UNORTHODOX BUTTERFLY NOTEBOOKS NO 5: MAY 2001 – SEPTEMBER 2001

 

May 19th 2001: Otley, West Yorks

Visited the Chevin. As the sky remained overcast we stayed on the big field. We counted many Green Hairstreaks which had crawled to the top of the bilberry to catch whatever there was of the sun's rays. Once disturbed a few flew a short distance: a couple even making immediately for the young saplings on which to perch. However, none were to be found mating – sunshine was needed for that.

Having spent around six hours observing hairstreaks one begins to live on intimate terms with them. Their camouflage is not an exact reproduction of a specific feature like a leaf insect for instance. It is an abstract synthesis, a resemblance to rather than a copy, of many different things. The viridian tint of the wings for instance is almost equivalent to the bud of the bilberry before it becomes a mauve flower. I also noticed a semi-punctata at the base of a bilberry plant. I was laying on the hair moss whose buds bore a striking resemblance to the arc of dots on the Green Hairstreaks wings and which in this instance helped break up the form of the wings. Does this give the butterfly some form of protection from say spiders which have simple eyes and maybe therefore capable of greater visual resolution/ in the case of the bilberry Green Hairstreaks as the more speculative analogies one makes the closer one comes to the truth of this compound insect which transfigures rather than reflecting different aspects of its environment.

 

20th May 2001: Eldwick, Bradford, West Yorks

Visited the Prince of Wales Park. Hazy sunshine to begin with then a covering of cloud lasting all day into early evening. However a slight breeze ensured it was warm. We duly found the Green Hairstreak resting on grass, heather and bilberry. I noticed an eccentric looking woman observing us. It was Susan Stead of Bradford Urban Wildlife Group. Her infectious enthusiasm was immediately evident. She showed us the spot where most of the Green Hairstreaks were to be found and was rather surprised we had seen so many on the lower slopes of the bilberry area.

She claimed importantly that it was the area of dead bracken which was crucial to the over-wintering pupae. Certainly it was warmer than the surrounding area and in fact a couple of Green Hairstreaks were to be seen flattened against the dead stalks of bracken soaking up whatever warmth they could. She had not seen any perching but later on around 4 30 I noticed a couple flying near the top of a birch tree some twenty feet from the ground. They also appeared to be roosting here because I did not see them come down into the bilberry. The higher reaches of the birch were preferred to the lower branches because at that time of the day they also caught the sun's rays whereas the lower branches remained in shadow,

A jay was to be seen hopping about just as on the Chevin yesterday. This one would hop down from the branches and disappear into the bilberry. It was clearly attracted by the bilberry's insect population. None of the other birds were quite so blatant – at least whilst humans were in the park. I noticed a blue tit high up in a birch tree with an insect in its beak. Susan claimed that 1997 was the critical year for the Green Hairstreak, the year in which it made its presence felt meaning the combination of warm winters since 1991 have finally born fruit. The cool summers of the following years made no difference to the insects' consolidation of newly conquered territory. Further, they may even have expanded during that time

Warmth: Yesterday the insects would not have been in evidence in the Prince of Wales Park. They may have taken to 'basking' in the tree tops coming out from the undersides of the leaves. The 'big field' on the Chevin is a scree slope from which rocks have tumbled down from the above quarry at the top of the field. The heat absorbing property of the millstone grit has created a 'warming pan' effect as the hillside appears to have only a shallow covering of soil.

 

21st May 2001: Otley Chevin, West Yorks

Visit to Ghyll Brow west of the Chevin. Ignored foot and mouth warnings even ripping down a notice. Waited for the cloud to clear then moved down to the lower slopes where we quickly spotted the Green Hairstreak. We reckon it is a large site possibly numbering from 500-1000.They showed a fondness for gorse. I even saw one nectaring on the gorse flower. In fact very few indeed were to be found on the bilberry. Most preferred to perch, roost and sun themselves on the branches of hawthorn, rowan, oak and gorse. They also tended to favour the upper branches but this maybe because the sun never really came out for any length of time.

The behaviour of the butterfly varies from site to site. The Ghyll Brow population rarely seems to come down whereas the Chevin population show a fondness for basking on the bilberry. Indeed they roost there with the Ghyll Brow population appearing to prefer the trees. At the most there was just over an hour's sunshine. After that a dark cloud stayed put above Ilkley Moor and the Chevin all day with areas to either side including Bradford enjoying several hours of sunshine.

Ghyll Brow is also more bio diverse than the Chevin. I noticed two Latticed Heath (small specimens) and Common Heaths. The planted tree population was also more diverse and possibly the same may be said of the bird life. A red/purple flowering plant which was quite common could be either common vetch or smooth tar.

 

22nd May 2001: Cottingley, Shipley High Moor, Stoney Ridge Hospital, New Brighton, Stoney Lee Mid School, Bradford 16. Horton Bank Country Park, Clayton, Fall Top Farm, Hanging Falls, Fall Top Quarries, Bradford 14. Ambler Thorn, Bradford 13, Oats Royd, Royd Hill, The gulf, Strines Beck, Holmfield Industrial Estate. Visit to Ambler Thorn

Within seconds had seen a Green Hairstreak. This was a bilberry population preferring the plant to anything else. On lower slopes a female (possibly) would settle on the grass and on the lower branches of newly planted conifer and larch.

 

Shipley, Northcliffe Woods

The fringe of bilberry - often quite thick - has been grubbed out besides the golf course. Almost certainly it would have accommodated a small population of Green Hairstreak. Made my hate golfers and golf courses even more. It is the most selfish and proprietorial of sports claiming huge tracts of land on the fringes of towns from which nature is expelled.

 

Stoney Ridge

Supports a population of some 50 to 100 Green Hairstreaks. May even feed on gorse given the predilection they had for the plant. This gorse had yet to bloom but even so it lost none of its attractive power to the butterfly and twice I noticed a Green Hairstreak land on an abandoned cider bottle roughly the colour of the insect.

Returned to Clayton and Fall Top Quarries late in the day. In fact it was well after six in the evening. David disturbed one butterfly but there just has to be many more. An irate farmer came tearing across the field on a dirt track bike. He skidded to a halt and promptly fell off unlike Stevie McQueen. I placated him by saying I was from Leeds University. He thought we were poachers. Returned to Clayton along paths where there were no signs to be seen prohibiting entry because of the big foot and mouth epidemic. David helped a couple of weight lifters with a mowing machine in Clayton. It had careered into the fence because the driver had had one too many. This little touch made me dislike Clayton less.

 

23rd May 2001: Back to Brow Ghyll

Brow Ghyll and Beacon Hill Moor. On Brow Ghyll the Green Hairstreaks were not where I hoped to see them i.e. on the gorse towards the top. Mainly they were to be found lower down. However, they were perching higher up the hillsides some 50 yds towards the Chevin. It really was inexplicable. Maybe the males like to move on and patrol another district while the females restrict themselves to covering the bilberry looking for suitable egg laying sites. However, the butterflies do seem to vary their activity from day to day contributing to their elusiveness. A slight drop or rise in temperature can cause their behaviour to change dramatically. For instance, the Green Hairstreaks on Ghyll Brow suddenly disappeared for a few minutes – inexplicably. But I also noticed the Long Horn moths antennae also disappeared at this point. It was like some intro-specific signal amongst several insects which went unregistered amongst us humans. The merest change in temperature or the sun's luminosity perhaps?

On Beacon Hill (Surprise View) we found a fairly widespread Green Hairstreak colony mainly restricted to the lower and middle slopes. Some showed a preference for sheltered clearings, a warden claimed emphatically there were no Green Hairstreaks on Surprise View. Later I saw him watching us and writing notes in his book. Around 5 o clock we both noticed Green Hairstreaks on a path possibly sunning themselves. This was unusual behaviour which neither of us had witnessed before.

