Chequeed Skipper Question for Debate

[Danny]

One of the butterlies I doubt I'll ever see is the Chequered Skipper unless I'm retired or unemployed and then I won't have the money to venture up into Scotland to catch a glimpse of the beast.

But why?

I see they're all over the place in mainland europe - Belgium France Switzerland..and here? ...Scotland!

Now I always thought Scotland was..well..cold and wet..and a bit butterfly unfriendly. Is the Chequered Skipper just being bloody minded and a tad difficult? Why doesn't it think "Let's go South a bit where it's a bit warmer and sunnier"?

Does it have really specialised conditions, like a rare food plant? The large Blue..I can understand that being rare, with the particular ants..and then there being enough of them..and the South facing slopes and the Wild Thyme blah blah blah..but the CS doesn't require ants does it.

Does it have to have really cold spells in Winter in order for it to do it's thing. Somebody told me the Camberwell Beauty needs this and that our Winters aren't cold enough in the UK. Example go to Poland and you'll see CB all over the place (I went in 1995 and it was). Poland is bloody freezing in Winter (and you have to pay a toilet lady every time you want to go for a wee).

Does it need altitude? Never really understood the altitude thing either...I'm sure Padfield could explain this one.

...whilst were at it (and I know I've asked before - but ages ago now) how come the Heath Fritillary occurs in only two places in the UK? Devon and Kent. I went to East Blean in Kent and when it's out and about there are tons of them around..how come the Heath Fritillary doesn't..well..spread it wings a bit?

With global warming there's all this talk of butterflies heading northward from the South and colonising like billyo. How come the Chequered Skipper doesn't take a taste of the South and fly down to East Sussex .

Danny

[Pete Eeles]

Is the Chequered Skipper just being bloody minded and a tad difficult? Why doesn't it think "Let's go South a bit where it's a bit warmer and sunnier"? Does it have really specialised conditions, like a rare food plant?

I believe that it does have quite specialised habitat requirements - and used to occur in England in several colonies - all of which have died out. The species certainly likes damp conditions on sheltered sites, and Purple Moor-grass (the larval foodplant). I'm not sure if the precise habitat requirements are fully-understood, otherwise the attempted reintroductions that have taken place to date would have been successful.

Somebody told me the Camberwell Beauty needs this and that our Winters aren't cold enough in the UK. Example go to Poland and you'll see CB all over the place (I went in 1995 and it was).

The CB does need cold winters, otherwise it doesn't go into a torpid state and uses up valuable fat reserves unnecessarily.

Does it need altitude?

No - most of the Scottish colonies are at sea level, I believe.

How come the Heath Fritillary occurs in only two places in the UK? Devon and Kent. I went to East Blean in Kent and when it's out and about there are tons of them around..how come the Heath Fritillary doesn't..well..spread it wings a bit?

Because it's not as mobile as some other species and there aren't sufficient "corridors" of suitable habitat (such as new clearings in woods) for it to move into.

With global warming there's all this talk of butterflies heading northward from the South and colonising like billyo. How come the Chequered Skipper doesn't take a taste of the South and fly down to East Sussex .

Same reason I suspect - not enough appropriate habitat on the way.

Cheers,

- Pete

[Mikhail]

By the way, in its English colonies the larval foodplant was False Brome Brachypodium sylvaticum.

Misha

[Pete Eeles]

Good point - thanks Misha.

Cheers,

- Pete

[Padfield]

Does it need altitude? Never really understood the altitude thing either...I'm sure Padfield could explain this one.

Chequered skipper is one of the many butterflies that in Switzerland is commoner in the mountains mainly because so much of the lower-lying land has been spoilt. I don't think it has any specific altitudinal requirement.

The species appears to be in regression in parts of Europe, including France. I don't really understand the foodplant situation as it seems to specialise to a different grass in each country - Dactylis glomerulata in Germany (a widespread and common grass in England), Calamagrostis villosa in Switzerland, Poa trivialis in Austria... But chequered skippers do have complex and special requirements (for the larvae, for the adults and with respect to hibernation conditions) and are very sensitive to environmental changes.

