Potential new UK resident species

[David M]

I've spent a fair while reading butterfly-related literature since the gloom of mid-winter has been busy setting in, and one thing of interest has been the sections devoted to species that are occasionally sighted in Britain but are not indigenous.

Given that quite a few of our indigenous species seem to be rapidly extending their ranges northwards into Scotland, what are the prospects for some of the regular visiting butterfly species becoming established here in the UK?

The Queen of Spain Fritillary must surely be a prime candidate; it's common through much of northern France, regularly traverses the Channel to our south coast and its larvae feed on violets just like many of our own Fritillaries. Additionally, it is intolerant of very dry conditions (helpful if you wish to become a UK resident) and can clearly hibernate in conditions colder than those normally experienced in southern England.

Can we expect a return of the Large Tortoiseshell or maybe even more infrequent visitors such as Long-Tailed Blue?

[Matsukaze]

If dragonflies and moths are any guide, the species colonising will not be 'occasional vagrants' but species essentially unrecorded that have been spreading northwards on the other side of the Channel. The two butterflies that come to mind are the Map and Mallow Skipper, though I have my doubts about whether either could establish itself across the Channel unaided.

On a longer timescale, Scarce Swallowtail and Marbled Fritillary are also spreading north. A less likely, but possible, candidate is the Large Copper, if the Large Coppers around Paris could start to spread in the way the populations in central Europe seem to be.

[Gibster]

I'm liking this thread. I hope others will add their input. It's a real pity The Channel is such an insurmountable obstacle for so many species (not just lepidopterous) and yet, if microleps and Odonata are anything to go by, the Thames Estuary is a fantastic "jumping off/colonistation" spot. I suspect it would need more than just a gravid female (eg Scarce Swalowtail/Map etc) to start a British population, but who can tell?

Marbled Fritillary is established (illicitly) and may consolidate its toehold. Wrecclesham has shown that various species can become established in a short space of time. As for naturally occuring vagrants/future colonisers? I'd say Long-tailed Blue (natural) with the very outside chance of Geranium Bronze (becoming established).

Gibster.

[Gibster]

And - more to the point - which species may we lose in the coming decades? Is it realistically worth preserving, for example, the Mountain Ringlet? Looking forward to "new and exciting" incomers is all well and good, but what about the losers??? We can maintain and hopefully improve habitats (and their denizens), but there's not such an easy solution to climatic change.

Gibster.

[David M]

Is it realistically worth preserving, for example, the Mountain Ringlet?

Yes. Although I suspect this butterfly is more resilient than most - after all, it survives in conditions practically no other British species could tolerate.

I read your comments regarding Marbled Fritillaries, and though I accept that illicit means are being employed to introduce species to the UK, I'm mainly concerned with those that might make these isles their permanent home naturally (and, if that's the case, then Lesser Marbled Fritillary ought to arrive first given that its distribution in France is distinctly more northerly than its near relative).

[Wurzel]

I'm thinking like you Gibster. New species in the UK would be nice but maintaining the species we have would be better. What with all the talk recently about splitting and clumping maintaining extant "British" populations is surely a necessity to ensure as much variability or as large a gene pool as possible. I don't think that the "Packham Panda" scenario is on the horizon just yet but it is still a worry that the species we are enjoying now might not be around for so long...

Sorry to be on a downer - better get off the Gin and get back on the Rum!

Have a goodun

Wurzel

[Gibster]

I'll admit right now that my knowledge of butterflies falls far short of my knowledge of birds. There are MANY European species (of birds) that, on paper at least, are ready to colonise the British Isles any day now. In years gone by some, such as Serin, Fan-tailed Warbler, Bee-eater, Penduline Tit etc have been mooted as being "on the verge of colonistaion". Others such as Crested Lark, Short-toed Treecreeper and Middle-spotted Woodpecker can, from the top of a tree, look across The Channel and actually SEE Britain. Yet still they do not come. Why don't Kentish Plovers breed here? Or Night Herons and Great White Egrets? Great Reed Warblers or Bluethroats? For crying out, they all migrate after all!!!

There's a huge difference in trying to guess (educated or not) which species will make landfall in Britain next. It's another thing entirely for the process to happen with enough repetition that colonistation may occur. My money's still on Long-tailed Blue though...

Gibster.

PS Wurzel - get on the Rum asap, save your western soul!!!

[David M]

I don't think you can make a direct comparison between birds and butterflies, since the former have powers of dispersive flight far in excess of the overwhelming majority of butterflies. The UK is a formidable wintering ground for many species of bird due to its relative mildness during the winter months and consequent availability of running fresh water). Butterflies are inactive during winter in all of their life stages and therefore can be classified as wholly dormant between early November and late February at least.

I suppose the main crux of my philosophy is that if current UK species are moving northwards rapidly (which many are doing) then it ought to stand to reason that they're doing the same thing 200-500 miles further south (except for traversing the body of water that is the English Channel, of course - this is a natural obstacle to most species of butterfly).

[Pete Eeles]

New species in the UK would be nice but maintaining the species we have would be better.