Meadow pipits were much in evidence on Surprise View. They seem able to land with ease on sprigs of bilberry and survey the surrounding scene without toppling over. They must harvest many, many insects amongst which will be the Green Hairstreak. It is possibly a reason why they are absent from the more open stretches of moorland. Temperature: 23c, 73 f.

The stupid synthetic cubist guitar at the top of surprise view steps. Someone please chop it down. Victory to the trees not art.

 

24th May 2001: Ambler Thorn, Bradford

It is difficult to be sure if the hairstreaks taking to the grass and resting there are females or males. I noticed a couple of butterflies leaving their perches to go down in the grass as well as on the bilberry. I think they are extremely sensitive to temperature and the intensity of the sun's rays. Without a doubt half a degree can alter their behaviour significantly.

The Holmfield Industrial Estate was a disappointment. The patches of bilberry were insufficient to support any butterfly. The railway cutting has been filled with water creating an unusual environment. However we found hairstreaks on a very exposed bankside by the side of Windy Bank Lane going from Ovenden to Queensbury. Trees were few and far between on this bleak hillside and these were rather stunted. As expected we found hairstreaks on the bank side running from Queensbury to Booth Town. However, they easily preferred the south facing slopes of Crooked Lane where they generally kept to the fringe of fir trees shooting off high into the trees where they would become lost to view. By four in the afternoon they had quietened down easier to photograph. By 4 45 they had all but settled down for the night. I got the impression the butterflies on Holly Bank were a little smaller.

 

25th May 2001: Holly Bank Bluff between Bradford and Halifax

Concentrated on Howcans Lane. In spite of a dull start the sun did come out – hot – around midday. However, we did not see one Green Hairstreak on Howcans Path. Yet the environment seemed perfect. What to think? It may not even have arrived. In which case how long will it take? One year, two years? At least there is some kind of external yardstick now which combined with a planting policy from Horton Country Park, via Bracken Hill to the Boars Well may tell us something about the speed of the Green Hairstreaks expansion in the Bradford area.

They were flying for sure on the site by Crooked Lane. However, they seemed to prefer the upper slopes to the lower slopes. But to our amazement we found them on a scrawny patch next to the Holmfield Industrial Estate. Clumps of heather had once been there but had now given up the ghost and virtually all that was left were brittle, woody stalks. Maybe this little unpromising patch says something about the advance of bilberry and the retreat of heather in the Bradford area. Thin patches of bilberry are to be found on Holly Bank by the side of Crooked Lane. As bilberry spreads by a root system it will have the effect of knitting the soil together and preventing soil creep. The conifers must have been planted with that end in view. The hoof marks of cows and bulls could clearly be seen and if it wasn't for this binding the bank side would be crumbling away constantly. To see the Green Hairstreaks in the vicinity of old factories was definitively the crowning glory of a good week in which we have found six new sites. This example of the factory proletariat of Green Hairstreaks was an ab: caecus.

Moved onto Station Road, Queensbury. The old station is a truly fascinating site. In years to come it could be a wonderful nature reserve. Many Orange Tips were to be seen flying around. All were males. Whatever has happened to the females? Much jack-by-the-hedge in evidence. The old tunnel to Halifax was magnificent. What a marvellous line in general, a monument to railway mania which unfortunately was abandoned. It was that moment when capital in an excess of greed created something memorable. Would there ever come a time when we might set our collective mind together and ponder the feasibility of re-opening it after a fashion?

The weather conditions throughout the week have been near perfect. I doubt if we will ever have this run of good luck again. We have found out more in one week than in three previous years. The Green Hairstreak is a very elusive butterfly almost one that hides from itself while it colonises vast areas unseen.

The factory proletariat of the Green Hairstreak living on bread 'n' dripping this shorn patch of bilberry.

 

28th May 2001: Mitcham Common, South London, Surrey

Green Hairstreaks are there but very few in numbers. We counted three in all in the space of one and a half hours. It was a sunny, hot day and therefore perfect for them. They did not seem to have a special spot where they congregated as on Banstead Downs or, at least, we did not find one.

Moved onto New Addington using the tram. We were there in no time but had trouble finding a path onto Hutchinson's Bank. The housing estate had been built on a close formation pattern with the back gardens overlooking the bank side. Rather than to create a sense of security as in middle class housing developments this was designed to keep the residents in as it was a council estate. The older 1930s housing development was a good 75 yards back and it must have once opened directly onto Hutchinson's Bank. There were a number of Green Hairstreaks to be seen. Several were of the ab: caecus form as was the first we saw on Mitcham Common. As there was no gorse we assumed they were feeding on birds foot trefoil. The Green Hairstreaks on Hutchinson's Bank I am convinced were a different shade of green than those in West Yorks. The mean average here reflected the existing natural environment and was therefore less bluish – or viridian.

There were many Dingy Skippers comparable in fact to the numbers we used to see in County Durham. The biggest surprise of all came when we caught sight of a Small Blue. It settled down around 4 o clock and I was able to take some photos. It showed a fondness for kidney vetch, its food plant. It would linger awhile on the unopened flowerets and may have been nectaring. A Common Blue would dive bomb the small blue if it strayed into its territory. As we left another Small Blue appeared on the scene but did not stay. When disturbed the blue would fly some eight or nine feet up into bushes but never once flew over them staying put within a particular territory returning after a while to flit about the chalk grassland.

 

11th June 2001: Banstead Downs near Sutton, South West London

We went first to down view where we had seen the Small Blue some five years ago. I particularly wanted a photograph them close to the road because they do inhabit the grass verges on occasion apparently oblivious to the passing traffic. We did see several Brown Argus but it clouded over so we were denied getting the photos we wanted with passing traffic in the background. The scrub woodland had been cleared forming a far larger clearing than when we were last there but there was no kidney vetch to be seen anywhere. Plenty of nodding thistle though and obviously a magnet for Marbled White.

Talked to a young enthusiast who knew much about local butterfly populations. It certainly was not an 'educated accent' and all the more encouraging for that. Significantly however he had not taken part in the winter clearing programme on Banstead Downs preferring to maintain a distance from official bodies.

We did find the Small Blue on Banstead Downs proper though they were few in number. They tended to concentrate in the dell which a few weeks earlier a number of Green Hairstreaks could be seen flying. There was also a male Common Blue and a couple of Brown Argus. The Small Blues would buzz the Common Blue and both species would alight on plants sometimes only one foot apart. I managed to get a photo of the two together but the Common Blue came out blurred and barely visible. A Surrey butterfly conservationist - Howard Whiting – said he thought the males attracted the females into the sheltered hollows though there was a total absence of kidney vetch. It would be interesting to establish if the Small Blue preferred to mate in this particular spot rather than in areas containing its food plant. Apparently there is also a small second generation in August restricted to this sunny warm dell. Towards late afternoon there is a significant alteration in their behaviour when the butterflies commence to alight on small shrubs often as high as five foot from the herbage. I was unable to obtain any photograph of this phenomenon.

We also saw a few Oak Eggars flying at great speed across the down weaving around the hawthorn scrub becoming rapidly lost to view. I also found some three dozen Emperor caterpillars which I initially took to be Oak Eggars feeding on bramble. Some were feeding parallel to each other on leaves of bramble. This regimented feeding contrasted markedly with the gregarious behaviour of the Small Tortoiseshell caterpillars that crawl all over each other in a frenzied fashion raising their heads at the approach of danger to give the impression of a writhing single hydro-headed creature.

