www.ukbutterflies.co.uk

The false alarm over a possible Southern White Admiral in North Norfolk in October (I was able to photograph it – sadly it was a normal one) certainly got me thinking about what genuine colonists we might expect over the next few years.

Large Tortoiseshell might already have made it (there were apparently several sightings in the summer) but two mobile species that already occur in NW France are the Lesser Purple Emperor and the Poplar Admiral. Given then extraordinary elusiveness of our “ordinary” Purple Emperor and the great similarity of the Lesser, could the Lesser in fact be lurking undetected in some of our southern woods?

Other potential colonists? Over to you.

Jack Harrison

http://www.ukbutterflies.co.uk/phpBB2/v ... .php?t=791

Similar topic from a while back, Jack!

Hadn't see that but it does show that great minds think alike.

Jack

On the specific points you raise, Jack:

I am pretty sure the large tortoiseshell has never left Britain. I took this photo in the large tortoiseshell's Suffolk stronghold in 1985:



That was nearly a quarter of a century after the previous Suffolk record and I am sure it had been hanging in there all along. The experts said at the time that my insect was in too good nick to be a migrant (though it might have been an unpublished release, of course).

Having said that, I think the native stock has been supplemented with continental butterflies recently, that clearly have immigrated.

Lesser purple emperor is not the sort of thing to pass unnoticed. Everyone, from novice to world-weary expert, gets excited about emperors and watches them closely; and lesser PE really is very different from PE (especially form clytie, of course, which predominates everywhere I see them).

Southern white admiral would be very surprising in England - I associate this species with serious heat. Here in Switzerland, white admiral flies around my place in the mountains and southern flies in the Mediterranean climate of the Rhône Valley. I have never known them venture away from there.

As for poplar admiral, I think that is a very interesting proposition. The species is rare and elusive everywhere, but I have no idea why. The foodplant, aspen, grows widely (though poplar admirals won't take hybrid poplars and I believe this is a problem in some regions). It does fly around me, at 1300m, and so clearly doesn't have a thing about heat. So far as I know, the species has never been recorded in England but it is surprisingly easy to miss because it spends so much time in the canopy. I saw one in my local woods in 2006 and a second nearby in June 2007. I then searched daily throughout the rest of June and July 2007 and had one other distant sighting, which could have been a purple emperor.

This is the only picture of poplar admiral I got this year - taken from about 20 feet away during the 4 or 5 seconds it paused to rest. Massive, brilliant, fantastic butterflies. Would be a dream addition to the British list...



Guy

I agree that form clytie would be unmistakable but I have read that it doesn't occur in all populations of Lesser Purple Emperor. I am merely wondering if the normal form, badly seen partly hidden by oak leaves 10 metres above the ground, could easily be distinguished from the “large” PE? The guide books are probably not a good guide in this case; the two species do look remarkably similar in the books (except of course f clytie) but I have never seen in the flesh

Glad to hear that you think Large Tortoiseshell might never have disappeared after all. It's 60 years since I saw one!!!!

Jack Harrison

jackharr wrote:Glad to hear that you think Large Tortoiseshell might never have disappeared after all. It's 60 years since I saw one!!!!

60 years ago! That must be the great clouded yellow year of 1947!

Guy

One problem butterfly species already resident in northern France will encounter is that, whilst the warming climate might be beneficial to them, their numbers will already have been reduced, massively, on what they were (say) 150 years ago by habitat destruction. It is reasonable to ask why these species have not colonised already, as the number of potential immigrants/wanderers must be far less now than in the past.

In Britain, it is the 'wider countryside' species that are spreading north. The only 'wider countryside' potential colonist resident in northern France already that I can think of is the Map, which appears incapable of crossing the Channel.

I think the most likely candidate for natural colonisation is the Scarce Swallowtail, which is spreading north in France, seemingly finding that warming conditions more than offset habitat loss. As a dispersive species it could start turning up in southern England.

Perhaps more likely though is colonisation by accidental introduction - I could imagine a Large Tortoiseshell flying into the back of a lorry to hibernate somewhere in Germany and then emerging in southern England - or colonisation as the result of illegal releases.

I wonder if there will be some colonisations between southern Scotland and northern Ireland? Vagrant Commas have appeared in Ireland in the last couple of years, and both Small and Large Skippers have been spreading towards the areas of southern Scotland nearest to Ireland. And could Real's Wood White colonise Scotland? It is evidently capable of crossing the Irish Sea as it must have made the reverse journey to get to Ireland in the first place...

Indeed 1947 was the first year I saw Clouded Yellow (as an 8 year old). location extreme north of Suffolk (where the Large Tort seen in spring 1948)

Clouded Yellows encountered a few times over the years but not again in decent numbers until 2007 and then at the other end of the county, Languard in September. I have sumbitted an article for Suffolk branch of BC about this 60 years of CYs.

Jack Harrison