www.ukbutterflies.co.uk

That White Admiral is remarkably early, their appearance signals the start of Summer mayhem.

Long may it last !.
Trevor.

I was hoping to see a White Admiral at Fermyn Woods in July Neil when I go looking for the PE, do think they'll still be there Goldie

'Return Of The Small Pearls' Walk

I was slightly apprehensive about today's (9 June) 'Return of the Small Pearls' walk at the BC Park Corner Heath & Rowland Wood reserves, as my reconnaissance visit of yesterday suggested that the Small Pearl-bordered Fritillary (SPBF) flight season was in its late stages, and that we were unlikely to see any freshly emerged butterflies.

How wrong I was; this turned out to be one of the most enjoyable walks I've ever led, perhaps because of the unexpected delights on offer, and also because the results confirmed my long-held belief that this reintroduction has gone very well indeed. It certainly helped that we had an unusually large crowd (48) of very appreciative people. They were very generous too and we received a fantastic £84 of donations at the end of the walk, which will go straight into our conservation pot.

Success came quickly and our guests were soon calling out "another one here" as we discovered plenty of SPBF in the first area (rush meadow) we searched, including some recently hatched females. We saw many other species too, the highlights of which were early examples of Ringlet and White Admiral. But the walk was really about the Small Pearls, which put on a fabulous show for us as we wandered around the rides and glades of Rowland Wood.

The tally increased further when we visited Park Corner Heath, seeing more SPBF, both females and males, in excellent condition. The star of the show was a dark aberrant female fritillary, which provided a wonderful grand finale as she posed beautifully between frenetic bouts of egg-laying. A quick look at my score sheet initially suggested we had seen 18 individuals, but closer scrutiny of my notes later gave me a total of 20. A few more were seen after the walk, in previously unvisited areas. There is clearly life left in the SPBF season. Thanks to everyone who came along; it was great to see so many smiling faces of all ages.

Great to hear how much of a success the reintroduction has been Neil That smoky female is a stunner

Have a goodun

Wurzel

Neil Hulme wrote: ...The star of the show was a dark aberrant female fritillary, which provided a wonderful grand finale as she posed beautifully between frenetic bouts of egg-laying..

I believe that was payback from above for all the work you've done for this species, Neil.

What a beautiful insect she is!

Black Hairstreak Discovered In Sussex

David Cook has discovered a large population of Black Hairstreak in Sussex, at the Ditchling Common Country Park. This species has never occurred naturally in Sussex, being restricted to the clays running between Oxford and Peterborough, but a very large group of colonies developed in Surrey during the second half of the 20th century, following a 1952 introduction (much of the habitat was ultimately destroyed).

Following the sighting of three elderly, late season specimens last summer, a survey has been underway this June to determine the significance of these sightings and the status of the species locally. The presence of a large population (maximum day counts up to 98) has now been confirmed, extending over at least 1.3km of suitable habitat at Ditchling. The species may have spread to other areas within this landscape.

The history of the Surrey introduction indicates that the spread of even large, healthy populations may be a very slow process, moving at only c.1km per decade (Thomas & Lewington 2014). The size and spread of the Ditchling population suggest that it was established long ago.

It is entirely feasible that this species has remained undetected for a long while, due to its very small size and unobtrusive appearance, elusive habits, short flight season and the typical pattern of boom-and-bust which renders it almost invisible in some years, even on the best sites. This year the species has appeared in unprecedented numbers across its natural homeland, probably reflecting the advantageous conditions for larval and pupal development through May.

The male butterflies are using English Oak as ‘Master Trees’ and both sexes descend to sit on Bracken, both to sunbathe and feed on honeydew. Although the condition of the males deteriorates rapidly, many females (slightly larger and more orange-brown on the underside) are still hatching and a patient search should reveal these.

The best area to observe the species is the corridor of Blackthorn centred on TQ33441813, but the butterfly can be found on almost every suitable stand of the plant within the country park.

Congratulations to David on making such a momentous discovery. We are pleased to announce that Sussex has a new resident species; the Black Hairstreak is here to stay.

Notes:

The Black Hairstreak is protected under Schedule 5 of the Wildlife and Countryside Act 1981 (for sale only).

Ditchling Common is a Site of Special Scientific Interest (SSSI), notified as such in 1986; it is illegal to introduce species to a SSSI (once designated as such) and illegal to collect on a SSSI without consent from Natural England.

It is highly recommended that releases of all-but-common species (back to the site from which early life cycle stages may have been collected for educational purposes or scientific study) conform to the ‘BC Code on Introductions and Re-introductions 2010’.

Please report any sightings of this species away from the confines of the Ditchling Common CP.

