKBMS results indicate it has declined by 82% over the last decade), with BC’s Two Moors butterfly project just finished, and currently its All the Moor project helping it along on Exmoor (with lots of great management by the National Trust’s Holnicote estate), and I’m lucky enough to have a thriving colony up the road at Haddon Hill, and so it was that I paid them a visit on the 21st of March. The larvae hatch from their egg batches after a couple of weeks, and feed companionably together in a small web before dispersing in their second instar, and in September, in their third instar, spinning up the edges of dead leaves near the ground and moulting into their fourth instar and going into diapause. They emerge, phoenix-like the following year, basking on dead leaves as their foodplant germinates around them, often in friendly little groups. These larvae were my target on my visit, and after about 20 minutes searching, I struck gold, 2 singletons, and a happy trio all in a small area of bilberry at the bottom of the slope where they fly (about 6 metres from the wood edge, so nice and sunny) where the Cow Wheat was just getting going. They were laid out on dead Birch leaves on the moss through which the plants were growing, on the edge of a trampled Pony track (providing a sheltered little ‘valley’ for them) – sheltered, sunny, like everything with the Heath Frits – it screams heat. These weren’t up to much, and didn’t move in the hour I watched them – living the good life evidently.
4th Instar Heath Frit larvae at Haddon Hill (21/03), singleton in the left circle, and trio in the right
note the warm dead leaves, relatively open bilberry growing through moss (where Cow Wheat is germinating)
and the small path (foreground) creating a sheltered little valley.


A single 4th Instar Heath Fritillary larva on the circled leaf - a warm, open mossy hollow, on 11/04 about 20 larvae were here.


 
Impressed by these spiny little creatures, I decided to return to see them in their magnificent final form (6th instar) later on, I made good on this on the 11th April and was glad I did, for a larval horde awaited, with 36 counted lounging about amongst the Cow Wheat in 45 minutes of not especially intensive searching/photography. When a caterpillar is so common you have to watch your feet, it is a butterfly unashamedly thriving – and it’s good to see. Once again they were all intent on getting warm, basking either on the moss through which the foodplant was germinating, or once more, the dead leaves. I think the key to my lucky strike probably had a lot to do with the area I searched, one of the most open patches of the site, with the largest quantity of these warm moss mats, as opposed to denser areas of bilberry where the cow-wheat is closed out and the ground shaded and things are less suitable for the larvae – heat, heat, heat! I haven’t yet decided what instar these larvae are – they look very similar to the fourth instar larvae of the month before, but with more white spotting (is this just more obvious because of their larger size?) – I’d be interested if someone knows.
 
 

A Heath Fritillary larval horde, the two on the right are on a small Cow Wheat seedling (you can see some nibbling to the left of the middle one) - where there is one, there are often more!
 
Heath Fritillary larva at Haddon Hill 11/04 - not too sure what instar
Heath Fritillary larva basking at Haddon Hill 11/04
 
This area had about 30 of the larvae I found - note how much more open and mossy it is than the surrounding area, at the bottom of the slope - sheltered and warm, Cow Wheat was germinating in large quantities.


The same area from the other side.
 
 
Heath Frits were not the only larval target this spring. More to follow!


















Friday, 17 March 2017

Alpine Amble - Part 3


After a reasonable attempt at spring the over the last few days that has seen me clock up all the 5 normal hibernators, the weather has turned and Lepidoptera once more seem a rather distant and frivolous summer thing, and as such, it’s time to burn the swiss midnight oil afresh.
 
BVW roosting.
 
The ‘Whites’ is a bit of an amorphous term that I tend to apply fairly freely to anything in the first 80 pages of Tolman & Lewington, hardly a monophyletic group, but convenient. This includes Swallowtails, Apollos, Festoons, Brimstones, Clouded Yellows, and then at some point actual whites. Over the course of the walk, we notched up 17 species in this fairly arbitrary group, with the commonest probably Black-Veined.
 

