January 2013

[Cotswold Cockney]

that excess of power going nowhere without an end product.

...but the end product is the heat output, which enables it to fly and reach nectar sources ahead of its competitors!

Mike

As soon as I typed that I wondered if anyone would pick up on that... well done

Meantime ... back to winter cardui sightings :~

Be interesting to know if any Lepidopterists based in Northern France have observed northwards migrations across the English Channel at any time in the depths of an English winter.

Pending that information, I believe the fact that so many are reported in the most southerly parts of the Country, even down to observations on the beach or nearby cliffs, are "red herrings". Those same areas in the far south will have numerous pockets of very favourable micro climates which could feasibly allow some butterflies to survive. Not just as adults but even complete their development from any of the earlier stages in those same favourable micro-climates. Even if the odd insect is seen coming in from the sea in January, that is no guarantee that it took off from France. It could have aborted an attempt to fly south across the Channel returning to await a better opportunity to do so when more favourable flying conditions arrive. That opportunity would be very unlikely to materialise given the time of year.

So based on the scanty and in conclusive evidence available to me so far, I shall be of the opinion that those insects seen so far south in the depths of an English Winter are home bred individuals and opportunist hibernators or semi hibernators when local conditions allow.

With extensive experience of many species of butterflies and moths in captivity, my observations show they are remarkably strong and resilient and capable of surviving surprisingly unfavourable conditions. Even very low temperatures and going on to breed when better conditions become available.

[Jack Harrison]

nomad

I am still finding it very hard to believe that this species would migrate northwards into a cold European winter from a very warm region

Overcrowding might be the explanation.

Draw a parallel with birds, Red Kites. For many years, they remained around the release areas (eg, Chilterns. Rockingham Forest) and numbers built and built; Red Kites form loose colonies. By 2005? - or whenever, the core colonies reached saturation and the birds then spread out.

Now, almost exactly a year ago, I travelled from West Norfolk to Wiltshire. There were no Kites to be seen until the Peterborough area but from then on, I was seeing them regularly. By Oxford, they were numerous with many over the Marlborough Downs. My return to Norfolk was via Bourton on the Water in the Cotswolds: they were everywhere in that area. Little Rissington disused airfield had several. I don't think they were introduced to all these places but population pressure once a certain density was reached, forced the expansion.

It could be just the same with Painted Ladies.

Jack

[Jack Harrison]

CC

So based on the scanty and in conclusive evidence available to me so far, I shall be of the opinion that those insects seen so far south in the depths of an English Winter are home bred individuals and opportunist hibernators or semi hibernators when local conditions allow.

That was what I had surmised several days ago but it did not seem to be the accepted idea.

Jack

[nomad]

Sorry, I do not see a comparison of the expansion of the Red Kite and the recent Painted Lady sightings. As the butterfly comes from the same family of our known hibernators Peacock, Small Tortoiseshell and in some years Red Admiral i believe these are semi hibernators taking advantage of the mild weather which is very soon to change. The idea may have been dismissed by some but I agree with the Cotswold cockney and think he is right.

nomad.

[MikeOxon]

I'd agree that there is a strong expansion pressure in the Spring, when numbers build up in North Africa. The migratory urge at that time of year can send Painted Ladies as far as Iceland! But the evidence seems to show that this migratory urge then falls off later in the year and that there is some Southerly migration in the Autumn. I tend to agree with Guy Padfield that the observation of these butterflies in a short warm spell indicates they are poor hibernators and are likely to succumb when the real cold weather arrives in February. They could well be late-emergers that didn't make it back across the Channel.

Mike

[Padfield]

I am finding this all very interesting. Most books repeat without comment the received wisdom that painted ladies are only resident in North Africa and do not survive the winter further north. Jeremy Thomas, as already mentioned, states that there are regular sightings of presumed immigrants on the south coast of England in January and February, which I think surprised most of us. Tristan Lafranchis adds (which I hadn't noticed before) that the species passes the winter as a chrysalis (Les papillons de jour de France, Belgique et Luxembourg et leurs chenilles, 2000). He also says, not entirely consistently, that in favourable winters it survives in Provence as an adult - also noting that it winters as a chrysalis in Gard. My Swiss book (Les papillons de jour et leurs biotopes, Ligue Suisse pour la protection de la nature, 1987) says they may survive north of the Alps as adults in mild winters. I can add to this that other species with a similar life cycle - clouded yellows and Queens of Spain - were still flying in Switzerland at the beginning of December 2012. The winter this year has been on and off at my latitude (about 46 degrees north), with early snow and cold spells punctuating very warm periods, and this pattern continues still (I saw a small tortoiseshell near my home a few days ago but we are now under thick snow again). Perhaps these are the sort of conditions that allow essentially continuously brooded species to keep going (though January sorties into the Valley have uncovered no Queens or clouded yellows so far this year).