I hope people are also looking at one of the last Surrey sites on the Downs Link track just up from the Sussex/Surrey border, if it has hung on in that area, it should show up this year.

That has to be one of the most amazing discoveries of the decade! Thanks for writing this up, Neil, and the very sensible advice regarding introductions!

Cheers,

- Pete

Beautiful images of a lovely butterfly, Neil. What an incredible find - well done to Dave for the discovery. Worth a supplement to the Atlas!

Dave

Yes, brilliant find. Amazing that it had remained undiscovered for such a long time though, in most years, numbers would have been very low.

Amazing stuff, even more so as mentioned above that it has remained undetected for so long. If only I'd known last week I'd have added that to my long day out last Wednesday!

There has been the suggestion that the "native" population in the Midlands in fact results from an introduction 200 or more years ago. This population is significantly isolated from the nearest other ones in mainland Europe. I heard the name Rothschild mentioned, the family having originated in Germany.

I can't quite recall where that suggestion came from but I think it was an elderly retired teacherfrom Oundle School who was chatting with us Black Hairstreak watchers some years ago in Glapthorne Cow Pasture, Northants.

Mssrs Rothschild and Cribb are probably having a good laugh at us at this very moment

Jack

I have to wonder what else might be hiding out there?

I had always thought that the declaration of the extinction of the Large Blue was hasty.

It had never been an abundant species but I do wonder whether it might not have lingered in [albeit] small numbers in some remote valley in North Cornwall or North Devon or more likely, on inaccessible cliffs.

Jack

Great news Neil.
Are we now to expect a 2nd edition of your book?

This is an amazing find and only just down the road from me!

There has been the suggestion that the "native" population in the Midlands in fact results from an introduction 200 or more years ago. This population is significantly isolated from the nearest other ones in mainland Europe. I heard the name Rothschild mentioned, the family having originated in Germany.

I have often wondered why the distribution of the Black Hairstreak in England is so limited, and Jack's suggestion has a ring of truth to it, although we will never know for sure. Another explanation is the underlying geology, because all the known colonies (up to now) are along the outcrop of Oxford Clay that runs south-west to north-east from Oxford to Peterborough. Is it something in the soil that the butterfly needs? Interestingly, Ditchling Common is on Wealden Clay, which is from roughly the same geological age and is similar in composition. Maybe the new colony has a good chance of dispersing east and west along the line of this particular rock formation? I hope so!

Some species are of course dependent on the geology – Adonis and Chalkhill Blues for example. But that is because the larval foodplant Horseshoe Vetch will only grow on chalk and limestone (I add "naturally" as Horseshoe Vetch makes a splendid rockery plant).

But I cannot see how that argument with respect to Black Hairstreak can apply to certain clays: the foodplant sloe is widespread across many types of soil.

I suggest that the clue to the restrixted distribution lies in the slow natural dispersal rate of the Black Hairstreak quoted as being only c.1km per decade – at that rate it won’t reach north Scotland for some 600 decades = 6,000 years.

Right or wrong, perhaps the simplest explanation for the Black Hairstreak’s distribution is human activity. That might be deliberate introductions or perhaps by farming activities (moving harvested crops, livestock, etc).

We’ll probably never know.

I might put my Butterflies of Sussex on e-bay as it is – as already mentioned – out of date

Jack

Andy Wilson wrote:I have often wondered why the distribution of the Black Hairstreak in England is so limited, and Jack's suggestion has a ring of truth to it, although we will never know for sure.

Yes, it has a highly curious distribution, and one is prone to question why it is restricted to a small strip of terrain in the middle of England (Sussex apart!!)

In France, the butterfly occurs quite widely, although it is localised in those areas where it is present. A comparison of the two distribution maps does raise questions about this species' range over here:

http://diatheo.weebly.com/satyrium-pruni.html

It is a pretty considerable distance from the Rothschilds' estate at Barnwell Wold to the south-western extremity of the species' range near Uffington, and surely it would not have covered the distance given its slow rate of dispersal? I believe the first British records (1830s?) predate the Rothschilds' interest in butterflies, as well.

There is a history of Black Hairstreak records from Worcestershire (Ent. Rec 102, pp. 253-4) as well as vague old ones for Shropshire and Monmouthshire.

Thanks, all, for your comments. With monitoring, surveying and conservation work currently running at such an intensive level, on top of outings purely for pleasure, I won't have time to respond individually for a while. The imminent Purple Emperor season isn't going to help matters!
BWs, Neil

Hairstreak Heaven

I've been very busy mapping the distribution of the now famous Black Hairstreak population of Ditchling Common, finding the species in all suitable habitat as far north as Janes Lane, about 1.3km north of where David Cook first discovered it. Here are some of my favourite images collected along the way (6 - 11 June).