Acrobatic copulation from BVWs
Despite their relative abundance, I always find these butterflies strangely thrilling, a little piece of Old England flying by on their papery wings. Black-Veined Whites became extinct in the UK in the 1920s, with the failing of the last Kentish populations, a string of releases has followed since, famously by E. H. Newman in the grounds of Churchill’s Chartwell estate, and most recently, a clandestine introduction to Stockbridge Down resulting in trampling of some of the site’s key habitats by ardent photographers – a cautionary tale about the use of such releases if ever there was one. The causes of extinction are poorly known – Colin Pratt’s ‘Modern review of the Demise of A. crataegi L., the Black-Veined White’ notes a string of wet Septembers tended to precede extinctions on most sites, and the cries of many frustrated breeders of the time who suggested an increase in passerine populations (due to shotgun innovations=fewer raptors=more blue tits=more predation of larval webs and pupae). In essence, it’s far from an open and shut case.

Mountain Green-Veined White at roost.
 
Following the veined motif, Mountain Green-Veined Whites became one of the commonest butterflies at higher altitudes, and despite being very active in sunny conditions, were relatively easy to find and photograph when at roost on flowerheads. These differ from ‘our’ Green-Veined Whites by having heavier, greyish streaking, and often more of a dark suffusion. Interestingly, they have this in common with Scottish, thomsoni Green-Veined Whites – a nice bit of convergent evolution, adapting to their common struggle against frequent colder spells.
 
 

 
 
 
 
Having looked back through my photos from the trip, it’s clear I didn’t pay perhaps as much attention to the whites as I should have, with only a few photos of Mountain Clouded Yellows and their kin, probably because most of it was lavished on one particular set of broad white wings – Apollos. These are arguably one of Europe’s most impressive butterflies – ardent brits might choose the Purple Emperor for its dazzling iridescence, and aloof, regal nature, yet Apollos are amazing in a different kind of way: ethereal, seemingly detached, gliding past on wings so large and papery it’s possible to locate them as they soar past the back of your head, purely on the basis of the rustling they make as they move, and for such a butterfly, an iconic setting is a must, so snow-capped peaks and sound of music meadows it is – they, like most alpine butterflies, are a sight it’s hard not to be seriously impressed by.
 















Tuesday, 6 December 2016

Alpine Amble - Part 2

 
 


Searching for Brown Hairstreak eggs to stave off the winter blues is proving unsuccessful, with favoured thickets of young Blackthorn having been flailed left right and centre, so it’s back to Switzerland to eke out the remains of the summer that was. Unlike the lycaenids, the fritillaries didn’t yield any new species for me, but it was nice to re-acquaint myself with old friends in a different context. Fritillary is a vernacular name that doesn’t really reflect the taxonomy of the butterflies that it’s applied to, which can be divided into two main groups: Melitaeini (Euphydryas and Melitaea) and Argynnini (Argynnis, Issoria, Boloria, Brenthis in the Alps), 2 rather distantly-related groups of Nymphalids. Melitaeini are generally smaller, with the classic checkerboard markings, while the Argynnini are typically the larger, more orange, and more mobile species.


Glaciegenta
Glaciegenta
 
My favourite of the fritillaries is one of the Melitaeini, the Marsh Fritillary (Euphydryas aurinia). In the UK, it favours damp neutral/acid meadows and calciolous grassland, but in Europe is a bit more cosmopolitan, and has evolved into a large variety of regional subspecies, generally with a high altitude form, and low altitude form in each area. A new paper gives loads of really cool information on the taxonomy (and some pictures of the many awesome-looking forms): http://onlinelibrary.wiley.com/doi/10.1111/syen.12167/abstract , in Spain for example Euphydryas beckeri (or Euphydryas aurinia beckeri if you’re not a splitter) flies at low altitudes, while Euphydryas aurinia pyrenesdebilis favours the peaks, and in the South of France: Euphydryas aurinia provencalis in the lowlands, and Euphydryas aurinia glaciegenta in the Alps. The latter, formerly lumped with pyrenesdebilis as just debilis (on account of morphological similarities resulting from convergent evolution, the two are pretty different both in terms of genitalia and genetics apparently) was the subspecies I caught up with, a smaller, more contrasty form than the ones I know and love from the west country (Marsh Frits tend to get a bit smaller and darker with altitude). These stunning little beasts were toughing it out by one of our campsites at 2000m towards the end of the walk, they feed on gentians (unlike ours, which opt for Devil’s Bit Scabious), and fly much later in the year, between June and August depending, like many things in the Alps, on the altitude.
 