Now THAT is my favourite comment of the day I couldn't agree more.

With regard to likely immigrants in the short term, Marbled Fritillary isn't on any list I've seen. Even though they seemed to have survived at Finemere Wood for a couple of years.

Andy Barker gave a great presentation at the Hampshire and Isle of Wight AGM / Members' Day in October - having analysed the information in the "Climatic Risk Atlas of European Butterflies" in some detail. Scarce Swallowtail and Long-tailed Blue are "right up there" in terms of potential residents. The biggest "loss" (in the south) was surprising to say the least. Can you guess what species it was?

Cheers,

- Pete

[David M]

The biggest "loss" (in the south) was surprising to say the least. Can you guess what species it was?

Was it Small Heath? - Jim Asher stressed how numbers were falling during the recent AGM.

[Pete Eeles]

That is, indeed, very sad. But that's not the long-term species outlook based on climate change that Andy mentioned.

Cheers,

- Pete

[Padfield]

I'm very surprised long-tailed blue was high up the list as a potential resident. I understood this to be a continuously brooded species with no real diapause stage - hence restricted in its residence to the Mediterranean area. It's certainly not resident in Switzerland. On the other hand, short-tailed blue is making a come-back in Europe. Interesting!

Guy

[Pete Eeles]

Indeed. We'd have to agree on a definition of "high" first Short-tailed Blue is also high on the list - although I don't have Andy's slides to hand, and am working from memory!

Reading the risk atlas, there are many different models applied, but scenarios depicted are quite telling in themselves:

1. Sustainable. "Focused on the achievement of a socially, environmentally and economically sustainable development".
2. Business as usual. "A continuation into the future of currently known and foreseeable socio-economic and policy trajectories".
3. Growth-applied. "A future world based on economic imperatives like primacy of the market, free trade, and globalisation".

Which is the more likely?

Cheers,

- Pete

[Padfield]

Tragically, scenario 3 is almost inevitable. Obviously, such a scenario, continued indefinitely, will be its own nemesis and lead to catastrophe as surely as night follows day. But because everyone seems to think this is in the unforeseeable future, neither the elected nor the electorate appears to appreciate there is any urgency.

Guy

[Pete Eeles]

Unfortunately, I have to agree. It's not until there is an impact on human beings that any notice will be taken.

Cheers,

- Pete

[essexbuzzard]

Scarce Swallowtail yes,but Long-tailed Blue? Although this species could arrive with increasing frequency,and occasionally breed, it could surely not survive our long,damp winters in the forseable future. So the shance of it becoming a permanant resident is probably nil.
Is the species Andy mentioned the Adonis Blue? These could be in trouble if there are more droughts-numbers crashed after the 1975-6 drought. Although there is no sign of this at the moment!

[Padfield]

The Queen of Spain Fritillary ... can clearly hibernate in conditions colder than those normally experienced in southern England.

To return to specifics, rather than doom and gloom...! Ironically, heat-loving, continuously-brooded butterflies benefit from cold winters because this helps to maintain a deep torpor. Thus, the Queen of Spain survives in Scandinavia (I think as a resident, not just a migrant, though I am happy to be corrected), despite the length of the northern winter. Britain has a maritime climate, buffered by the Gulf Stream, and has long, mild winters. I am sure this is the reason Queens never survive more than a season or two. If the climate does warm up, I can't see this resulting in Queen of Spain becoming resident unless that is accompanied by significantly colder winters (a possibility, if Arctic meltwater affects the Gulf Stream).

Guy

[Pete Eeles]

Back to doom and gloom - sorry!

Rather than a prolonged series of posts, the species that Andy suggested could be lost from the south of England (based on climate change) was the Orange-tip. Which was quite unthinkable for us all. But if the models bear up, we're in for dramatic changes in the coming years.

Cheers,

- Pete

[Gibster]

Regards species which may colonise Britain in the near future, surely what we need to be looking at are the migrant species? It is all good and well saying "southern England will be as warm as France in 20 years time" but that means diddly squat for the French butterflies that fail to migrate. The Channel is in the way!!!!! So maybe we could see a concerted influx of Clouded Yellows, maybe Pale Clouded Yellow too? Milder winters will preclude species like Camberwell Beauty successfully colonising. Large Tortoiseshells are a seemingly inexplicable mystery! Are there ANY Continental fritillaries which are long distance migrants? Red Admirals, Large Whites and Painted Ladies aside, what else migrates 100s of miles at a time? Anything???

Pete - I don't think I'd like to live in a land where Orange-tips are forced into retreat by climate change Will they head northwards then?

Gibster.

[Pete Eeles]

Andy has offered to write up his presentation, but not before the new year. Of course, any write up would be based on the risk atlas. Therefore, any comments would simply be derived from that which, I believe, does consider the mobility of species across mountain ranges and expanses of water.

Edit: Yes, Orange-tip would head north. But having spent the week frozen near Newcastle, I won't be heading north myself any time soon (apart from a visit)!

Cheers,

- Pete