There's a lot of information about those requirements in the BC Action plan, here:

http://www.butterfly-conservation.org/u ... n_plan.pdf

Guy

[Roger Gibbons]

Chequered Skipper occurs quite widely in eastern and central France. I have just checked my records for the past seven years and I have seen it in ten or more separate locations in central France as well as in the Pyrenees and the French and Swiss Alps at around 1500m. Most of the central France locations were at low altitude, although in these low-lying areas it has usually been close to water. It is not a great flyer and can easily be missed; I found one near Bourg-en-Bresse in central France and soon discovered that there were a dozen or so in the same spot.

Regarding Camberwell Beauties, they also overwinter in the oak forests near the south coast of France. I usually see one or two every year in April and early May, although this year I saw six or eight in different locations. They usually occur as singles, but I have seen two together on two occasions. There is one location where I can be reasonably sure of seeing it in late April. However, I have never seen the summer brood in these regions, only at altitude in the more mountainous regions of the French Alps, the Cevennes, and the Pyrenees. I do not doubt what others may say, but my experience is that they head south into the warm Mediterranean olive belt to overwinter.

With regard to the conditions needed to thrive, for Heath Fritillary in particular, the habitat requirements in France are often very different to those in the UK. Heath Fritillary is one of the commonest butterflies in France and seems not to be restricted to any particular type of habitat, and that is also true of Glanville Fritillary. Marsh Fritillary is often common and I find it in great numbers in the spring in very dry locations. All of these fritillaries are found quite commonly at high altitude of 2000m and above. Swallowtail is another example of a species that has very narrow habitat requirements in the UK but is widespread (although not as common as Scarce Swallowtail) across a wide range of terrains in France, including at higher altitudes of 1000-1500m.

There is so much we don't know as yet.

Roger

[Padfield]

I do not doubt what others may say, but my experience is that [Camberwell beauties] head south into the warm Mediterranean olive belt to overwinter.

Summer Camberwell beauties are most commonly seen away from their breeding sites, in dispersal phase. They hibernate at the breeding site and I understand those that don't disperse go into hibernation very quickly. One interpretation of your observations is that there is a resident population in that warm Mediterranean olive belt and you don't see them there in the summer because they're on the wing for such a short time. In the spring, however, they engage in breeding activity for a month or two (I was still seeing them at the breeding sites in June this year) and are easy to find.

I frequently see my summer CBs high up mountains. This year I saw one cruising through up at Bretaye, near Villars, at about 1800m. They don't breed anywhere near there, to the best of my knowledge.

Finally, on the same subject, it's interesting that after the hardest winter in recent times we all reported a bumper crop of CBs this spring. You can't draw conclusions from just one year, but it certainly doesn't contradict the idea that they thrive best when the winters are harsh.

Guy

[Roger Gibbons]

One interpretation of your observations is that there is a resident population in that warm Mediterranean olive belt and you don't see them there in the summer because they're on the wing for such a short time.

Maybe, but for the last four years I have spent most of April-October butterfly watching throughout Var and the Alpes-Maritimes (although not so much in July and August for the past two years) and have not seen summer brood Camberwell Beauties. Also, from about the third week in June in southern-to-mid Var, the entire terrain becomes baked and very little flies, only the heat-loving species and very few of them. I haven’t seen any in the higher altitudes (around 1000m) of northern Var and the Alpes-de-Haute-Provence further north, only in the Hautes-Alpes and Isere.

I don’t draw any hard and fast conclusions or postulate any theories on the basis of my observations, I just report what I have seen. Maybe with more data and corroborative (or not) observations we can understand more about their movements.

Roger

[Danny]

So if chequered skipper larvae is happy to eat bog standard grass in Germany, how come it doesn't start gnoshing up UK bog standard grass and get it's corridors going down to East Sussex (it's a lot warmer and dryer than Cold and Wet Scotland!)..

I wonder if certain populations of Chequered Skippers have evolved to prefer different food plants...in which case is this an example of natural selection/evolution actually taking place? (Woffling now)..

..and if Camberwell Beauties dig the South of France as much as Poland..then how come we don't get it here very much?

..so Heath Frits are mega common in France! Wow! I mean is the South of England *that* much different from Brittany/Normandy?..What makes East Blean Woods the same as ..*all* of France??!!

Danny

[Padfield]

Lots of questions! I suspect that if someone here actually knew the answers it would take more than a brief post to communicate them! Ecosystems are wonderfully complex things, and what Britain lacks in numbers of species it amply makes up for in the sheer interest of its remaining wild communities.