Mountain Fritillary (metallic female!)
Mountain Fritillary

 
Shepherd's Frit

 
Shepherd's Frit
 
 
A variety of other high Alpine species were flying alongside these at our campsite, including Shepherd’s Fritillaries, a species that looks very similar to the closely-related Mountain Fritillary (the males can be distinguished by greater red suffusion on the underside, and two rows of submarginal spots in Shepherd’s, and the females by Mountain’s gorgeous blue suffusion). Both are high altitude specialists feeding on violets, in common with most Boloria species, and fly extremely quickly in hot weather, fortunately I was able to catch up with a couple of them on cooler afternoons. These flew alongside their close, and equally similar-looking relatives, Small Pearl-Bordered and Pearl-Bordered Fritillaries, both are classic spring species here in the UK (apart from when Small Pearls sneak in a second brood and ruin everything in August), but with the high altitudes and cold temperatures in the Alps delaying development, I found many mud-puddling companionably alongside Silver-Spotted Skippers and Chalkhill Blues – the ultimate species of heady late summer days on the chalk back here, with the orange emperors of the spring woodlands and meadows – weird!
 


High Brown Fritillary (Note sex brands!)
Again note sex brands!
 
Niobe Frit egg-laying.
 
Other classic summer species flying alongside these early emergers were the Argynnis species, High Brown, Silver-Washed, Niobe and Dark Green Fritillaries (in order of increasing abundance). The latter were present in pretty much every flowery meadow, like lepidopteran sports cars, fast, flashy, and utterly unattainable, I’ve seen them every year for the last 6 and still haven’t got a photo that I actually like. I thought I’d succeeded with the photo below, but in an elated rush of blood to the head, I’d not noticed the enormous shiny sex-brands on the forewings that should have been screaming High Brown, this was only encountered a couple of times, both in the small, sheltered clearings that seem to be a key part of Alpine woodlands. Niobe was slightly commoner towards the end of our trip, quite distinctive in flight with its slightly paler ground colour and blue-looking veins (it’s the little things), it falls somewhere between Dark Green (very rounded) and High Brown (pretty angular) in terms of its shape, and was found in pretty similar habitat to the High Browns. Silver-Washed Fritillaries are the odd ones out of the group, discarding the ‘dots and pearls’ underside motif of their relatives in favour of their own magnificent green and white water colour. They’re more of a woodland butterfly too, and like High Brown, tended to pop up in clearings along the route. Interestingly, the ultimate Argynnis has just begun to stake a claim to Swiss territory (as chronicled on Guy Padfield’s UK Butterflies Diary here: http://www.ukbutterflies.co.uk/phpBB/viewtopic.php?f=29&t=4872&p=74964&hilit=Cardinal#p74964, this is of course, the legendary Cardinal, possibly the chief of all the European Fritillaries, a giant, roided up silver-washed with a green tint and extravagant red forewing panel just because, I was lucky enough to catch up with a couple in the south of France a few years ago (see photos).


Bonus pic of 'The Chief'
 

 
Tit Frit
Tit Frit

The commonest fritillary from the trip was undoubtedly Titania’s, this is a smart butterfly that tends to pop up hand in hand with Purple-Edged Coppers (since both feed on Bistort in damp meadows). Like most Bolorias, it’s a wonderfully graceful flyer, with interspersing rapid flapping with lengthy glides. Perhaps this is where it gets its name from, Titania, in Shakespeare’s Midsummer Night’s Dream was the Queen of the Fairies.
 