If Lafranchis is right that the species has a natural tendency to winter as a chrysalis, and if the species was still flying and breeding into December, like the Queens and clouded yellows, then it seems quite possible that in parts of Europe adults were emerging from the chrysalis in mild periods after the solstice. It is not so surprising that such individuals would instinctively fly north.

As Mike says, my first instinct was that the painted ladies reported this year were late surviving adults (and I'm happy to believe that if it becomes the consensus) but I am keeping an open mind and I now see it as a distinct possibility they are early emergers from European pupae.

What a lot of mystery still surrounds the world's most widespread butterfly!

Guy

[David M]

If Lafranchis is right that the species has a natural tendency to winter as a chrysalis, and if the species was still flying and breeding into December, like the Queens and clouded yellows, then it seems quite possible that in parts of Europe adults were emerging from the chrysalis in mild periods after the solstice. It is not so surprising that such individuals would instinctively fly north.

That is the most convincing theory I've read thus far. I'm still finding it hard to reconcile the notion that a non-cold tolerant butterfly would voluntarily fly north across the English Channel in the depths of winter though; maybe these insects pupated in the UK?

Why would they 'instinctively' fly north at this time of year when previous evidence suggests the instinct is to fly south? After all, to use another bird analogy, cuckoos only fly south at the latter end of summer. There's no instinct driving them north at this time. It's literally the polar opposite to what their instinct tells them.

[Padfield]

Why would they 'instinctively' fly north at this time of year when previous evidence suggests the instinct is to fly south?

My suggestion (which I fully expect to be shot down ) is that a butterfly emerging from a 'wintering' chrysalis would exhibit spring behaviour. Whether the increasing daylength would be detectable by early January is doubtful, as it is less than a minute a day I believe at that time of year; but the daily decrease in daylength which might be a trigger to southward migration in autumn would certainly be lacking!

Guy

[Matsukaze]

Loads of Painted Ladies in the Malaga area last week; they showed little sign of migration and plenty of signs of territoriality, though.

[Matsukaze]

I'm still finding it hard to reconcile the notion that a non-cold tolerant butterfly would voluntarily fly north across the English Channel in the depths of winter though; maybe these insects pupated in the UK?

The south coast of England is warmer than inland France (and even inland Spain) at this time of year - not that a butterfly would be expected to know that of course...

[Padfield]

Loads of Painted Ladies in the Malaga area last week; they showed little sign of migration and plenty of signs of territoriality, though.

Presumably there was larval host plant present - so territoriality was appropriate. If a butterfly emerged at a more northerly latitude where there was no foodplant growing, perhaps that would trigger the initial migratory instinct. Then, the question would be, 'which way?' Given it had emerged in a warm period after a cold period a northward, spring-type movement seems not unreasonable (though obviously a bad idea in practice, which perhaps counts against me!).

Guy

[David M]

Why would they 'instinctively' fly north at this time of year when previous evidence suggests the instinct is to fly south?

My suggestion (which I fully expect to be shot down ) is that a butterfly emerging from a 'wintering' chrysalis would exhibit spring behaviour. Whether the increasing daylength would be detectable by early January is doubtful, as it is less than a minute a day I believe at that time of year; but the daily decrease in daylength which might be a trigger to southward migration in autumn would certainly be lacking!

Guy

Another interesting point, Guy, but as you say, the increase in daylight is minuscule between 21 December and, say, 5 January (barely 15 minutes at this latitude).

[Cotswold Cockney]

Why would they 'instinctively' fly north at this time of year when previous evidence suggests the instinct is to fly south?

My suggestion (which I fully expect to be shot down ) is that a butterfly emerging from a 'wintering' chrysalis would exhibit spring behaviour. Whether the increasing daylength would be detectable by early January is doubtful, as it is less than a minute a day I believe at that time of year; but the daily decrease in daylength which might be a trigger to southward migration in autumn would certainly be lacking!

Guy

Another interesting point, Guy, but as you say, the increase in daylight is minuscule between 21 December and, say, 5 January (barely 15 minutes at this latitude).

Cloud cover or lack of it can "increase or decrease" the impression of daylight hours by up to an hour either way at this time of year. I have been working outside the past few afternoons up until dark and noticed how much more usable natural light was still available with a cloudless sky. Right up until and for a few minutes after sunset. With a thick low cloud cover hiding the tops of the hills I had to pack up almost an hour earlier due to poor light. I noticed when the sun dropped down behind the Hill on a clear sky early evening with a beautiful sunset the warmth suddenly was no longer there and temperature would drop very rapidly. Would an insect be able to 'adjust and allow for those daylight variations and temperatures on any given day?