 

22nd June 2001: Cowpasture Wood, Northants

We found the Black Hairstreak practically instantly on "the most photographed bramble bush in the world" according to the warden. Though the day clouded over we remained in the wood to observe the hairstreaks habit during late afternoon. It must have stopped feeding shortly before 4 pm taking then to resting on the leaves of blackthorn slowly climbing up the banks of blackthorn as the sun declined in the sky. Earlier on the butterfly had shown a liking for the oaks and ash. It would often land on leaves which had been attacked by insects or had partially withered and in this way successfully camouflaged themselves. But they overwhelmingly preferred the blackthorn. Some of the blackthorn had been attacked by a lethal fungus which helped camouflage the insect. But the lower branches were the most subject to attack and the Black Hairstreak avoided these.

At one point a Black Hairstreak landed on the back of a child's chair and stayed there some time. It was the lowest point the hairstreak settled all day. Immediately the pushchair was surrounded by voracious photographers anxious to secure a prize winning shot. They never stopped to ask why the Black Hairstreak was attracted to the pushchair. One was particularly aggressive with his 500 mm telephoto lens. This expensive equipment automatically conferred priority and it was obvious they despised our 'inferior' equipment. In fact they were taking images not photographs of real butterflies. There surroundings were of no importance to these animals. They consumed insects they did not observe them. Within half an hour they had thankfully disappeared from the scene just as we anticipated. They had spent the week going from one reservation to another flaunting their expensive junk – for at the end of the day that's what it was – and an intelligent use of a brownie box camera could have yielded better results, when I moved off to look at an adjacent bramble bush passing as I did so their half open camera bags, the most unpleasant of the photographers followed – just as I thought he would. The message was clear – not only was our equipment inferior but we were also suspicious individuals and potential robbers. Their way of viewing nature was the industrialisation of natural history.

The binoculists are as naturalists the more profound observing nature rather than consuming it. They are also nicer people letting others take a look. But these photographers took the place over like nature paparazzi.

The Black Hairstreaks particularly in late afternoon had a tendency to flatten themselves against the leaves to absorb the maximum heat possible from the sun, similar in fact to the Green Hairstreak which will do it any time of the day with greater success, the insects' inclined plane being almost that of the leaf. By 4 45 the butterflies had practically ceased flying and had commenced roosting on sprays of blackthorn. Occasionally they would take to the air but not for long alighting on an adjacent branch. To a trained eye they were not difficult to detect. More than anything else it was the shape that gave them away and not their colour.

 

24th June 2001: Strumpshaw Fen, Norfolk

(From a letter to Beryl): I have been burnt to a cinder and attacked by unknown creatures. On Sunday I visited Strumpshaw Fen near Norwich to see the Swallowtails. There wasn't a cloud in the sky all day and all the people we met were friendly and wanted to talk. It is owned by the RSPB and so the majority of people who visit the place are 'birders'. I think half the pleasure of these places is the pleasure of encounter and the drift that then begins to take place. I don't think there is one naturalist who is not now aware of how precarious huge swathes of wild life have become. So talk turns quickly to impending ecological catastrophe. And the possible extinction of the human race within one hundred years or so if there is not drastic change. It is warming not to find a voice raised in dissent or to be confronted with the blank looks of the living dead. The question then becomes what practically is to be done about it. One was I suspect longing for a cull of human beings to reduce the world's 3 billion. He was an anti-humanist and spoke in the first person plural "we" (i.e. human beings) a kind of abstract speciation I cannot agree with. Both David and I kept quiet for fear of arousing a heated controversy but we both agreed that in future we must not be so reticent.

I liked the demographic profile too – young, old and in between. Age ceases to be an obstacle to communication and in that sense is similar to the workplace. The wives unfortunately tend to retire to the sidelines but single women more readily will take their place alongside the men.

 

26th June 2001: Bradford, West Yorks

Visited Common Blue sites across Bradford. We failed to find them at West Royd in spite of the presence of their foodplant. However our search was rewarded in the disused quarries under Wrose where we found some six individuals. Only one was a female and though it never opened its wings it was beyond doubt a blue female. There were a couple of Meadow Browns and several Cinnabars. These would alight for a fraction of a second on the stalks of moor grass. Towed two and fro by the wind they were still very responsive to the movement of a large shape like that of a human. We felt that the Common Blues had just emerged and were awaiting the arrival of the females. One did nectar on the trefoil and another on hawksbit but most preferred to perch on the grass stalks and linger awhile.

We then went on to Shipley Station Meadow. We saw around 4 males but not one female Common Blue. Behind platform 1 not one butterfly was to be seen which was hugely disappointing. Rail Track had sprayed the platforms and entrances to the platforms with a strong herbicide which probably had put paid to at least half of the population. The grassed areas around the car park had been cut and sprayed. I felt sick and disgusted just liking at it.

We then caught the 624 bus to Wrose discovering a huge site overflowing with trefoil. Maybe we saw about 8 one of which was a blue female. On a good year there must be many more and the York stone quarries undoubtedly contributes the main population in the Bradford area. There were also a couple of Walls and Cinnabars as well as several large skippers. The disused Gaisby Quarries were just one of those exciting areas. Everywhere we looked there was potential for wonder. A broken down shed of corrugated iron with tree branches forming a back wall in a manner of speaking, was suggestive of a new architecture. Unlike a nature reserve it was a place one wanted to be.

We think throughout the era of steam trains and smoke stack industry the Common Blue clung onto these heights eventually expanding into the valley bottoms and extending all the way from Shipley station to Foster Square station in the centre of Bradford. Eventually the Common Blue is likely to cover all of the Yorkshire quarries once the trefoil becomes established on the newer spoil heaps which may however be several years away. Finally it will reach the fringes of Bolton woods.

 

27th June 2001: Brockadale near Pontefract, West Yorks

The Marbled White was few in number – nothing like the teeming numbers that greeted me last year. The few that had emerged tended to congregate around the pylon that bestrides Brockadale. We also saw our first Ringlet there. The field had been converted into meadow and for the first year it was a highly successful one. A farmer had seeded it = much clover, trefoil, vipers bugloss, one pyramid orchid and a bell flower, undoubtedly the marbled white will breed here. Last year I saw it in the lane leading to the car park nectaring on hedge parsley. In fact this plant maybe a major factor in its dispersal in the north. I have never seen a Marbled White feeding on the plant in the south. Thistles and nettles had been sprayed with a selective herbicide which may not have been a good idea as Marbled Whites are attracted to thistles

David feels sure we saw probably three Brown Argus. All were most certainly dished being the end of the season for the Brown Argus. Common Blues were on the wing but the majority were males and in prime condition. So why were the females so battered? The Common Blue also appeared to show no interest in the putative 'females'. If they were Brown Argus it is their first sighting in west Yorkshire.

Met the manager of Brockadale. Maybe he was a bit miffed with us for walking in his precious meadow but softened once we congratulated him. He automatically assumed we had a car but was most impressed when we told him we were anti car and opted for travel by bus. He seemed to have considerable farming knowledge.

 

28th June 2001: Wrose Quarries, Gaisby, Bradford.

Probably saw some 10 to 15 Common Blues, all male. Usually males were to be seen flying together in contiguous territory. When their paths crossed they would chase each other. High up on the Gaisby Quarry side a pair were doing just that oblivious to the gusts of wind which would sweep them up onto the quarry top where they would be lost to view. On occasion the wind must lift a butterfly high into the air where it would be swept far away from its breeding ground. If that butterfly was a female anxious to escape the unwanted attention of the male then it will help disperse the butterfly.