False Heath Frit
Knapweed Frit


 
In previous trips to the Alps, it’s always been joined by the Lesser Marbled Fritillaries (yet another Bistort feeder), yet these handmaidens to the queen were strangely absent in the parts of Switzerland that our walk took us to, instead, the second most abundant species was the False Heath Fritillary. As the name suggests, it’s a dead ringer for Heath Frits which we know and love from coppiced woodland in the UK, appearing slightly darker, the cause of the occasional identification headache. In fact, the whole Melitea genus becomes rather more varied and tricky once you go abroad, along our walk for example, we clocked up Spotted Fritillary (bright orange, and easy enough), Grisons Fritillary (another high-altitude hard nut, look for the dumbbell mark on the forewing), Meadow Fritillary (slightly sparser forewing markings than Heath and the darker False Heath), Heath Fritillary, and Knapweed Fritillary (like a large, angular Glanville Fritillary – very smart). Generally, I managed to pick my way through this group and the majority of the ID disasters were saved for Pyrgus (with a handful helpfully set aside for Erebia too, in the interests of fairness), such disasters (I’ve convinced myself), are a natural part of getting to grips with the awe-inspiring variety of butterflies in the Alps, and well worth the effort.
 
Tit Frit in the land of the Tit Frit

 

Saturday, 3 December 2016

Alpine Amble - Part 1

 

 
 
 




As Autumn draws to a close and the long nights draw in, times become hard for butterfly enthusiasts, you can eke out the rest of the season, and kid yourself there’s still life left with reckless November Red Admirals, or tired, morbid Speckled Woods, or distract yourself with birds and Brown Hairstreak eggs as a stop-gap before the first Orange Tips next April. Truly, winter is a trying time of year. This is oversimplifying the case a bit, since serious devotion and field skills improve our understanding of our butterflies’ winter doings more and more each year (check out Matthew Oates’ Purple Emperor larval doings: http://www.thepurpleempire.com/Resources/Emperor%20Season%20Without%20End.pdf, and Pete Eeles’ White Admiral ones: http://www.dispar.org/reference.php?id=120) , this is the great thing about butterflies, there’s always another layer of complexity and understanding to unlock.
The point is however, that there are fewer butterflies around, and coping strategies are therefore required, one such, is reminiscence. This July, by way of a light at the end of the examination tunnel, I spent three weeks hiking in Switzerland, along the Via Alpina’s Green route (http://www.via-alpina.org/en/page/246/the-green-trail), with a long-suffering friend. The idea is to walk from refuge to refuge across Switzerland (we used tents, more because of cost than any purist walking notions), on a rather challenging route, generally involving a 1000m ascent and corresponding descent each day. It’s a famously impressive part of the world, taking you through the Bernese Oberland, past chocolate box towns (think Murren), rushing waterfalls (think Reichenbach, of Sherlock Holmes fame), and of course, high alpine meadows rich in butterflies. 

 
High altitude meadows - land of the Gland'

 
Over the course of the trip, we chalked up somewhere in the region of 100 species, many flying in awe-inspiring abundance, in equally awe-inspiring settings. For me one of the most exciting groups are the lycaenids, seen in much greater diversity than here in the UK, they’re striking, obvious, and pose few of the ID challenges that Erebia and Pyrgus often raise. The most exciting for me was the Glandon Blue, a really hardcore species that ekes out a living flying among the peaks (we never saw one below 1700m) at low densities (wherever there were large numbers of puddling blues, there would only ever be one or two Glandons), and thus has eluded me for a while. They’re small, and nippy, and appear very dark in flight, but are stunning up close, with a really unusual set of diffuse underside markings.


Glandon in Glandon country.
Lady Glandon
 
A typically anti-social Glandon sneaking into the corner of a party
of puddlers.


Seemingly copying the Glandon Blue’s underside, but setting it off with a rather more extravagant upperside (at least in the males), the Alpine Blue was another denizen of (slightly less) high altitudes, and while flying at similarly low densities, it was rather more widespread. These were joined by another new species for me, the Cranberry Blue, seen only a couple of times around boggy areas where the foodplant (Vaccinium uliginosum in the Alps) grew.

 
Alpine Blue
Cranberry Blue


Even more tied to their foodplants were Geranium Arguses, invariably seen perched on or around the flowers of Meadow Cranesbill (don’t know why I never looked for eggs). Sharing a second name and perhaps an underside with the Geranium Arguses, (but little else) was the much rarer Silvery Argus, I was delighted to chance upon a single female in a boggy clearing.

 
 

Geranium Argus, strangely enough, on Geranium.
Silvery Argus - set apart by the delicate
pale blue wash


Mazarine Blues, despite no longer gracing the meadows of our fair isle, were one of the commonest blues, flying in small numbers pretty much everywhere, right up to about 1800m. Females depositing their sea-urchin like white eggs on clovers were seen several times, as well as a male harassing one still drying her wings.

Mazarine Blue

Mazarine Blue


Commoner still than Mazarine Blues, were Small Blues, which were fairly ubiquitous, forming their little leks in small hotspots, particularly at higher altitudes. Here, the foodplant, Kidney Vetch was found thriving on rocky soils, very frequently with their eggs peppered liberally among the flowerheads. They were particularly fond of mud-pudddling, and on several occasions, made the greatest possible sacrifice for this predilection, when a careless foot or quad-bike tire ploughed over the little aggregations that formed in damp spots. Rather more sinisterly, survivors did not seem to take the hint, and would often be seen feasting among (and even on) the corpses of their fallen companions, a stark reminder of the life and death struggle that confronts one of the most fragile-looking of European butterflies every day.
 


Small is beautiful
Feasting on the bodily fluids of spent comrades.
 
Like the Small Blues, male Coppers were often seen staking out territories in sheltered spots, one to each glade. These weren’t too well represented across the walk, with just Sooty, Purple-Edged and Scarce seen (Violet, Large and Purple-Shot can also be found in Switzerland). Sooty was the commonest, in pretty much every flowery habitat up to about 1800m, Purple-Edged was frequent in boggy areas in little colonies, and Scarce was strangely patchy – it was abundant towards the end of the walk, but completely absent elsewhere.
 

Scarce Copper (male)
Sooty Copper (male)

Classic eurydame-type male PEC - what it 'should' be.

The lack of quantity of copper species was certainly made up for by their quality, these are royalty among lycaenids, the Sooty Copper a black prince, smoky, somehow lighter and more wraith-like on their larger wings than the petulant, angry fireballs of their Scarce and Purple-Edged relatives. All three species feed on relatives of docks, and come in their own limited-edition forms in the Alps: subalpinus for Sooty (much darker than lowland forms, lacking orange on the underside), montanus for Scarce (males with a thicker black forewing, and females a tad washed out), and eurydame for Purple-Edged, males lacking the trademark purple upperside colouring, and females a uniform brown apart from darker cell spots, while both sexes lack any really yellow underside markings. The latter proved a real point of interest, I’ve only ever seen them in the Alps  - all smart eurydame specimens, and was expecting to see much more of the same, but some didn’t seem to have read Tolman and Lewington, with one male sporting really impressive purple markings, and plenty of females with a yellow flush on the forewing uppersides.
 
Hippothoe-type male PEC - note strong purple iridescence,
what it 'shouldn't' be.


Strongly-marked PEC underside, more
hippothoe like.
Variety, both within and between species is very much the order of the day in the rich tapestry of life that is the Swiss lepidoptera, and nowhere was this more obvious than at the large gatherings of mud-puddling lycaenids that formed on hot days. Blue wings, blue skies, and white peaks will live long in the memory.