rarest UK butterfly

[John W]

Ok I have a question to help while away those winter hours...

What do people think is the rarest British butterfly, i.e. the one with the fewest adult butterflies per emergence?

Also, this may have the same answer, which species occupies the smallest total area of habitat?

And a third question, which species is most in danger of extinction?

Cheers
John

[millerd]

A guess: High Brown Fritillary as the answer to all three.

Dave

[Rogerdodge]

I would guess-
1/ Black Hairstreak
2/ Glanville Fritillary or perhaps Swallowtail
3/ High Brown Fritillary

[Gibster]

Also, this may have the same answer, which species occupies the smallest total area of habitat?

Surely Heath Frit and Large Blue are contenders? Oh hang on though...Marbled Frits have existed in a certain wood for some years I believe. So perhaps that's the correct answer. Or Large Tortoiseshell on the Isle of Wight should take it as a 'genuine' British species. Assuming it is!

Gibster.

[essexbuzzard]

I think perhaps Green Hairstreak is possible for the low numbers question-a widespread species it's true,but they are rarely seen in numbers,and none at all at some sites in poor years,at least in East Anglia where i live,and this is my experiance in Cornwall as well.
For the other questions,i would go along with Roger:
Swallowtail,
Defiately High Brown Frit.

[David M]

I would say Large Blue (unless we're classing them as introductions).

Of the rest, there can't be too many Swallowtails knocking about, whilst Glanville Fritillaries surely can't number more than a few hundred adults over the few sites where they're found.

[lee3764]

Duke of Burgundy!!! on all 3 counts!!
There are more Large Blues & Glanvilles & probably more High Brown Fritillaries (certainly bigger habitats) than Dukes in my opinion!! We need to preserve & increase the Dukes before it is too late!!
Cheers,
Lee (Cornwall).

[Ian Pratt]

Duke of Edinburgh on all counts especially windy headlands!!

[John W]

I remember Neil (Sussex Kipper) saying that all the Duke habitats in the country would fit into one square kilometre so you may be right!

Interesting that no-one has mentioned either the Lulworth Skipper or Chequered Skipper.

[Neil Hulme]

Hi John,
Not so long ago all the Duke habitat in the county would have fitted into one square kilometre, but fortunately the situation is not quite that bad nationally. The good news is that targeted conservation work in several areas is now meeting with success and a major BC project connecting hotspots in Hampshire and West Sussex is now on the launch-pad. This species currently seems to be reacting very well to management (we now know what it really, really wants ), so the tricky High Brown Fritillary must remain the highest level of concern.
Neil

[MikeOxon]

I think that these questions are surprisingly difficult! There's a big difference between species with very restricted habitat in Britain and those with genuinely small numbers. Stand in Blean Woods surrounded by a monoculture of Heath Fritillaries and it is hard to think of them as 'rare'! Similarly, Lulworth Skippers can be flyng in their hundreds of thousands across the Dorset military ranges but, travel a mile or two inland, and there are none. Chequered Skippers probably cover a vast tract of the Highlands and can be pretty abundant in some places, such as Ariundle, so I doubt it is in the running.

I'm not sure how High Browns are faring in the West Country but they do seem to be in steep decline, so I guess they qualify, as do Duke of Burgundy for similar reasons. I also suspect that the Swallowtail is pretty limited in numbers even in its very restricted fenland range. Large Blue is an introduction and, even on its selected sites, numbers are limited so, if it is admitted to the list, it must be a strong candidate for 'rarity'.

If we admit local races then some of the forms found in places like the Great Orme and the Hebrides may also qualify. These forms are probably the only ones truly vulnerable to 'extinction', as I think even the rarer British species are still reasonably widespread elsewhere. We should distinguish between 'extinction' and the local loss of a species, which I believe is known as 'extirpation'.

Mike