On the very top of the quarry a pair of male Common Blues were flying. I thought it unlikely any Common Blues would be there. It does indicate the Common Blue is fairly evenly widespread over the site wherever trefoil is to be found. They also like to rest on mill stone grit stones scattered all over the banksides. I have never noted behaviour of this sort before. They also seem to like flying into the wind putting up a mighty effort as they do so. Against the waving grass they are less visible than when flitting from flower to flower. However, a couple of Common Blues had beak marks on their forewings. From when I first saw aged around 11 or 12 I can remember them valiantly battling against the wind on Storrs Hill in Ossett, West Yorks. No other blue to my recollection does this.

It is to be hoped that what we saw was only the beginning of the emergence and that the males were building up their numbers prior to the emergence of the females.

 

29th June 2001: Shipley Station Meadow and Windhill, West Yorks

Still only male Common Blues flying around. One took off over the escarpment leading to the meadow below. At Shipley station females were now in evidence, though still in fewer numbers than the males. Every female we saw was, to some degree, a blue female. Not only that but there was variation within the variation. On one female there was a reduction in the orange lunules on the upper wing. These had been replaced on outer margins by the hint of a white flash. The orange markings were however noticeably unaffected on the underside upper wing. Another female displayed increased white margins on the upper side under wings; it was more visible from a distance of some six foot than close to where it lost some of its distinctiveness. The optical difference which can exaggerate variation if viewed from a distance must be of some importance. To capture this effect 600 asa to 1000 asa might be more telling than a fine grained film.

When chased by males, females can shoot up into the trees to shake them off. Against the sunlit leaves, white clouds and patches of blue they are impossible to follow. Trying to escape the unwanted attention of the males the females could easily become reluctant colonisers of new territory. Winds will assist this dispersal. Common Blues like to rest on tall grass when their wings are folded and if resting on the grass florets they are quite difficult to detect. The grass spikelets resemble the angular markings of the under wings. When swept by a strong wind the Common Blue will, with each gust, desperately alter its position as if clinging on for dear life. One moment the under wings will be clearly silhouetted on the grass stalk, the next moment, the butterfly will be edge on, a faint line in the grass seemingly doing a vanishing trick if one's attention is distracted for a brief moment, this perching behaviour on sheep's fescue or meadow grass tossed to and fro by the wind is very effective as a survival technique. No bird or spider would attack when the butterfly is clinging so precariously onto the often violently waving grass stalk.

Common Blue males have a habit of flying into the wind. If it is a high wind they barely make much headway, their wings fluttering against the streaming grasses. Then of a sudden they will streak off in the direction of the wind forming a visual curve almost parallel to that of the bending grass. This extreme contrast of movement would be very puzzling to a potential predator like a bird attracted to the blue wings. Maybe it is one reason why Common Blues are to be found on windswept terrain whilst close by there more inviting, sheltered from the wind, sites. Rubbish can also provide an effective camouflage particularly discarded plastic bottles reflecting blue light. Also when flying against steel grey fences such as one finds around marshalling yards they are actually impossible to follow. It would be interesting to investigate the relationship between the Common Blue and industry particularly the fondness for birds foot trefoil for embankments, railway sidings and quarries. No other blue in Britain was able to make this transition; did cinder paths, decaying tar macadam roads where grass was unable to shade out trefoil help spread the butterfly?

 

30th June 2001: Shipley Station Meadow, West Yorks

There is a significant degree of variation amongst the Common Blue females. Witnessed a couple mating. Whether there was any lengthy optical exchange of signals I cannot say. The male appeared to surprise the female as it flew over the grass. Mating then took place extremely rapidly. They crawled up a timothy grass stalk and looked as if they were prepared to go all the way to the floweret. The female led the way with the male walking backwards up the stem. A grass stalk suddenly traversed the timothy stalk and the female blue caught hold of it the pair of them eventually transferring to it. I detached the stalk and put the pair on some St john's wort. The pair then gyrated around a bracken frond at right angle to the stem with the male leading the way and then the female. Their coupling did not seem to be a happy affair. In fact it was more like a struggle to stay together what with the high wind continuously buffeting the pair as well. The female briefly opened its wings a little. After they had parted both butterflies turned to face each other as if to say thank you. Their legs even lightly touched. Then the male opened its wings followed by the female before the male finally took off.

A female had closed its wings amongst a patch of trefoil which had already begun to seed. It was a very effective background camouflage for the resting insect, the white claw feet of the seeding trefoil tinged with a bluish red and matching the folded hind wings. There was an absence of orange lunules on the upper costal angle and no sign of a white flash. But on the under wings the inner margin had a pronounced white appearance. (Have photos of this).

 

1st July 2001: A visit to Healey Mills Marshalling Yards, Horbury, West Yorks

Going into the marshalling yards where the path branched off from Healey Bottoms I immediately spotted a blue female. Minor but significant differences from those in Shipley Station Meadow. All four upper side wings had distinct white spots rather as does the Northern Brown Argus. In the sidings there were masses of birds foot trefoil. In fact in places the ground was literally carpeted with it some of it in bloom, some already seeding and the rest still to come out. In fact slithered down a railway embankment I saw a male Common Blue – a very dished specimen indeed which I managed to photograph. A short while later I caught sight of what I think was a blue female but since it never opened its wings it may have been a typical brown female. It was a very windy day with intermittent sunshine and the blues were instantly swept along by the wind once disturbed. However, there were undoubtedly a high proportion of blue females in varying degrees perhaps as high as two thirds. Obviously they had been out for sometime in the marshalling yards perhaps as much as a week in advance of Shipley Station Meadow. It is sheltered from the wind and a sun trap with patches of bare earth and at best a sparse covering of grass. This exceptionally poor soil was ideal for trefoil and a perfect site for the Common Blue. In all probability there is no equivalent site in West Yorkshire and it is possibly double brooded as a result of the uniquely favourable conditions.

I was able to observe a courtship ritual. The female (a blue female) appeared to be beginning to send out signals to a male that chanced upon it. By flying directly into the wind and vibrating its wings furiously it remained almost stationary some four inches above the tips of the trefoil. The male did the same perhaps a couple of inches behind the female. It was joined by another male some twenty seconds later perhaps attracted by the ritual flight. But rather than mate with the female the rival bidders preferred to engage in combat with one succeeding in chasing the other off – so far in fact as to lose sight altogether of his enamarata. I would have liked to have photographed this behaviour especially when the second male joined the dance. But at 1000 of a second at F22, for depth of field, it would have required flash.

Storrs Hill supported a small colony of Common Blues with some 6 to 10 on the wing throughout the flight period. They have been reduced in number since the mid 50s as their foodplant has been much restricted in range. Nevertheless an egg laying female chose an impoverished looking plant on practically bare ground to lay its eggs. It was a typical female. The ratio of blue females to typical females appeared to be 50/50. There was a small, very tattered typical female which is the first we have seen in the north. On Ranmore Common on the North Downs small females are not infrequent. Over all the female Common Blue displays a tendency to brood varieties not only in colour and markings but also in size. The fact that this female was dished suggests it has been on the wing for some time possibly emerging even before the males. If the cause of its much reduced size is speeded-up development there must be a reason for it. Interestingly, we saw a male on Storrs Hill with a faint, brownish flush particularly on the under wing costal margin of the upper side. We were unable to get a photograph however. All the butterflies seemed to be a fraction smaller than those on the lowlands in the marshalling yards which are hardly surprising given the elevation and exposed position.

Since the mid 1950s the favourability of habitat has been completely reversed. The butterfly is flourishing in the marshalling yards. It is barely hanging on at Storrs Hill. In the mid 1950s the yard was covered in soot and grime and toxic, phosphorescent waste. I barely remember anything flourishing there it was such a foul, fetid evil-smelling place with steam trains (War Dogs) belching smoke pulling wagons of coal ballast freight passing through every few minutes. Today I was drawn away from a nest by a hen partridge. Later I flushed up two more! Photographed a Brimstone moth and Swallowtail moth on ground above Healey Mills yards. I recall on at least a couple of occasions in the 1950s being in the vicinity of the marshalling yards at night and noticing the number of moths attracted to the arc lights.

 

2nd July 2001: Otley gravel pits

Found a male Common Blue in the Otley gravel pits. Strange to say we did not find one single plant of trefoil within the immediate vicinity. Went on to the Burley -in-Wharfedale by-pass. There was easily enough trefoil to support a substantial population but there were no Common Blues to be seen anywhere. How long will it take for them to get there? This year, next year, or many years hence?

Explored Baildon Bank but apart from one sparse plant there was insufficient trefoil to support a small population of Common Blues. I was about to give up having descended the rock face towards Saltaire when I found masses of trefoil. I suddenly realised this was the place I had been looking for all along since 1996 when I first saw the common blues in Bradford apart from on Shipley station. Baildon Green is undoubtedly an old site going back many centuries. The Common Blue must have been flying there for some t considerable time. The blackened stone of the quarry face suggests it could never have been a 'clean' site and whatever vegetation was there would also have been grimy. The area is grazed with horses and goats and since it is a village green this will have been a time-honoured practise stopping the grass and shrubs eventually shading out the trefoil. The shorter birds foot trefoil was consequently growing in great abundance but in the damper, more shaded places there were many clumps of greater birds foot trefoil.

 

12th July 2001: Ben Rhydding gravel pits

Very windy and rather showery with sunny spells in between. The Ringlets appear not to have taken advantage of the path we cut through the trees last winter. Instead of grasses, nettles have grown up in profusion. So the Ringlets end exactly where they did last year and there was not one in the area we hoped they would have by now colonised. The numbers appear to be pretty much what they were last year. I may be mistaken but the number of normal forms seem to be increasing. Chatted with a fisherman who was also a naturalist. He had a digital camera and a computer. He was so eager to chat and I couldn't cut him short which also meant I was unable to take photographs. The gravel pits had been worked up until the early 1960s. He recalled a wooden house which had stood at the end of one of the flooded gravel pits. From the living room window fish could be seen jumping. It was evident the magic of the place had gripped him as if it was a better way of living.

Moved onto Burley in Wharfedale. I found the hoped for ringlet close to where the path along the Wharfe enters the wooded embankment. It was a normal form but also rather pale. By the time I reached Otley it was around 5 in the evening dull and rather chilly. Not a hope,

 

12th July 2001: Ben Rhydding gravel pits, West Yorks

Back to the gravel pits. I was more focussed than yesterday due to David's presence. Beyond doubt the percentage of ringlet variation remains very high, possibly as much as 80%. Few were in prime condition because of the high winds which have characterised the last two days. Many had nicks in their wings and I saw at least a couple of Ringlets lifted by the high winds losing flight control and becoming literally impaled on thistles. The same was true of the Meadow Brown and alone, hopeless Cinnabar. The only butterfly that seemed able to ignore the high winds was the Large Skipper probably because of its smaller wing area, both yesterday and today it was to be seen nectaring on the scabious high up on the banks of the River Wharfe where it was particularly windy.

A further investigation of the area we cleared showed there weren't any Ringlets yet. Back in the area where we first found the Ringlets we noticed they had consolidated their colonisation of the small clearing to the west. Here they would actually fly virtually into the river bank – certainly into the trees over-hanging the Wharfe. Some would even perch on the lower branches of trees. I tried to get a photo of one on a young ash tree. David later saw one select an elder tree in which to roost for the night.

We moved on to what we called "Son of Ben Rhydding" in Burley–in-Wharfedale. In spite of the sporadic sunshine we eventually found the Ringlet – three in all. So there is a colony – but of recent origin. All were normal specimens. And they still have yet to reach Ben Rhydding gravel pits. Whilst at "Son of Ben Rhydding" I noticed a goldfinch across the Wharfe and suddenly stop mid-flight. To flutter above grass stalks and spear an insect. The short quick wing bursts probably give it this manoeuvrability. How many of these flocks of birds are to be found in Ben Rhydding? certainly a fair proportion of the Ringlets had beak marks. Perhaps typical spotting provides too much of a target and actually outweighs the advantage of providing a target area away from the soft body parts.

Moved onto Otley. By now it was getting late and the sky had become overcast. Even so we kicked up a number of Ringlets in a field close by the Gallows Hill allotments. All were typical specimens – dark brown with precise eye spots.

Conclusion: the immature colony of "Son of BR" has almost certainly come from the Otley direction. And it has yet to reach Ben Rhydding gravel pits. What will happen when it does so?

Colour: reddish upper wings on a Ringlet particularly on upper costal margins. Similar in fact to the male Meadow Brown. This in Ben Rhydding gravel pits. Seemed to be dependent on angle of vision which suggests the ringlets wings partially iridise.

Large Skipper: Observed and photographed a pair of mating Large Skipper at "Son of BR". Their behaviour was similar to the Common Blue on Shipley Station Meadow once they had ceased mating. They turned to face each other as if in acknowledgement. How anthropomorphic I thought and how deceptive if one really knew the reason why.

 

14th July 2001: Gaisby/Wrose Quarries, Bradford, West Yorks

We failed to see one Common Blue female and left after a short while, disappointed and puzzled. We even came to the conclusion that on the highlands there was an unhealthy disproportionate number of males which meant the colonies were unlikely to survive. In fact we were of the opinion there were even less butterflies on the wing than ten days ago. Of the males a fair number (hardly surprising given the gale force winds of the last few days) but some were pristine having in all probability just emerged.

We then moved off to Wrose Brow at Wing Hill Quarries. Like at Gaisby Quarries there was hardly a Common Blue to be seen. But then the sun came out and everything changed. By the end of the day we realised far more blues were on the wing than ten days ago. In fact it is a considerable colony. Blue females predominate and the variation within this form appears to be greater than on Shipley Station Meadow ranging from blue under wing females with fairly typical upper wings to totally blue females indistinguishable from the males except for the border of orange lunules. Unfortunately, we were unable to obtain photos of these aberrations apart from one of the former with its wings half open. It is a magnificent, imposing site but the problem of photography are exacerbated by the terrain and the high winds. The weather forecast had predicted a light, northerly wind! Not here however, at Windhill is surely a more appropriate name. In fact the blues seemed to favour a particularly exposed ridge visible from far down below on the valley floor of Shipley station. On this rather bare hillside could be found sparse clumps of sheep fescue, knapweed and birds foot trefoil. Slabs of rock from the quarry face formed a slippery scree slope preventing the ridge from ever becoming totally grassed over. Though very exposed and high up this bank side caught the sun's rays directly and was obviously a much favoured spot by the Common Blues in spite of the gusts of wind which periodically would sweep the Common Blues up the hillsides and over the top. When caught by the winds they would be rapidly lost to view – not only to us humans but also their potential predators. The relationship between wind and the Common Blue needs to be carefully investigated and their adaptation to it must help their survival chances.

Superficially it might appear there are far more males than females on these sites – or any other site for that matter like Shipley Station Meadow. However, they could be more invisible and their behaviour after mating is very different to that of the male. Possibly they spend a far greater length of time deep in the grass and searching out areas where trefoil grows. Noticed just one typical female. However it was quite small almost a dwarf form, similar to the one brown female on Storrs Hill. If the typical females have a tendency to be small it may suggest speeded-up development time or truncated growth for some reason.

 

11th July 2001: Baildon Green, West Yorks

A disappointment. Unable to obtain any photographs. One egg laying blue female briefly opened its wings to reveal that it had white spots with a central dot on each of the four wings. I did not see one male though as the sun was only out for around half an hour. It is a warm sheltered site with patches of bare earth close to the dwarf trefoil. I have a feeling that this Common Blue population emerges fractionally earlier than that on Shipley Station Meadow. All that are now left are stragglers – chiefly egg laying females. On good years there probably is a second generation in August. I feel certain I saw them in August 1996. At least the stragglers were left to egg lay in peace without persistent pestering from the males. This was very evident later in the day when a blue female on Wrose Brow was assaulted by three males when preparing for egg laying sites.

Moved on to Gaisby Quarries. In spite of the profusion of trefoil the Common Blues were pretty thin on the ground. We did see several blue females and an unusually small male which we managed to photograph. Dwarf forms tended to occur amongst the female and is therefore sex linked. The butterflies tended to congregate on the high fringe of the quarry. There was no sign of them on the quarry floor. Possibly they have died off here and the trefoil had gone back, the claw foot seed pods being very visible. Because of the abrupt changes in altitude in the quarries, emergence times may vary quite considerably. So the quarry floor populations may emerge at roughly the same time as at Shipley station and Baildon Green.

Then on to Wrose Hill. This site contains more Common Blues than any other in Bradford. One of their favoured spots is by the side of the road (Carr Lane), the hot draughts of air from the burning tarmac suiting the butterfly perfectly. After 5 30 they are to be found sunning themselves in the quarry they more or less ceased to fly.

 

5th August 2001: Scrubs Lane, West London

The Hedge Brown now outnumbers the Meadow Brown. Why this sudden movement into strange new habitats? I saw one for instance outside the main entrance to the flats in Acklam Rd, Notting Hill right next to the Westway fly over. It must have travelled some distance. The nearest, fairly suitable area of grassland is now some half a mile away. Wanted to take a 'typical' photo, as the butterfly has begun to colonise new areas this maybe merely stereotypical e.g. lots of bramble leaves with sprays of fruit – perhaps with some oak leaves somewhere in the background.

Tried to take a photo of Speckled Woods with an avenue of horse chestnuts in the background. The main aim is to suggest a wooded area. An avenue of trees would be stereotypical but it would get across the notion of woodland. The aim is to take photos of butterflies in a variety of habitats and situations each of which conveys an accurate impression of the butterfly.

"Like its close relative, it undoubtedly lives in clearly defined colonies, with little or no migration between nearby sites. It is very rare for Gatekeepers to appear in city gardens, even in counties where the species is abundant" (Quotes are not credited)

 

9th August 2001: Elland, Calderdale, West Yorks

Found a number of Purple Hairstreaks in Elland cemetery. If I had not known they were there I could have walked through the area and confidently pronounced none were there. A few came down onto small oaks but most preferred to stay well out of range close to the top of medium sized oaks or sycamores. In fact in West Yorks they show as great a liking for sycamores as for oaks. One sycamore in particular they showed a preference for standing a little away from other taller sycamores. Contrary to expectations they did not come down to late afternoon, retreating higher up the trees to catch the sun's rays. This behaviour is different from their southern counterparts.

The Purple Hairstreaks do not flatten their wings against the leaves as do the Black Hairstreaks and especially, the Green Hairstreaks. In fact they have a tendency to walk rapidly over the leaves and up and down the stems searching perhaps for aphid honeydew or even sap. Occasionally they will stop and rest for awhile opening their wings in the sun before flitting off to alight on another leaf.

We found none along the main road from eland into Halifax though oaks were massed on the bank side. Perhaps the exhaust from passing traffic was contaminating the honey dew. But along the Calder canal we immediately saw hairstreaks counting around 10 in four minutes. The canal ran along side the roadway some twenty foot lower down. It was considerably warmer along the canal bank than at the top of the cliff face where the cemetery is situated. Disturbed a couple of Purple Hairstreaks resting or nectaring on the Himalyan balsam as the canal branched off to Sowerby Bridge. Still not clear what the relationship is with the balsam.

May have found a White Letter Hairstreak colony along the Halifax arm of the canal.

 

12th August 2001: Judy Woods, Bradford, West Yorks

Rained practically the entire day searched for potential Purple Hairstreak sites. Learnt something about the distribution of the oak. Seems to prefer the lee side of the escarpment, the oakwoods proper ending at Woodside. The oaks in Odsal Wood we reckoned had been put there by the railway company some one hundred years ago. We reasoned the company thought the spreading root system of the oak held the bank sides of the railway line together, preventing soil creep and so on. In which case the Purple Hairstreak may well be spreading along railway embankments wherever oaks have been planted, helped by the oaks in more traditional woodland.

 

13th August 2001: Brownroyd Hill and Odsal Woods, Bradford, West Yorks

The day promised to be fine but in fact it clouded over and remained overcast until around 6 o clock in the evening. However, in spite of the absence of sunshine it was a warm day. On our second walk through Brownroyd Hill we failed to turn up any Purple Hairstreaks. However, it was windy and there was hardly any sun.

We saw a Purple Hairstreak almost as soon as we arrived at Odsal Woods. It is obviously a vast colony and we must have seen around 60 in spite of the absence of sun. None however came down and all stayed in the canopy. They also tend to stay away from the prevailing winds even preferring trees that are in the shade provided they are sheltered.

Some remarks on the cryptic colouration. Oak leaves when attacked by insects (as they frequently are) can form purplish brown patches almost the colour and shape of the under side wings of the Purple Hairstreak. Newish twigs also have a purplish hue which can be scaled off. As the Purple Hairstreak likes to climb up and down outermost twigs it must provide a measure of protection. Purple Hairstreaks rarely rest for long on a leaf and the continual movement of leaves in the wind actually helps disguise their movements. A moment's lapse of attention and what you think is the hairstreak is in fact a leaf twisting and curling in the wind.

Coming back via Brownroyd Hill we espied a Purple Hairstreak around 6 40 in the evening. What a coup! As the hill is not in the direction of the prevailing winds, a wind would have to blow directly from the east to lift the purple hairstreak from Odsal Woods to Brownroyd Hill. This suggests the insect is now all over Bradford and every oak tree could contain a small colony. It has crept in unawares until now because it's profile is unmistakeable.

The colonies in Woodside and Odsal must have been there for at least ten years. Given there size I would say from 15 to 20 years but this is probably an exaggeration.

 

14th August 2001: Styal Prison Country Park, Cheshire

This disaster requires another book. Thought of Thoreau as I sat on the train coming back. His 'naturalness' is no longer possible; we are surrounded, there is no escape like the high wire of Styal prison. Like it or not we have to live with this shit, there is nothing even remotely approaching that margin of freedom possessed by Thoreau. Downcast I walked through Styal Country Park to Wilmslow. What I took initially to be Purple Hairstreaks turned out to be speckled woods flitting about in the lower branches of the oaks in more or less the full sunshine. In fact the behaviour was most unusual. During the entire walk of near on two miles I only saw one Purple Hairstreak and it was just at the right time between 4 and 6.

I may however have seen one from the train window at Levenshulme which set me thinking. Perhaps they are being pushed out of country areas by the massive use of herbicides and pesticides finding the town rather less noxious. It's a thought.....

How much have the oaks followed those giant earthworks, the canals and railways? There are grounds for thinking that steep bank sides overlooking canals had been planted with oaks to bind the soil and stop landslides from blocking the canal. Later this practise was taken up by the railway builders. There may have been ideological reasons also – 'hearts of oak' and the Victorian engineers thought they were creating something mighty and permanent.

Railways could easily have acted as corridors for the butterfly as also the canals. With the ending of steam trains trees were able to take root more easily on the bank sides as fires caused by red hot cinders became a thing of the past. Most embankments have the characteristic look of carr with birch, alder, oak, sycamore. Most of this will have grown up in the past thirty years roughly coinciding with the growth of motorway verges – trees, shrubs, plants and so on.

Do birds follow railway, lines rather than diving off into an empty countryside? Maybe we can speak of a 'straight line' dissemination of seeds.

 

25th August 2001: Bradford, West Yorks

Found the Purple Hairstreak in Bierley Hall Wood. Sae two or three in all and they appear to be falling off rapidly at least here. Moved on to Odsal Woods to give ourselves a yardstick. Here the butterfly had virtually gone. We saw two in all though it was a perfect day for them with little wind. The one we did manage to get close to was clearly dished.

Finally we made it to Wibsey Park and though the sky was now overcast we saw at least three jinking about the low oaks – and this was around 6 30 in the evening. Delayed emergence because of the elevation and exposure to westerlies may explain their presence when numbers should be rapidly declining.

 

26th August 2001: Bull Greave Wood, Clayton Quarries, Beckfoot Bradford 14, West Yorks

For awhile it seemed there were no Purple Hairstreaks, which if it were the case would mean the butterfly is still in the process of occupying Bradford. But in the westerly edge of the gully in Bull Greave Wood, I eventually found one -then a further two - on an English oak which stood slightly apart from the main body of the rift wood. We managed to get some photos of bedraggled specimens. Descending to the rift wood floor we did not see one in spite of the large number of oaks. The conditions here were perfect for the butterfly and the last stragglers must have perished several days ago. On the other side however, we found a couple on an exposed oak. Probably development times are different between the upland and lowlands even in a relatively small wood like this. Late in the season it only makes sense to look for the Purple Hairstreak on exposed, windswept oaks.

It is possible that Purple Hairstreaks in the north do not have the same hint of blue on the upper wings as they do in the south. There is little point in looking further in Bradford. They are everywhere. But it is still worthwhile making a mental note of any oak tree espied in the Bradford area. If there are a few oaks it would be surprising if the butterfly was not to be found there.

The Clayton site is interesting because of the presence of bramble and Himalayan balsam. Perhaps at the height of the season they do come down to nectar on these plants. It is curious that we have never seen them before here and the only explanation I can offer is that we weren't looking. Oaks generally are not found amongst houses in Bradford even those going back over one hundred years and they must have been felled because of the danger their root system presented to the foundation. Also one rarely comes across them in cemeteries for similar reasons. Oaks also may have been felled to provide fuel and frames for early spinning machinery. Once these had gone then beech was planted. Around Bradford one tends to find beech and oak together on hilly, wooded areas and the likelihood is both were planted way back.

 

28th August 2001: Leeds / Liverpool Canal

Walked down Leeds/Liverpool canal from Shipley to a little way beyond Apperly Bridge. As expected we found a number of Purple Hairstreak stragglers at different points along the canal. There is an art to finding them as they spend most of their time in the top canopy especially oaks. Hence they have come into Bradford all but unnoticed. It would be interesting to get some idea of the absolute size of the population – how many thousands, even hundreds of thousands. One could give a rough estimate by counting the numbers of oaks per acre and then the numbers of hairstreaks per tree. Are they present in the same numbers as in ideal spots like the North Downs i.e. Ashstead Forest? Crucially is their behaviour different especially in coming down to nectar. They may well spend nearly all their time in the canopy which explains why they have been overlooked for so long. The more one becomes aware of the insects range in Bradford the more astounding the oversight becomes.

The fact that canals and railways have been vitally important in the spread of the Purple Hairstreak into the Pennines may explain some of their behavioural idiosyncrasy. The oaks on the canals for instance come right down to the waters' edge and the woodland floor is typically barren of all flowering plants including bramble. Consequently they often have to fly across the canal before encountering any flowers. This may lead to a certain reluctance causing the hairstreaks to remain within the confines of the oak trees on the opposite side of the canal. The same or similar behaviour may not necessarily be true on railway embankments and difficulties of access here may prevent a person from observing their behaviour more precisely in these spots.

Also saw two male Common Blues at a new spot close to the Apperley Bridge viaduct near Woodhouse Grove School. David also saw a Holly Blue proving that there is a second generation in West Yorks. Apparently there was not one sighting of the first Holly Blue generation this year.

Woods in Bradford

1. Buck Wood (comes right down to the canal)

2. Poggy Wood

3. Dawson Wood (stopped by railway fencing from visiting)

4. Calverley Wood

5. West Wood (near church on Harrogate Road)

6. Around to Fagley: Bill Wood, Round Wood, Ravenscliffe Wood

 

28th August 2001:

As expected we found the Purple Hairstreak along the Leeds/Liverpool canal going from Shipley to the aqueduct to the fringes of Hirst Wood. We then walked along the Aire finding a number of hairstreaks around the perimeter of Trench Meadows. On top of Shipley Glen we saw three Purple Hairstreak which was quite remarkable given the lateness of the season and the exposed situation directly open to the prevailing north westerlies. There seems little point in looking further. We need now to establish exactly where the limit of the Purple Hairstreak range is. Like say on the oaks at Bronte Falls above Haworth.

 

29th August 2001:

Only rarely does an entomologist make a discovery such as ours today. Having glimpsed the oaks on Baildon Moor on a passing bus early yesterday evening we made haste to return this morning and the very first oak I looked at proved to have a Purple Hairstreak in the canopy. It was standing alone in a field and every other tree we spent time looking at also contained a Purple Hairstreak. Very few of the trees we looked at on this slope had any fresh green leaves as, all in all, they looked very autumnal and the leaves were beginning to yellow around the edges and yet still the Purple Hairstreak continued to fly. Each oak must contain its own small colony a fact which will have to be determined better next year.

We then walked right up to the tree line on Baildon Moor and were rewarded with several sightings of the Purple Hairstreak. This must surely be the highest colony in all England. The oaks were stunted, gnarled and twisted giving out onto open moorland and bracken. How is it possible to find this insect on the windswept terrain exposed to all the elements and the worst weather imaginable? Yet there it was. It was however a perfect day, still, sunny and warm. The pity was we didn't find it on the last few oaks at the side of Wind Hill. So it will be worthwhile looking for it here next year at the height of the emergence.

A flock of meadow pipits briefly flew into the trees and sand martins were sweeping low over the tree tops. Any Purple Hairstreak colony will, on this exposed plateau be particularly exposed to predation from these insectivorous birds. A flock of birds flew out of the exposed oak some eighty yards from the small clump of five or six oaks, thus a small colony of hairstreaks would find life very hard here lacking the protection of other trees in which to fly into for rapid cover.

We also found them in the Prince of Wales Park, Eldwick spotting two within twenty five minutes. This was between 4.30 and 5 in the afternoon. Then, walking down through the steep hillside covered in pines, beech and oaks, David espied another high in the canopy. This steeply inclined slope could well be the core of the colony exposed as it is to the sun all day. Only they are very difficult to see because it is very difficult to find a vantage point from which to view these large oaks. Finally we walked along the canal from Bingley to Shipley during which time we saw four more – one at Dowley Gap locks. This was between six and seven in the evening.

(I forgot to mention that this morning we found one Purple Hairstreak in Undercliffe Cemetery. No doubt there are more but we were anxious to press on). As a result of today's findings it is now imperative that someone establishes the limits of the Purple Hairstreak's range. There is a fair chance that it has already passed through the Pennines and may even be working its way up the Settle/Carlisle railway.

Why has it been able to conquer this new territory with such apparent ease? May not its unobserved life in the canopy of oaks be the key to its success? By remaining on the top of oaks to catch as much of the sun as possible it may have outstripped parasitic wasps and flies. Thus instead of a female producing just two fully fledged off-spring to maintain the population at its present size the success rate is infinitely greater with perhaps seven or eight reaching adulthood (the imago stage) from a batch of eggs.