Having said that, I would guess Britain's position as a northerly Atlantic island (or rather, group of islands!) must have a big bearing on things, both from the point of view of the geographical isolation of its butterfly populations and the climate. France is a huge landmass that is hotter in summer and colder in winter (mostly) than Britain. Switzerland is entirely landlocked and the swings here are really extreme - the Rhône Valley has a Mediterranean climate in summer but may be under snow and frost for weeks on end (months, this year!) in the winter. Britain's climate is buffered by the sea all around.

Guy

[alex mclennan]

On a lighter note, all the chequered skippers I've seen have been on the European mainland. I've never taken the trouble to go to Scotland to see them. So Adrian Riley won't allow my claim to have seen all the British butterflies until I go to Scotland and find a real Chequered McSkipper as he calls them!
Alex

[Matsukaze]

If you can track down a copy of "The Ecology and Conservation of British Butterflies" (edited by Pullin, 1995) there is an article by N. Ravenscroft on the Chequered Skipper which is well worth a read. In Scotland, it exists in large tracts of suitable habitat across which it is quite mobile. The English colonies did not have large expanses of habitat, and may have lost the ability to disperse.

Why its English populations were so geographically restricted I am not sure. I would have thought damp, wooded areas of Kent, Sussex and Surrey would have been suitable for the species in the 1800s at least.

The Heath Fritillary used to occur in scattered pockets across southern England as far north as Staffordshire. Possibly it was always local as its main foodplant here needs acid soils. I am guessing here but the areas in south-east and south-west England it survives in are those that were affected least by nineteenth-century agricultural change (enclosure). I get the impression the Exmoor populations are more mobile and able to colonise suitable habitat than the Kent/Essex populations - can anyone comment on this?

If the Camberwell Beauty is restricted by winter temperature then surely it should have been resident in parts of Britain during the Little Ice Age, and been recorded as such by the early butterfly collectors?

[Danny]

What's the Little Ice age?

I thought it was what happens after the age of 45.

Danny

[Piers]

Heath Fritillary in England will lay on a variety of plants (cow wheat, germander speedwell, ribwort plantain, foxglove etc.) and the larvae will consume a few more still, so they are not strictly confined to acidic soils.

In England the adult Heath Fritillary is an exceptionally sedentary butterfly, which is a major factor in it's currently limited distribution, and it's habitat requirements in this country are extraordinarily exacting, relying upon a precise microclimate for successful larval development. True, this microclimate may currently exist in many areas of the country where the butterfly does not, however this immobile species does not have the mechanism for colonising areas that are separated by even small tracts of unfavourable habitat. It may also be the case that even in areas with good Heath Fritillary potential, the optimum microclimate may be transient and exist for just a few years within a larger landscape, and unless there were suitable corridors between the areas of optimum habitat the populations would disappear after a few years. This explains why the colonies on Exmoor have fared reasonably well; within this landscape there exist the means for the adult butterflies dispersal within a 'meta population'.

When the Heath Fritillary colonised this country following the last ice age (about 10,000 years ago) there followed a period of about 6,000 years where the climate in Britain was closer to that of central France, and it was during this period that the butterfly probably would have fared best in Britain, having a climate more conducive to less exacting habitat requirements. It would not have been common, but certainly well distributed; Britain was largely wooded but due to the favourable climate the butterflies habitat requirements would have been less precise so aiding dispersal between it's fragmented colonies.

Historically coppiced woodland provided the ideal conditions for this butterfly in Britain, and the butterfly probably spent about 5,000 years adapting to this (perfect) man made habitat, and evolving to be far less mobile as the need to travel far to find suitable habitat did not exist.

All of a sudden, within the last century, these woodland management practises ceased, and a butterfly that had spent 5,000 years or so evolving to exploit a particularly habitat found that this habitat was suddenly gone. Add to this a period of climatic cooling between the 1940's and the late 1970's and you have a combination of factors that contrived to ensure the species demise in Britain, and indeed the Heath Fritillary was in decline for the majority of the 20th century. By 1980 there were probably no more than six extant colonies in Britain. Had there not been herculean efforts made by the conservation community in the 1980's and subsequently, it is highly likely that this butterfly would have gone the way of the Large Blue.

Felix.