Adonis Blue at Queendown

This afternoon was rather overcast and cool, and I arrived at Queendown Warren at about half past two, stating until just gone five. As I parked up at the island the prospects didn't look particularly promising but the first wildflower patch did have over a dozen Meadow Browns, so there was limited encouragement there. Then I came across three Brown Argus there, and so I thought things were looking up a little. The next flower patch had both Brown Argus and Common Blues in reasonable numbers, and so I moved down to the bottom of the slope and picked up more of the same.

Through the fence and along to the next flower patch closer to the far corner and I was coming across Chalkhill Blues as well, and then finally the Adonis Blue, concentrated in the far corner. Good numbers of Lycaenids by now, all tending to sun, nectar and roost. I was using ISO 200 and I was quite happy with the picture quality, particularly when I switched to AV mode to ensure a slightly better depth of field. However I always have to watch our for motion blurring, either camera or subject so I need to keep an eye on the exposure speed when in AV.

This was a photo of a Brown Argus, Aricia agestis, possibly a female, partly shielded by foliage.

I got some nice photos of the male Adonis Blues. I don't think I noticed any females - they are more difficult to spot!

This is an Adonis Blue head close-up showing something of the eye colouration, antennal insertion above the ye, forehead tuft and maxillary palps.

The Adonis Blue has undergone great population changes over the last few decades, as befits a butterfly with a single food plant with highly exacting environmental requirements at the northern extremity of its range! Populations crashed very badly in the 70s in the UK, said to be due to the terrific drought of '76 affecting its foodplant the Horseshoe Vetch - God bless Dennis Howell who finally ended it by getting appointed as Minister for Drought, at which point the heavens immediately opened, creating floods!

Perhaps we should be seeing butterflies as extremely flaky organisms, subject to regular extinction and recolonisation in a very highly dynamic system. If this is so, then we would probably have very few species in Great Britain compared to Europe.....well, do the maths as the Americans seem to almost continually say! And populations should have remarkable powers of recuperation - the Adonis Blue is not a great spreader, in fact one of the worst, but it is rather good at recuperation - one colony increased from less than 50 to 60,000 in five years! There is also a theory with some considerable degree of backup from DNA evidence, that the current British population only arrived from Europe in the 18th Century. Perhaps then butterflies are not really the organisms best suited to act as the environmental canaries in the mine, being rather over-responsive!

Future conservation measures might be more solidly focussed if we knew more of the ecology of the Horseshoe Vetch. I wonder if we could now encourage it to grow in more diverse parts of Queendown, where it was introduced by KWT in 2002, with a greater variety of soil depth. That might give more resilience to the Adonis Blue in different summers and with different grazing intensities. Then we may need to do something about its lack of mobility - carefully! It seems to be doing OK in Kent, partly because of the reintroductions at Queendown and Darland Banks.

There are some excellent websites including this one "Learn about Butterflies".

Queensdown Warren late in the day

Lots of Meadow Browns and Two Marbled White Butterflies between 4:30 and 7:30 this evening.

This is a Marbled White, Melanargia galathea. This is a female, recognisable by the yellowish tinge on the underside of the wings, the males are more monochrome black and white. There are only four functional legs in both males and females in the family of Brush-footed Butterflies, Nymphalidae, the Browns, subfamily Satyrinae, the front pair of legs being converted into a small pair of "brushes". Incidentally, the stem behind is an Agrimony, Agrimonia eupatorium, stem going to fruit, remarkably beautiful.

This is the peak month for this butterfly and they should be dropping their eggs over the potential grass larval food plants from around this weekend onwards. This is a typical pose for these butterflies in the afternoon, either on grasses or their nectar source flowers. In the morning they tend to rest with their wings spread to warm up, and for the rest of the day of course they are generally much more active. Unimproved tall grassland is their typical habitat, particularly chalk downland, but even small patches of verge with tall grass will sometimes support small colonies. The Marbled White is a strong flier and a good disperser, so should be fairly good at surviving in the patches of grassland still available on the North Downs, according to research in Belgium and Germany. However the more patches there are, the easier that survival should be.

The Butterfly appears to be spreading slowly North and has most likely recolonised most of Europe from different glacial refuges around the Mediterranean. North Africa and specifically the Maghreb may also have been involved. There are two sibling species, Melanargia galathea that is thought by some to have expanded back into Europe after the last glaciation from two separate refuges in Italy (Western population) and the Balkans (Eastern population) and Melanargia lachesis that is currently found only in Spain and Southern France. The species split itself may have occurred much earlier in the glacial/interglacial cycles, but the mutual interactions of the two species raise several interesting questions about competition, dispersal and evolution. It is interesting to note that the form known as ssp serena is distinguished as the form found in Britain, which derives from the Western population of Melanargia galathea and which must also be a founder effect at the time of the cutting of the land bridge.

The subspecies include serena in Britain, galathea in Europe and the South Urals, donsa in the Caucasus, satnia in the Caucasus major and minor, lucasi in North Arfrica, and tenebrosa.  However I know little about the rest of the species' populations spread across Asia as far east as Japan.