There is an art to finding the Purple Hairstreak. One must be determined to see them. And that means not relaxing one's attention, not even for a moment. Determined staring is usually rewarded. Many must see it but few register the fact dismissing it as a trick of the light, a leaf, a large fly and so on. Actually the short hopping flight accompanied by a silver flash is suited to the canopy. Rustling leaves and moving branches against a backdrop of blue sky and white clouds is a perfect foil for the butterfly. A glimpse of the butterfly so often turns out to be an illusion, merely a blue chink of sky in the ever restless canopy. What goes for us must also go for the birds. Looking up at the top canopy of an oak tree is like looking at two planes, a front and a back plane moving against each other. The Purple Hairstreak is able perfectly to exploit this moving mosaic of contrary planes of blue and green.

As for photography that will have to be left for the next year. Maybe Susan Stead's problem comes from having looked at field guides. Specimen shots can actually stop you seeing properly.

Against this moving mosaic of blue sky, branches, twigs, sunlight and blue sky (again) one has to stay still. Otherwise you will not se the butterfly. I think - in fact I am convinced – I did not see the butterfly on the oak-studded ridge surrounding the caravan park on Baildon Moor because I was weary. Had I been sufficiently enthused I would have seen it. One's eyes can blur, you start to think about personal problems so you then miss the insect. Strange but true.

One must be totally focussed. If you allow your mind to wonder they may be dancing around in the leaves without you being at all aware of it. You see and you don't see. It is rather like that ad with the Pandas and Kit Kat. Except you are looking and seeing while eating the Kit Kat without ever once registering the butterfly. When looking for the butterfly rooted to the spot on a hillside and especially on a canal walk, passers-by must think you are mad. Imagine coming across a person fixedly staring into the trees. Ripe for the lunatic asylum without a doubt!

 

31st August 2001: Brockadale, near Pontefract, West Yorks

A warm slight overcast day – perfect however for photography. We quickly discovered what we were looking for – a Brown Argus! It was resting on a dead head of knapweed and a very dished specimen indeed. We moved onto the main area where the Hebridean sheep are grazed. We found there a 'northern' Brown Argus with Scottish eye spots. We stayed around on the hill side for an hour or so during which time we found a couple more Brown Argus, but it was the hedge at the bottom of the steep slope which proved to be the place to find the Brown Argus in relative abundance. However, they were still outnumbered by the Common Blue. I actually managed to photograph a blue female with a very distinctive white border on the upper side lower wings than is normally the case. But the majority of females were normal with just a hint of bluish streaks spreading out from the thorax.

I also noticed a male Common Blue with faint white spots on their under wings. This is sometimes apparent in the blue females. I had never previously observed this phenomenon on the male. The Brown Argus was generally in good nick and almost certainly will be on the wing for at least up to mid September. The Northern Brown Argus appeared to favour the upper reaches of the slope. The ratio of the Northern Brown Argus is around 1: 8.

Retracing our steps I found a Brown Argus at the perimeter of the reserve leading to Wentworth. In spite of a covering of rock rose we failed to find the butterfly on the hillside leading to the wood. However, by that time (4 to 4 30) it was becoming overcast. The nearest Northern Brown Argus colony is on the North Yorks Moors some forty miles away. We have made an important discovery and we saw maybe thirty in all which is considerable bearing in mind it is a second brood.

 

1st September 2001: Steeton & Silsden near Keighley and Skipton, West Yorks

A very inconclusive day largely because of the lateness of the season and also because the day became overcast and autumnal. However, it wasn't a complete waste of time. We stopped off at Steeton and Silsden and had all of two minutes to check out the oaks in the car park before the next train to Skipton drew in.

The sun was still shining when we arrived in Skipton. Unfortunately it took us at least an hour to locate an oak by which time it was clouding in. In fact, Skipton is on the fringes of the limestone uplands and oaks are not a natural part of the landscape. We did see them –oaks - however in the grounds of Skipton Castle and around an old 18th century unkempt graveyard on the Grassington Road just out of the town centre. We assumed these oaks had been deliberately planted otherwise oaks were generally replaced by ash in hedgerows and small woods similar in fact to the limestone oak woodlands of Grass Wood in Grassington.

Between Steeton and Silsden and Skipton the oaks give out dramatically because both the railway and Leeds/Liverpool canal crosses flat ground and there are no oaks to be seen either on the railway sides or on the canal bank so the essential corridor for the spread of the Purple Hairstreak is here disrupted – maybe fatally so. We certainly did not even catch a glimpse of the tell-tale flash in spite of spending well over an hour in the graveyard in Grassington Road.

Coming back to Keighley we found a couple of reasonable sized oaks in Victoria Park. However, there were far more in Cliffe Castle Park and obviously this is the place to look for Purple Hairstreaks. We then boarded a bus to Ilkley passing through Silsden where it was apparent there were many oaks. However, On the top between Silsden in Airedale to Addingham in Wharfedale, oaks all but disappeared. Once the slopes to the valley bottom coming into Addingham oaks reappeared once more in relative abundance. It would be surprising if these oaks did not contain colony of Purple Hairstreaks. However, this will have to wait for next year.

The practising of planting oaks along canals and then railways would have been influenced by the shipping interest, as well as useful for binding the soil together after cutting embankments. With the railways it must also have been strengthened by Nelson's victory at Trafalgar in 1815 and "Hearts of Oak" was always more about the navy than 'men'. Once it proved possible to make ships from wrought iron – around 1875 – the need to plant for future oak use became a thing of the past and they then became ornamental.

A few oaks planted along railway embankments or canal cuttings would have been spread by jays, squirrels etc. An oak on the fringe of a wood at Woodside is a particularly revealing example. On the open grassland of the hillsides young oaks have been planted some seventy feet to either side and immediately in front of the oak. It is unlikely the acorns would have been carried this far by the wind. The only other explanation is that squirrels have stored the acorns on the bankside forgetting thence to dig up a number of their winter food supply allowing oaks to sprout from the leftover acorns.

This is a one explanation as to why oaks spread far up the side of steep canal cuttings and along railway embankments. This method of dispersal assisted greatly by the squirrel has also been of great benefit to the Purple Hairstreak.

 

2nd September 2001

Returned to Woodside on a cool autumnal day with little sunshine. However, amazingly, we did see Purple Hairstreaks. The first was on the lower branches and fluttering fitfully it descended on to grass in the field fringing the woodland. Once there it no longer had the strength to fly up once more. When disturbed it descended even lower into the cold rain and drenched grass with a falling movement reminiscent of the Green Hairstreak trying to escape detection. It would then after awhile begin to climb up the grass stalk in search of whatever heat and warmth there was from the sun. Significantly this distinctive walking motion typical of the Purple Hairstreak was now in one direction only – towards the light and warmth.

We were witnessing the death throws of a Purple Hairstreak. Once it opened its wing it was immediately obvious it was a very dished specimen. This field was surely the death bed and graveyard of the majority in this particular fringe of woodland. In the Pennines, Icarus-like the Purple Hairstreak spends its life in the top canopy of oak tree only eventually falling to earth, unable ever to rise again. It could be this is the only chance we ever really get to see them close to the Pennines. However, this aspect of their behaviour needs to be far more closely studied. In a hollow deep in the woodland I noticed another Purple Hairstreak wearily flapping its wings as it vainly sought to rise once more into the oaks. It disappeared down the bank side of a stream where it became lost to view. For all I know it may have perished in the water. But later on while scanning a cluster of oaks we saw a very agile Purple Hairstreak close to the top canopy. It even had the strength to fly into the brisk wind. Obviously a few are far from on their last legs.

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