[Matsukaze]

Do the butterflies take the time, on emergence, to sit around and determine whether one day is longer than the previous? Is there some way they can determine this in their pupal state?

[Cotswold Cockney]

Still not seen an active butterfly this month but obviously some are active in my area. Checking "The Gloster Birder" on-line as I usually do most days produced this for yesterday :

.
Forest of Dean:~ A Peacock butterfly in the car park at Dilke Hospital at midday. (Frank Williams).
.

A couple of years ago I visited an elderly relative in that Hospital. Saw a number of deer wander out from the nearby dense forest near the Hospital grounds. There are Wild Boar there now as well as a fairly good cross section of woodland butterflies. Never knowingly seen a Purple Emperor in the deep forest despite huge areas of suitable habitat. Possibly the local mid-winter micro-climate is not ideal for the hibernating larvae. Not cold enough maybe. All other times conditions appear ideal.

[NickB]

Spotted my first on 8th - an ST had been disturbed, by the warm weather or people out walking, and went back under the foot-bridge I had just crossed, presumably to tuck-up again.
Looking at the PL debate and the picture, my first impression is that it hatched in a drier and warmer climate than I-o-W in January! I say that because the first I saw of the 2009 PL invasion were all very orange and pale chocolate-brown in colour - a colouration that would suite their native sandy, sub-Saharan or Mediterranean habitat well. Later broods in both Europe and UK appear to me to have been more salmon-pink and darker brown in colouration compared to those early immigrants. Has any one else noticed a colour-change as they go north - it is based on a limited sample....
I also feel that the warm southerly winds may have blown this beauty and deposited it on the S. Coast. I wonder if it will survive?

[dave brown]

Not sure if it adds any weight to the northward migration theory but several Southern headlands were recording migrant moths at the same time as the sightings of Painted Ladies. Portland in particular had a few nights of Silver Y's and other migrant moths.

[Neil Hulme]

Before the snow arrived here in Sussex (!), a few more records of migrant Painted Ladies have been reported to the Sussex Branch webite:

Friday 11 January 2013
Yesterday afternoon we were amazed to see a Painted Lady butterfly flying north past Shoreham Old Fort while out birding. Our first butterfly of 2013 (Peter Gibbs)
News for Saturday 5 January 2013: An interesting observation from Graeme Lyons at Woods Mill "... a surprise was a Painted Lady behaving like it was on migration; VERY fast and VERY straight." http://www.analternativenaturalhistoryo ... spot.co.uk
News for Friday 4 January 2013: A surprising first migrant of the year with a Painted Lady on the north of the reserve. (per Ivan Lang, RSPB Pagham Harbour)
News for Wednesday 26 December 2012: A Painted Lady was found settled on laundry drying on a washing line in a garden in Goring-by-Sea. Moved to a garden shed to hopefully survive the winter. (Paul Richardson)

With the exception of Graeme Lyons' observation, which is 5.5 miles inland up the Adur Valley, all sightings are from between 50 metres (Shoreham Old Fort) and a couple of hundred metres from the water's edge. Interestingly, that's more Painted Lady sightings (reported to the website) during the last two weeks in Sussex (first at the base of Beachy Head cliffs on 1st Jan), than in the entire three month period at the end of 2012! A little digging came up with another intriguing record of a Painted Lady, this time on RSPB Ramsay Island on 9th January (Lisa Morgan) - the only butterfly seen on the island so far this year.

Neil

[Cotswold Cockney]

It is quite possible for both scenarios to be the actual case here. Both successful partial home bred hibernators/emergers and occasional genuine fresh immigrants. The far south of these Islands has an extensive micro climate along much of the coast which can be very different from that only a mile or more inland.

[Neil Hulme]

Hi CC,

It's certainly true that there are localised 'warm spots' along the South Coast, but there remains a problem with the idea of recent UK emergers. Although the adult insect is actually quite robust, the Achilles' Heel in the life-cycle is the larva, which is at its most vulnerable during its latest/pupating stage. Painted Lady larvae cannot survive temperatures lower than c. 5 deg., so we need to look back at the weather during the period when this stage would have been reached, in order to explain these sightings. Even accepting that one or two robust individuals might just survive slightly lower temperatures, and accepting the existence of localised warmer microclimates, the temperature record over the whole of the UK for early December (the graph below looks the same for the latest November period) indicates that the survival of maturing larvae would not have been possible.

Neil