The high genetic diversity and the relatively strong differentiation of the four African populations sampled in a
comparatively limited area of the Atlas Mountains indicate that the most probable origin of the species Melanargia galathea is northern Africa, with its sibling species, M. lachesis, evolving in parallel in Iberia. Most probably, M. galathea colonised Europe first during the Eem (last before this one) interglacial, some 130 ky ago. Since M. lachesis must have existed on the Iberian peninsula during that period already, M. galathea should have reached Europe via Italy. The genetic differentiation to distinct groups in Europe most probably evolved during the following (most recent) Wu¨rm glacial period.

There is a lot of genetic diversity in Melanargia galathea, but this is well mixed within its habitat patches and amongst the wider populations, due to the species' movement ability. The genetic diversity may have arisen partly as founder effects of the small populations isolated in refugia at the time of previous, and in particular the last, glaciation. The species may now in theory require this continuing diversity and intermixing and may be vulnerable to further habitat isolation if the genetic diversity is consequently severely reduced.

The distribution on the chalk in Kent is primarily Eastern according to Thomas and Lewington, and admittedly these are the most Westerly ones that I have seen so far in this county. On the other hand I have seen them in good numbers at Oxford services, so its not all about latitude! Other observers in Kent have also seen numbers to the West, at Darland Banks, Borstal, Lullingstone and Cobham, so the distribution in Kent may have evened out a bit.

This on the other hand is a male, not so well focussed sadly, seen a few moments later on a Large Knapweed, Centaurea macrocephala, flower.

Red Fescue, Festuca rubra, is thought perhaps to be an essential larval food plant, and it picks up some toxins from a fungal infection of that plant, which are apparently carried through into the adult body. However the larvae do feed on a range of other grasses.

Queendown Warren

A late afternoon trip up to Queendown Warren produced good numbers of bumblebees and the common Brown butterflies, but was disappointing for Chalkhill and the other Blues.

Firstly were the Cuckoo Bumblebees, and here are two versions of Bombus vestalis or Bombus bohemicus, the first version with only one yellow thoracic band, and the second version with a thinner band in the middle of the abdomen.

Here is the first version. If it is Bombus vestalis, it is probably a fairly worn specimen, as the yellow patches are now quite small and indistinct. These are all the same bee. The wings look a little worn and tawdry, and not strikingly brown, although clearly brown tinged especially on the veins. This would all fit with a Bombus vestalis that has been around the block a couple of times.

Frustratingly once again I cannot tell for sure whether it is a male or a female! If I had to make a decision I would think it is a male vestalis in which the antennal segment A3 is much shorter than the A5, but I really cannot be certain. I think this only applies to males, and is well seen in one of the photos on http://www.bwars.com/index.php?q=bee/apidae/bombus-vestalis.

This is the second version, with a slight yellow band on the abdomen. Again these photos are all the same bee. In this individual I would have said that the wings are rather browner than the bee above.

Butterflies at Queendown Warren

I attended the course on Kentish butterflies with Steve Weeks at the Kent Wildlife Trust headquarters at Tyland Barn today, and in the afternoon we all went off to Queendown Warren to put our new-found identification skills into practice!

We got into the swing of things on the more familiar butterflies, checking out the differences between the Meadow Brown and the Gatekeeper, and the Green-veined White and the Small White respectively. Then we got some of the more specialist and rarer prizes on offer and the first species up was a Silver Spotted Skipper, Hesperia comma, one of the descendants of those re-introduced to the Warren after the grazing programme had been disrupted and the old colony there become extinct many years ago. The re-introductions used stock taken from Lydden Down and Temple Ewell nature reserves near Dover, with similar earlier (1997) re-introductions also made to Wye Downs and Burham Down. The re-introduction to Queendown took place about ten years ago and the colony seems to be thriving. they don't fly far from their home colonies, so they need help if they are to spread out to re-occupy more of their former range. Here's one of the results of their reproductive efforts!

and here is another individual from an angle that more clearly shows that this skipper gets its name!

This butterfly looks as though its enjoying the nectar it is sucking up from this knapweed flower-head! The average life-span of an individual is only about 6 days, so they deserve every treat they can get!

The males spend most of their lives watching out for females and the females, once mated, spend most of the time looking for exactly the right clump of Sheep's Fescue, Festuca ovina, to lay their eggs on, while trying to avoid further male attention while they do so. Described as rare in the National Red Data Book these small butterflies are a specific treat wherever their colonies are still found.

The second chalk downland speciality was the Chalkhill Blue, Polyommatus coridon, and there were quite a few nearer the foot of the hill where it was a bit moister and also more sheltered, fluttering around on the lusher patches of marjoram. these were light blue, with some grey edging to the wings and hatching on the white margins.

Scattered amongst the Chalkhill Blues were some Common Blues, Polyommatus icarus, some of them looking a little tatty. These were more overall lilac in colour on the uppersides, with no grey edging and no black hatching on the white edge of the wings.

And then there was the butterfly speciality of this internationally important site, the Adonis Blue, Polyommatus bellargus, and here is a good one I saw just as we all left the reserve main bank at the top of the hill: